December 10, 1999 / Vol. 48 / No. RR-13
Recommendations
and
Reports
U.S. DEPARTMENT OF HEALTH & HUMAN SERVICES
Centers for Disease Control and Prevention (CDC)
Atlanta, Georgia 30333
CDC Guidelines for National Human
Immunodeficiency Virus Case
Surveillance, Including Monitoring
for Human Immunodeficiency Virus
Infection and Acquired
Immunodeficiency Syndrome
Copies can be purchased from Superintendent of Documents, U.S. Government
Printing Office, Washington, DC 20402-9325. Telephone: (202) 512-1800.
Use of trade names and commercial sources is for identification only and does not
imply endorsement by the U.S. Department of Health and Human Services.
The
MMWR
series of publications is published by the Epidemiology Program Office,
Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Hu-
man Services, Atlanta, GA 30333.
Centers for Disease Control and Prevention....................Jeffrey P. Koplan, M.D., M.P.H.
Director
The material in this report was prepared for publication by
National Center for HIV, STD, and TB Prevention......... Helene D. Gayle, M.D., M.P.H.
Director
Division of HIV/AIDS Prevention—
Surveillance and Epidemiology ........................................ Kevin M. De Cock, M.D.
Director
The production of this report as an
MMWR
serial publication was coordinated in
Epidemiology Program Office............................................Barbara R. Holloway, M.P.H.
Acting Director
Office of Scientific and Health Communications ......................John W. Ward, M.D.
Director
Editor
, MMWR
Series
Recommendations and Reports
................................... Suzanne M. Hewitt, M.P.A.
Managing Editor
Darlene D. Rumph-Person
Project Editor
Morie M. Higgins
Peter M. Jenkins
Visual Information Specialists
SUGGESTED CITATION
Centers for Disease Control and Prevention. Guidelines for national human immu-
nodeficiency virus case surveillance, including monitoring for human immuno-
deficiency virus infection and acquired immunodeficiency syndrome. MMWR
1999;48(No. RR-13):[inclusive page numbers].
Contents
Introduction...........................................................................................................1
Background ...........................................................................................................2
History of AIDS and HIV Case Surveillance.................................................2
Considerations in Implementing Nationwide
HIV Case Surveillance.....................................................................................7
Guidelines for Surveillance of HIV Infection and AIDS ...................................11
HIV Surveillance Case Definition for Adults and Children ......................11
HIV/AIDS Case Surveillance Practices and Standards ............................11
Commentary .......................................................................................................17
Surveillance Case Definition for HIV Infection and AIDS ........................17
HIV/AIDS Surveillance Practices .................................................................19
Conclusion...........................................................................................................22
References...........................................................................................................22
Appendix .............................................................................................................29
References to sites of non-CDC organizations on the Internet are provided as a
service to
MMWR
readers and do not constitute or imply endorsement of these
organizations or their programs by CDC or the U.S. Department of Health and
Human Services. CDC is not responsible for the content of pages found at these
sites.
Single copies of this document are available from the CDC National Prevention
Information Network (NPIN) (Operators of the National AIDS Clearinghouse),
P.O. Box 6003, Rockville, MD 20850. Telephone: (800) 458-5231.
Vol. 48 / No. RR-13 MMWR i
The following CDC staff members prepared this report:
Patricia L. Fleming, Ph.D., M.S.
John W. Ward, M.D.
Robert S. Janssen, M.D.
Kevin M. De Cock, M.D.
Division of HIV/AIDS Prevention–
Surveillance and Epidemiology
National Center for HIV, STD, and TB Prevention
Ronald O. Valdiserri, M.D., M.P.H.
Helene D. Gayle, M.D., M.P.H.
Office of the Director
National Center for HIV, STD, and TB Prevention
in collaboration with
Jeffrey L. Jones, M.D., M.P.H.
J. Stan Lehman, M.P.H
Mary Lou Lindegren, M.D.
Allyn K. Nakashima, M.D.
Joseph M. Posid, M.P.H.
Patrick S. Sullivan, D.V.M., Ph.D.
Patricia A. Sweeney, M.P.H.
Pascale M. Wortley, M.D., M.P.H.
Division of HIV/AIDS Prevention
National Center for HIV, STD, and TB Prevention
Eva M. Seiler, M.P.A
Office of the Director
National Center for HIV, STD, and TB Prevention
Harold W. Jaffe, M.D.
Division of AIDS, STD, and TB Laboratory Research
National Center for Infectious Diseases
ii MMWR December 10, 1999
Guidelines for National Human Immunodeficiency
Virus Case Surveillance, Including Monitoring
for Human Immunodeficiency Virus Infection
and Acquired Immunodeficiency Syndrome
Summary
CDC recommends that all states and territories conduct case surveillance for
human immunodeficiency virus (HIV) infection as an extension of current
acquired immunodeficiency syndrome (AIDS) surveillance activities. The expan-
sion of national surveillance to include both HIV infection and AIDS cases is a
necessary response to the impact of advances in antiretroviral therapy, the
implementation of new HIV treatment guidelines, and the increased need for
epidemiologic data regarding persons at all stages of HIV disease. Expanded
surveillance will provide additional data about HIV-infected populations to
enhance local, state, and federal efforts to prevent HIV transmission, improve
allocation of resources for treatment services, and assist in evaluating the
impact of public health interventions. CDC will provide technical assistance to all
state and territorial health departments to continue or establish HIV and AIDS
case surveillance systems and to evaluate the performance of their surveillance
programs. This report includes a revised case definition for HIV infection in
adults and children, recommended program practices, and performance and
security standards for conducting HIV/AIDS surveillance by local, state, and
territorial health departments. The revised surveillance case definition and asso-
ciated recommendations become effective January 1, 2000.
INTRODUCTION
AIDS surveillance has been the cornerstone of national efforts to monitor the
spread of HIV infection in the United States and to target HIV-prevention programs
and health-care services. Although AIDS is the end-stage of the natural history of HIV
infection, in the past, monitoring AIDS-defining conditions provided population-based
data that reflected changes in the incidence of HIV infection. However, recent
advances in HIV treatment have slowed the progression of HIV disease for infected
persons on treatment and contributed to a decline in AIDS incidence. These advances
in treatment have diminished the ability of AIDS surveillance data to represent trends
in the incidence of HIV infection or the impact of the epidemic on the health-care
system. As a consequence, the capacity of local, state, and federal public health agen-
cies to monitor the HIV epidemic has been compromised (
1–3
).
In response to these changes and following consultations with multiple and diverse
constituencies (including representatives of public health, government, and commu-
nity organizations), CDC and the Council of State and Territorial Epidemiologists
(CSTE) have recommended that all states and territories include surveillance for HIV
infection as an extension of their AIDS surveillance activities (
1,4
). In this manner, the
HIV/AIDS epidemic can be tracked more accurately and appropriate information about
Vol. 48 / No. RR-13 MMWR 1
HIV infection and AIDS can be made available to policymakers. CDC continues to sup-
port a diverse set of epidemiologic methods to characterize persons affected by the
epidemic in the United States (
5–10
). Although HIV/AIDS case surveillance represents
only one component among multiple necessary surveillance strategies, this report
focuses primarily on CDC’s recommendation to implement HIV case reporting nation-
wide.
This report provides a revised case definition for HIV infection in adults and chil-
dren, recommended program practices, and performance and security standards for
conducting HIV/AIDS surveillance by local, state, and territorial health departments.
The case definition for HIV infection was revised in consultation with CSTE and
includes the current AIDS surveillance criteria as a component (
11
). The recom-
mended program practices and performance and security standards are based on
a) the established practices of AIDS and other public health surveillance systems;
b) reviews of state and local surveillance programs, confidentiality statutes, and secu-
rity procedures; c) studies of the performance of surveillance systems; d) ongoing
evaluations of determinants of test-seeking or test-avoidance in relation to state poli-
cies and practices on HIV testing and reporting; and e) discussions at a consultation
held by CDC and CSTE in May 1997. A draft of this report was made available for
public comment from December 10, 1998, to January 11, 1999, through a notice pub-
lished in the
Federal Register
(
12
).
BACKGROUND
History of AIDS and HIV Case Surveillance
Since the epidemic was first identified in the United States in 1981, population-
based AIDS surveillance (i.e., reporting of AIDS cases and their characteristics to
public health authorities for epidemiologic analysis) has been used to track the pro-
gression of the HIV epidemic from the initial case reports of opportunistic illnesses
caused by a then unknown agent in a few large cities to the reporting of 711,344 AIDS
cases nationwide through June 30, 1999 (
5,13–15
). The AIDS reporting criteria have
been periodically revised to incorporate new understanding of HIV disease and
changes in medical practice (
16–19
). In the absence of effective therapy for HIV infec-
tion, AIDS surveillance data have reliably detected changing patterns of HIV
transmission and reflected the effect of HIV-prevention programs on the incidence of
HIV infection and related illnesses in specific populations (
20–25
). Because of these
attributes, AIDS surveillance data have been used as a basis for allocating many fed-
eral resources for HIV treatment and care services and as the epidemiologic basis for
planning local HIV-prevention services.
With the advent of more effective therapy that slows the progression of HIV dis-
ease, AIDS surveillance data no longer reliably reflect trends in HIV transmission and
do not accurately represent the need for prevention and care services (
26,27
). In 1996,
national AIDS incidence and AIDS deaths declined for the first time during the HIV
epidemic (Figure 1). These declines have been primarily attributed to the early use of
combination antiretroviral therapy, which delays the progression to AIDS and death
for persons with HIV infection (
1–3,9
). Revised HIV treatment guidelines recommend
2 MMWR December 10, 1999
antiretroviral therapy for many HIV-infected persons in whom AIDS-defining condi-
tions have not yet developed (
28–30
). In addition, antiretroviral treatment of pregnant
women and their newborns has reduced perinatal HIV transmission and resulted in
dramatic declines in the incidence of perinatally acquired AIDS (
31,32
) (Figure 2). In
response to these changes in HIV treatment practices and the information needs of
public health and other policymakers, CDC and CSTE have recommended that all
states and territories extend their AIDS case surveillance activities to include HIV case
surveillance and the reporting of HIV-exposed infants (
1,4,33
).
Since 1985, many states have implemented HIV case reporting as part of their com-
prehensive HIV/AIDS surveillance programs. As of November 1, 1999, a total of
34 states and the Virgin Islands (VI) had implemented HIV case surveillance using the
same confidential system for name-based case reporting for both HIV infection and
AIDS; two of these states conduct pediatric surveillance only (
5
) (Figure 3). Areas that
conduct integrated HIV/AIDS surveillance for adults, adolescents, and children have
reported 42% of cumulative U.S. AIDS cases. In addition, four states (Illinois, Maine,
Maryland, and Massachusetts) and Puerto Rico, representing 11% of cumulative AIDS
cases, are reporting cases of HIV infection using a coded identifier rather than patient
name. Washington has implemented HIV reporting by patient name to enable public
health follow-up; after services and referrals are offered, names are converted into
codes. In most other states, HIV case reporting is under consideration or laws, rules,
or regulations enabling HIV surveillance are expected to be implemented during 2000.
0
5,000
10,000
15,000
20,000
25,000
Number of Cases/Deaths
Quarter-Year of Diagnosis/Death
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
1993 AIDS Case
Definition Implementation
Deaths
AIDS Cases
Number of Cases/Deaths
*Persons aged ≥13 years.
†
Adjusted for reporting delays. Data reported through June 1999.
FIGURE 1. Estimated incidence of acquired immunodeficiency syndrome (AIDS), by
quarter-year of diagnosis, and number of deaths, by quarter-year of death, among
adults* with AIDS
†
— United States, 1985–1998
Vol. 48 / No. RR-13 MMWR 3
300
0
50
100
150
200
250
Quarter-Year of Diagnosis
Number of Cases
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
Number of Cases
*Adjusted for reporting delays and unreported mode of HIV exposure. Data reported through
June 1999.
FIGURE 2. Estimated incidence of acquired immunodeficiency syndrome among
children aged <13 years who were infected with human immunodeficiency virus
(HIV) perinatally,* by quarter-year of diagnosis — United States, 1985–1998
HIV Reporting Required
Pediatric Reporting
Required Only
FIGURE 3. States with name-based human immunodeficiency virus (HIV) case
surveillance — United States, November 1999
4 MMWR December 10, 1999
In contrast to AIDS case surveillance, HIV case surveillance provides data to better
characterize populations in which HIV infection has been newly diagnosed, including
persons with evidence of recent HIV infection such as adolescents and young adults
(13–24-year-olds) (
34,35
). Of the 52,690 HIV infections diagnosed from January 1994
through June 1997 in 25 states that conducted name-based HIV surveillance through-
out this period, 14% of cases occurred in persons aged 13–24 years. In comparison, of
the 20,215 persons in whom AIDS was diagnosed in these 25 states, only 3% of cases
occurred in persons aged 13–24 years. Thus, AIDS case surveillance alone does not
accurately reflect the extent of the HIV epidemic among adolescents and young
adults. Compared with persons reported with AIDS, those reported with HIV infection
in these 25 states were more likely to be women and from racial/ethnic minorities (
36
)
(Table 1). These patterns reflect the characteristics of populations that were affected
by the epidemic more recently, but they might also reflect changes in testing practices
or behaviors (
6,36,37
). Compared with the diagnosis of AIDS, which can be delayed
among HIV-infected persons receiving antiretroviral therapy, the first diagnosis of HIV
infection is not delayed by treatment but is affected by testing behaviors and targeted
testing programs. In addition, in these 25 states as of June 30, 1999, the total number
of persons (159,083) who were reported as living with either a diagnosis of HIV infec-
tion (90,699) or AIDS (68,384) was 133% greater than that represented by the number
living with AIDS alone (
5
). Therefore, these states have documented that the com-
bined prevalence of those living with a diagnosis of HIV infection and those living with
AIDS provides a more realistic and useful estimate of the resources needed for patient
care and services than does AIDS prevalence alone.
States with confidential name-based HIV case surveillance systems have used data
on all perinatally exposed children to document the sharp decline in perinatally
acquired HIV infection, the increase in the proportion of infected pregnant women
who have been tested for HIV infection before delivery, and the high proportion of
HIV-infected pregnant women who accept zidovudine therapy (
31,38–44
). These find-
ings contribute to HIV-prevention policy development. CSTE and the American
Academy of Pediatrics have recommended that all states and territories conduct pedi-
atric HIV surveillance that includes all perinatally exposed infants to facilitate
follow-up to assess infection status and access to care (
11,31,33,40,45
).
Persons can choose to be tested for HIV in the following ways: a) anonymously—
whereby identifying information, including patient name and other locating
information, are not linked to the HIV test result (e.g., at anonymous testing sites) and
b) confidentially — whereby the HIV test result is linked to identifying information
such as patient and provider names (e.g., at medical clinics). In states that require HIV
case reporting, providers in confidential medical or testing sites are required to report
HIV-infected persons to public health authorities. Not all persons infected with HIV are
tested, and of those who are, testing occurs at different stages of their infection.
Therefore, HIV surveillance data provide a minimum estimate of the number of
infected persons and are most representative of persons who have had HIV infection
diagnosed in medical clinics and other confidential diagnostic settings. The data rep-
resent the characteristics of persons who recognize their risk and seek confidential
testing, who are offered HIV testing (e.g., pregnant women and clients at sexually
transmitted disease [STD] clinics), who are required to be tested (e.g., blood donors
and military recruits), and who are tested because they present with symptoms of
Vol. 48 / No. RR-13 MMWR 5
HIV-related illnesses. CDC estimated that, in 1996, approximately two thirds of all
infected persons in the United States had HIV infection diagnosed in such settings
(
46
). HIV surveillance data might not represent untested persons or those who seek
testing at anonymous test sites or with home collection kits; such persons are not
reported to confidential HIV/AIDS surveillance systems. However, the availability of
anonymous testing is important in promoting knowledge of HIV status among at-risk
TABLE 1. Characteristics of persons aged ≥13 years with HIV, by disease status at initial
diagnosis* — 25 states
†
, January 1994–June 1997
Characteristic
Disease status at initial HIV diagnosis
HIV AIDS
Total
No.
§
(%
)No.
§
(%
)
Sex
Male 37,996 (72) 16,866 (83) 54,862
Female 14,689 (28) 3,348 (17) 18,037
Race/Ethnicity**
White, non-Hispanic 17,929 (34) 9,171 (45) 27,100
Black, non-Hispanic 30,229 (57) 9,127 (45) 39,356
Hispanic 3,581 ( 7) 1,660 ( 8) 5,241
API/NA/Unknown 949 ( 2) 256 ( 1) 1,205
Risk/Exposure category
Men having sex with men 17,098 (32) 8,866 (44) 25,964
Injecting-drug user 9,671 (18) 3,959 (20) 13,630
Men having sex with men/
Injecting-drug user 2,088 ( 4) 843 ( 4) 2,931
Heterosexual contact 9,279 (18) 2,428 (12) 11,707
Other/Unreported 14,552 (28) 4,116 (20) 18,668
Age group (yrs)
13–24 7,200 (14) 653 ( 3) 7,853
25–29 9,384 (18) 2,239 (11) 11,623
30–34 11,916 (23) 4,503 (22) 16,419
35–39 10,030 (19) 4,608 (23) 14,638
≥40 14,159 (27) 8,210 (41) 22,369
Total
††
52,690 20,215 72,905
*For persons who had not had an HIV diagnosis before being diagnosed with AIDS, their
AIDS diagnosis date is considered their earliest HIV diagnosis date; for persons initially
reported with HIV who subsequently had AIDS diagnosed and reported, they are presented
by the earliest diagnosis date, which is their HIV diagnosis.
†
Alabama, Arizona, Arkansas, Colorado, Idaho, Indiana, Louisiana, Michigan, Minnesota,
Mississippi, Missouri, Nevada, New Jersey, North Carolina, North Dakota, Ohio, Oklahoma,
South Carolina, South Dakota, Tennessee, Utah, Virginia, West Virginia, Wisconsin, and
Wyoming.
§
Numbers are estimates after adjustments for reporting delays. Point estimates are presented
for reproducibility of the data.
Percentages may not total 100 because of rounding.
**Persons of races other than black and white were categorized as API (Asian/Pacific Islander),
NA (Native American), unknown, because estimates were too small for separate analysis.
††
Column totals include missing/other for some categories (e.g., missing sex). Persons
infected through receipt of blood or blood products are included under other/unreported
risk.
6 MMWR December 10, 1999
populations and provides an opportunity for counseling to reduce high-risk behaviors
and voluntary referrals to appropriate medical diagnosis and prevention services.
Despite their current limitations, HIV and AIDS case surveillance data together can
provide a clearer picture of the HIV epidemic than AIDS case surveillance data alone.
Therefore, CDC and CSTE continue to recommend that all areas implement HIV case
reporting as part of a comprehensive strategy to monitor HIV infection and HIV dis-
ease. The strategy should also include surveys of the incidence and prevalence of HIV
infection; AIDS case surveillance; monitoring HIV-related mortality; supplemental
research and evaluation studies, including behavioral surveillance; and statistical esti-
mation of the incidence and prevalence of infection and disease.
Considerations in Implementing Nationwide
HIV Case Surveillance
The nationwide implementation of the 1993 expanded AIDS surveillance case defi-
nition prompted renewed discussions of the rationale and need for data representing
HIV-infected persons who did not meet the AIDS-defining criteria. Because many
states were considering implementing HIV reporting, CDC held a consultation in 1993
with public health and community representatives to discuss relevant issues and
concerns. Community representatives’ main concerns were that the security and con-
fidentiality standards of surveillance programs might not be sufficient to prevent
disclosures of information and that many persons at risk for HIV infection might there-
fore delay seeking HIV counseling and testing because of these confidentiality
concerns. The consensus of the consultants was that few published studies were of
sufficient scientific quality to assess these concerns. Therefore, the consultants identi-
fied several areas that required additional research and policy development before
CDC and CSTE should consider recommending further expansion of HIV surveillance
efforts. These areas included a) the impact of reporting policies on testing behaviors
and practices, including the decreased availability of anonymous testing in some
states; b) the role of surveillance data in linking reported persons to prevention and
care programs; c) the development of recommended standards for the security and
confidentiality of publicly held HIV/AIDS surveillance data; and d) determining
whether alternatives to reporting of patient names would reduce confidentiality risks
while meeting the needs for high-quality surveillance data.
In response to the consultants’ recommendations, CDC initiated several research
projects to a) assess the effect of confidential name-based HIV surveillance on per-
sons’ willingness to seek HIV testing and care; b) review program practices and legal
requirements for the security and confidentiality of state and local HIV/AIDS surveil-
lance data; and c) evaluate the performance of coded-identifier–based surveillance
systems. Findings from these projects and expert advice from participants at numer-
ous technical meetings and consultations held during the intervening period have
guided formulation of the policies and practices recommended in this report. The find-
ings from these projects are summarized in the following three subsections: HIV
surveillance and testing behavior, HIV surveillance using non-name-based unique
identifiers, and confidentiality of HIV surveillance data.
Vol. 48 / No. RR-13 MMWR 7
HIV Surveillance and Testing Behavior
Few studies have characterized test- or care-seeking behaviors in relation to state
HIV reporting policies. A 1988 general population study of previous or planned use of
HIV testing services did not identify an association of reporting policy with testing
behavior (
47
). In contrast, interviews of persons seeking anonymous testing in 1989
documented that many would avoid testing if a positive test resulted in name report-
ing or partner notification (
48
). A review of the published literature on HIV testing
behaviors highlighted several limitations and biases in previous studies (
49
), includ-
ing small numbers, lack of geographic and risk-group representativeness, and
analysis of intent to test rather than of actual testing behavior. An additional limitation
of the available literature is that studies published 5–10 years ago might not reflect
actual testing behaviors in the current treatment era. Literature that highlights poten-
tial misuse of public health surveillance data might have the unintended effect of
increasing test avoidance among some at-risk persons (
50
). Examining knowledge of
and perceptions about testing and reporting, as well as actual testing behavior, in the
context of current treatment advances and evolving HIV reporting policies, can
address some of the limitations of previous research.
To determine the effect of changes in reporting policies on actual testing behaviors
among persons seeking testing at publicly funded HIV counseling and testing sites,
CDC and six state health departments reviewed data routinely collected from these
sites to compare HIV testing patterns during the 12 months before and the 12 months
after implementation of HIV case surveillance (
51
). In these areas, the number of HIV
tests increased in four states and decreased in two states; the declines were not statis-
tically significant. All the analysis periods (25-month periods during 1992–1996)
antedated the widespread beneficial effects of highly active antiretroviral therapy.
Slight variability in testing trends was observed among racial/ethnic subgroups and
HIV-risk exposure categories; however, these data do not suggest that, in these states,
the policy of implementing HIV case reporting adversely affected test-seeking behav-
iors overall (
52
).
CDC also supported studies by researchers at the University of California at San
Francisco and participating state health departments to identify the most important
determinants of test seeking or test avoidance among high-risk populations and to
assess the impact of changes in HIV testing and HIV reporting policies. Data from
these surveys of high-risk persons in nine selected states about their perceptions and
knowledge of HIV testing and HIV reporting practices documented that few respon-
dents had knowledge of the HIV reporting policies in their respective states (
53,54
). In
surveys conducted during 1995–1996, respondents reported high levels of testing,
with approximately three fourths reporting that they had had an HIV test. The most
commonly reported factors (by nearly half of respondents) that might have contrib-
uted to delays in seeking testing or not getting tested were fear of having HIV infection
diagnosed or belief that they were not likely to be HIV infected. “Reporting to the gov-
ernment” was a concern that might have contributed to a delay in seeking HIV testing
for 11% of heterosexuals, 18% of injecting-drug users, and 22% of men who have sex
with men; <1%, 3%, and 2% of respondents in these risk groups, respectively,
indicated that this was their main concern. Concern about name-based reporting of
HIV infections to the government was a factor for not testing for HIV for 13% of hetero-
sexuals, 18% of injecting-drug users, and 28% of men who have sex with men. As
8 MMWR December 10, 1999
the main factor for not testing for HIV, concern about name-based reporting to the
government was substantially lower in all risk groups (1% of heterosexuals, 1% of
injecting-drug users, and 4% of men who have sex with men) (
55
). These findings
suggest that name-based reporting policies might deter a small proportion of persons
with high-risk sex or drug-using behaviors from seeking testing and, therefore, sup-
port the need for strict adherence to confidentiality safeguards of public health testing
and surveillance data. In addition, the survey documented that the availability of an
anonymous testing option is consistently associated with higher rates of intention to
test in the future. In this survey, high levels of testing, together with high levels of test
delay or avoidance associated with reasons other than concern about name reporting,
suggest that addressing these other concerns may have a greater effect on testing
behavior. For example, 59% of men who have sex with men reported being “afraid to
find out” as a factor for not testing, and 27% reported it as the main factor for not
testing. In addition, 52% of men who have sex with men reported “unlikely to have
been exposed” as a factor for not testing, and 17% reported it as the main factor.
In a companion survey of persons reported with AIDS in eight of these same states,
participants who had recognized their HIV risk and sought testing at anonymous test-
ing sites reported entering care at an earlier stage of HIV disease than persons who
were first tested in a confidential testing setting (e.g., STD clinics, medical clinics, or
hospitals), where persons are frequently first tested when they become ill (
56
). These
data suggest that anonymous testing options are important in promoting timely
knowledge of HIV status for some at-risk persons.
HIV Surveillance Using Non-Name-Based Unique Identifiers
To assess the feasibility of using alternatives to confidential name-based methods
for HIV surveillance, several states implemented reporting of cases of HIV infection or
CD4 (a marker of immunosuppression in HIV-infected persons) laboratory test results
using various numeric or alphanumeric codes. Other states considered or tried to con-
duct case surveillance without name identifiers by using codes designed for
nonsurveillance purposes (e.g., codes intended for use in tracking patients in case-
management systems) (
57
). In May 1995, CDC convened a meeting at which these
states identified operational, technical, and scientific challenges in conducting surveil-
lance using coded identifiers rather than patient names. The states recommended that
CDC evaluate additional coded identifiers and assist them in documenting and dis-
seminating the results of their findings.
In addition, CDC supported research to evaluate the performance of a coded unique
identifier (UI) in two states that implemented a non-name-based HIV case-reporting
system while maintaining name-based surveillance methods for AIDS (
58
). The study,
conducted by Maryland and Texas during 1994–1996 in collaboration with CDC, docu-
mented nearly 50% incomplete reporting, in part because the social security number
necessary to construct the identifier code was not uniformly available in medical or
laboratory records. In Maryland, provider-maintained logs were needed to link the UI
to name-based medical records to obtain follow-up data (e.g., on HIV risk/exposure).
A more recent evaluation conducted by the Maryland Department of Health and Men-
tal Hygiene (MDHMH) reported data from a publicly funded counseling and testing
site and documented a higher level of completeness of HIV reporting (88%) than the
50% documented in the previous study (
58,59
). MDHMH reports that their code is
Vol. 48 / No. RR-13 MMWR 9
unique to a given person and that assignment of two different codes to the same per-
son is unlikely. That is, the probability that a given code can distinguish one person
from any other is >99% if all the elements of the code are complete and accurate. No
published evaluations have assessed the probability of assigning the same code to
different persons, which could occur if elements of the code were missing. In contrast
to MDHMH’s findings, analogous evaluations in Texas, as well as studies that used
more diverse methods in Los Angeles and New Jersey, failed to identify a code that
performs as well as name-based methods (
58,60–67
). On the basis of published
evaluations (
58
), Texas recently switched to name-based HIV case surveillance.
In addition to Maryland, three other states (Illinois, Maine, and Massachusetts) and
Puerto Rico recently implemented HIV reporting using four different coded identifiers.
CDC will assist these states in implementing their systems, establishing standardized
criteria for assessing the overall performance of their systems, as well as assessing
whether the required standards are achieved. Additional evaluations will be con-
ducted by the respective state health departments, in collaboration with CDC, to
determine a) the ability of coded identifiers to accurately track disease progression
from HIV infection to AIDS to death, b) their utility for evaluating public health efforts
to eliminate perinatal HIV transmission, c) their acceptability, and d) their usefulness
in matching to other databases (e.g., tuberculosis).
Confidentiality of HIV Surveillance Data
A 1994 review of state confidentiality laws that protect HIV surveillance data docu-
mented that all states and many localities have legal safeguards for confidentiality of
government-held health data (
68
). These laws provide greater protection than laws
protecting the confidentiality of information in health records held by private health-
care providers. Most states have specific statutory protections for public health data
related to HIV infection and other STDs. However, state legal protections vary, and
CDC supports additional efforts to strengthen privacy protections for public health
data. On the basis of input from expert legal and public health consultants, the
Model
State Public Health Privacy Act
(
69
) was developed by an independent contractor at
the behest of CSTE. If enacted by states, the provisions of the Model Act would ensure
the confidentiality of surveillance data, strengthen statutory protections against dis-
closure, and preclude the intended or unintended use of surveillance data for
non-public health purposes.
CDC has reviewed state and local security policies and procedures for HIV/AIDS
surveillance data. Since 1981, states have conducted AIDS surveillance, and few
breaches of security have resulted in the unauthorized release of data (
70,71
).
Because survival has improved for HIV-infected persons, information about them
might be maintained in public health surveillance databases for longer periods. This
has resulted in increased concerns about confidentiality of surveillance data among
public health and community groups (
72
). Therefore, CDC has issued technical guid-
ance for security procedures that include enhanced confidentiality and security
safeguards as evaluation criteria for federal funding of state HIV/AIDS surveillance
activities (
73
). The receipt of federal surveillance funding depends on the recipient’s
ability to ensure the physical security and confidentiality of case reports. At the federal
level, HIV/AIDS surveillance data are protected by several federal statutes, which
ensure that CDC will not release HIV/AIDS surveillance data for non-public health
10 MMWR December 10, 1999
purposes (e.g., for use in criminal, civil, or administrative proceedings). Privacy is also
ensured by the removal of names and the encryption of data transmitted to CDC. On
the basis of the importance of maintaining the confidentiality of persons in whom HIV
infection has been diagnosed by public or private health-care providers, CDC has
recommended additional standards to enhance the security and confidentiality of HIV
and AIDS surveillance data (
74,75
).
GUIDELINES FOR SURVEILLANCE
OF HIV INFECTION AND AIDS
HIV Surveillance Case Definition for Adults and Children
CDC, in collaboration with CSTE, has established a new case definition for HIV
infection in adults and children that includes revised surveillance criteria for HIV infec-
tion and incorporates the surveillance criteria for AIDS (
17–19,76
) (Appendix). HIV
infection and AIDS case reports forwarded to CDC should be based on this definition.
For adults and children aged ≥18 months, the HIV surveillance case definition includes
laboratory and clinical evidence specifically indicative of HIV infection and severe HIV
disease (AIDS). For children aged <18 months (except for those who acquired HIV
infection other than by perinatal transmission), the HIV surveillance case definition
updates the definition in the 1994 revised classification system. In addition, the new
case definition is based on recent data regarding the sensitivity and specificity of HIV
diagnostic tests in infants and clinical guidelines for
Pneumocystis carinii
pneumonia
(PCP) prophylaxis for children
(19,77–88
) and for use of antiretroviral agents for pedi-
atric HIV infection (
30
). The revised surveillance case definitions for adults and
children become effective January 1, 2000.
HIV/AIDS Case Surveillance Practices and Standards
CDC and CSTE recommend that all states require reporting to public health surveil-
lance of all cases of perinatal HIV exposure in infants, the earliest diagnosis of HIV
infection (exclusive of anonymous tests) and the earliest diagnosis of AIDS in persons
of all ages, and deaths among these persons (
4,33
). Such reporting should constitute
the core minimum performance standard for HIV/AIDS surveillance in all states and
territories. CDC provides federal funds and technical assistance to states to establish
and conduct active HIV/AIDS surveillance programs. On the basis of feasibility, needs,
and resources, areas may be funded to implement additional surveillance activities
(e.g., supplemental research and evaluation studies and serologic surveys), but these
approaches might not be necessary in all areas. The following recommended prac-
tices update and revise the
CDC Guidelines for HIV/AIDS Surveillance
released in 1996
and updated in 1998 as a technical guide for state and local HIV/AIDS surveillance
programs (
34,73–75
). Recommended practices represent CDC’s guidance for best
public health practice based on available scientific data. Programmatic standards set
minimum requirements for states to receive support from CDC for HIV/AIDS surveil-
lance activities.
Vol. 48 / No. RR-13 MMWR 11
Recommended Surveillance Practices
• All state and local programs should collect a standard set of surveillance data for
all cases that meet the reporting criteria for HIV infection and AIDS. The standard
data set includes the a) patient identifier, b) earliest date of diagnosis of HIV infec-
tion, c) earliest date of diagnosis of an AIDS-defining condition, d) demographic
information (e.g., date of birth, race/ethnicity, and sex) and residence (i.e., city
and state) at diagnosis of HIV infection and of AIDS, e) HIV risk exposure, f) facil-
ity of diagnosis, and g) date of death and state of residence at death. In addition
to this information, the date of HIV diagnostic testing, the results of these tests,
and exposure to antiretroviral treatment for reducing perinatal HIV transmission
should be collected for all infants with perinatal exposures to HIV. Surveillance
information, without patient identifiers, should be encrypted and forwarded to
CDC through the HIV/AIDS Reporting System (or equivalent) in accordance with
current practice. To address specific public health information needs, local sur-
veillance programs can cross-match HIV and AIDS surveillance data with other
public health data (e.g., tuberculosis data) and collect supplemental surveillance
data on all or a representative sample of cases. CDC will provide technical assis-
tance and recommend standardized surveillance methods to assist in collecting
supplemental surveillance information.
• On the basis of studies of coded identifier systems conducted in at least eight
states, published evaluations of name-based and code-based surveillance sys-
tems, and CDC’s assessment of the quality and reproducibility of the available
data, CDC has concluded that confidential name-based HIV/AIDS surveillance
systems are most likely to meet the necessary performance standards (
36,58,60–
67,89,90
), as well as to serve the public health purposes for which surveillance
data are required. Therefore, CDC advises that state and local surveillance pro-
grams use the same confidential name-based approach for HIV surveillance as is
currently used for AIDS surveillance nationwide. However, CDC recognizes that
some states have adopted, and others may elect to adopt, coded case identifiers
for public health reporting of HIV infection. CDC will provide technical assistance
to all state and local areas to continue or establish HIV/AIDS surveillance systems
and to evaluate their surveillance programs using standardized methods and cri-
teria whether they use name or coded identifiers.
• HIV and AIDS surveillance should be used to identify rare or previously unrecog-
nized modes of HIV transmission, unusual clinical or virologic manifestations,
and other cases of public health importance. Providers are the most likely and
timely source of identifying unusual laboratory or clinical cases. They are encour-
aged to promptly report atypical cases to local, state, or territorial public health
officials for follow-up. CDC will provide technical assistance to state and local
health departments conducting such investigations and will revise public health
recommendations based on the findings, as appropriate.
• HIV and AIDS case surveillance efforts should result in collection of data from all
private and public sources of HIV-related testing and care services. Laboratory-
initiated surveillance methods should identify all cases that meet the laboratory
reporting criteria for HIV infection and/or AIDS. However, these methods will
12 MMWR December 10, 1999
require follow-up with the provider to verify the infection status or clinical stage
and obtain complete demographic and exposure risk data. HIV-infected persons
who are initially tested anonymously are eligible to be reported to CDC’s
HIV/AIDS surveillance database only after they have had HIV infection diagnosed
in a confidential testing setting (e.g., by a health-care provider) and have test
results or clinical conditions that meet the HIV and/or AIDS reporting criteria.
• All state and local surveillance programs should regularly publish, in print
or electronically, aggregated HIV/AIDS surveillance data in a format that facili-
tates use of these data by federal, state, and local public health agencies,
HIV-prevention community planning groups and care-planning councils, aca-
demic institutions, providers and institutions that have reported cases,
community-based organizations, and the general public. Presentation of surveil-
lance data should be consistent with established policies for data release that
preclude the direct or indirect identification of a person with HIV infection or
AIDS. CDC will increase its efforts to coordinate requests for HIV/AIDS surveil-
lance data across federal government agencies to use state/local surveillance
resources efficiently. CDC will also develop specific guidelines for analyzing and
interpreting HIV/AIDS surveillance data.
• All state and local surveillance programs should conduct regular, ongoing
assessments of the performance of the surveillance system and redirect efforts
and resources to ensure timely reporting of complete, representative, and accu-
rate data. CDC will provide technical assistance and recommend standardized
evaluation methods to assist states in achieving the highest possible level of per-
formance and to promote comparability of data throughout the United States.
Minimum Performance Standards
• To provide accurate and timely data for monitoring HIV/AIDS trends and ensuring
a reliable measure of the number of persons in need of HIV-related prevention
and care services, state and local HIV/AIDS surveillance systems should use
reporting methods that provide case reporting that is complete (≥85%) and
timely (≥66% of cases reported within 6 months of diagnosis). In addition, evalu-
ation studies should demonstrate that the approach used to conduct surveillance
(i.e., name or coded identifier) must result in accurate case counts (≤5% duplicate
case reports and ≤5% incorrectly matched case reports). Finally, at least 85% of
reported cases or a representative sample should have information regarding
risk for HIV infection after epidemiologic follow-up is completed. All HIV/AIDS
surveillance systems should collect the recommended standard data in a reliable
and valid manner, allow matching to other public health databases (e.g., death
registries) to benefit specific public health goals, and allow identification and
follow-up of individual cases of public health importance.
• To assess the quality of HIV and AIDS case surveillance as specified in the per-
formance standards, states and local surveillance programs must conduct
periodic evaluation studies. CDC will recommend several evaluation methods to
enable states to select methods best suited to their program needs and
resources. States should also evaluate the representativeness of their HIV case
Vol. 48 / No. RR-13 MMWR 13
reports by monitoring the potential impact of HIV surveillance on test-seeking
patterns and behaviors and review the extent to which surveillance data are
being used for planning, targeting, and evaluating HIV-prevention programs and
services. The goal of these performance evaluations is to enhance the quality and
usefulness of surveillance data for public health action. During the next several
years (i.e., 2000–2002), CDC will assist states in transitioning to an integrated
HIV/AIDS surveillance system by evaluating current performance levels, institut-
ing revised program operations and policies as necessary, and then reassessing
performance. Following this transition period, CDC will evaluate and award pro-
posals for federal funding of state and local surveillance programs based on their
capacity to meet these performance standards. At that time, CDC will require that
recipients of federal funds for HIV/AIDS case surveillance adopt surveillance
methods and practices that will enable them to achieve the standards to ensure
that federal funds are awarded responsibly.
Recommended Security and Confidentiality Practices
• State and local programs should document their security policies and proce-
dures and ensure their availability for periodic review.
• State and local health departments should minimize storage and retention of
unnecessary or redundant paper or electronic reports and should review their
data-retention policies consistent with CDC technical guidelines (
73–75
). States
should consider and evaluate removing names from surveillance records when
they no longer serve the public health purpose for which they were collected.
Policies should provide the flexibility to remove cases that were reported in error
or that are determined not to be infected with HIV on follow-up. CDC will develop
guidance for confirming HIV-infection status as testing and vaccine technologies
evolve.
• State and local health departments should also review their confidentiality prac-
tices to determine whether additional protections should be established (e.g.,
before implementation of HIV case surveillance). States that plan to implement
HIV case surveillance should review their current confidentiality statutes to deter-
mine whether they need to be strengthened. The
Model State Public Health
Privacy Act
(
69
) should be considered by states in developing their statutory
protections of HIV/AIDS surveillance data. Confidentiality laws should protect
surveillance data that are transmitted (in a secure and confidential manner con-
sistent with CDC’s HIV/AIDS surveillance program requirements) to other public
health programs as part of evaluation studies or for follow-up of cases of special
public health importance. The penalties for violating privacy and security should
apply to all recipients of HIV/AIDS case surveillance information.
• To further enhance security and confidentiality of data, states are encouraged to
implement use of a double-key encryption and decryption system, in which iden-
tifying information encrypted by states using the first key can only be decrypted
for access using the second key. CDC will develop this option at the request of
states that wish to reassure HIV-infected persons that HIV and AIDS surveillance
data will be held confidentially and will be used only for specified public health
14 MMWR December 10, 1999
purposes. CDC will hold the second key under an Assurance of Confidentiality
under Section 308(d) of the Public Health Service Act, which governs how CDC
uses or releases surveillance data voluntarily shared with CDC by the states.
Under this assurance, CDC is prohibited from providing that key to a state plan-
ning to use HIV/AIDS surveillance data for non-public health purposes.
Minimum Security and Confidentiality Standards
The security and confidentiality policies and procedures of state and local surveil-
lance programs should be consistent with CDC standards for the security of HIV/AIDS
surveillance data (
73,74
). The minimum security criteria were established following
reviews of all state and numerous local health department HIV/AIDS surveillance pro-
grams. In general, the reviews documented that health departments have achieved a
high level of security and that most state health departments meet or exceed the mini-
mum standards. Beginning in 2000, CDC will require that recipients of federal funds
for HIV/AIDS surveillance establish the minimum security standards and include their
security policy in applications for surveillance funds (
73,74
). Examples of these stand-
ards include the following:
• Electronic HIV/AIDS surveillance data should be protected by computer encryp-
tion during data transfer. States should continue the established practice of not
including personal identifying information in HIV/AIDS surveillance data for-
warded to CDC.
• HIV and AIDS surveillance records should be located in a physically secured area
and should be protected by coded passwords and computer encryption.
• Access to the HIV/AIDS surveillance registry should be restricted to a minimum
number of authorized surveillance staff, who are designated by a responsible
authorizing official, have been trained in confidentiality procedures, and are
aware of penalties for unauthorized disclosure of surveillance information.
• Public health programs that receive HIV/AIDS information from matching of pub-
lic health databases should have security and confidentiality protections and
penalties for unauthorized disclosure equivalent to those for HIV/AIDS surveil-
lance data and personnel.
• Use of HIV/AIDS surveillance data for research purposes should be approved by
appropriate institutional review boards, and persons conducting the research
must sign confidentiality statements.
• HIV and AIDS surveillance data made available for epidemiologic analyses must
not include names or other identifying information. State and local data release
policies should ensure that the release of data for statistical purposes does not
result in the direct or indirect identification of persons reported with HIV infection
and AIDS.
• In the rare instance of a possible security breach of HIV/AIDS surveillance data,
state and local health departments should promptly investigate and report con-
firmed breaches to CDC to enable CDC to provide technical assistance to state
and local health departments, develop recommendations for improvements in
Vol. 48 / No. RR-13 MMWR 15
security measures, and provide oversight in monitoring changes in program
practices.
Relation to HIV-Prevention and HIV-Care Programs:
Recommended Practices
At the federal level, the primary function of HIV/AIDS surveillance is collecting
accurate and timely epidemiologic data for public health planning and policy. Conse-
quently, CDC is authorized to provide federal funds to states through surveillance
cooperative agreements, both to achieve the goals of the national surveillance pro-
gram and to assist states in developing their surveillance programs in accordance
with state and local laws and practices. Federal funds authorized for HIV/AIDS surveil-
lance are not provided to states for developing or providing prevention or treatment
case-management services; funds for such services are provided by CDC and other
federal agencies under separate authorizations.
Whether and how states establish a link between individual case-patients reported
to their HIV/AIDS surveillance programs and other health department programs and
services for HIV prevention and treatment is within the purview of the states. However,
in considering or establishing such linkages, CDC recommends the following:
• The implementation of HIV case surveillance should not interfere with HIV-
prevention programs, including those that offer anonymous HIV counseling and
testing services. Unless prohibited by state law or regulation, as a condition of
federal funding for HIV prevention under a separate authorization, CDC requires
that states and local areas provide anonymous HIV counseling and testing serv-
ices. CDC strongly recommends that states which prohibit anonymous HIV
testing change this practice, given the overriding public health objective of
encouraging persons to become aware of their HIV serologic status. CDC does
not view the availability of publicly funded anonymous counseling and HIV test-
ing as incompatible with the ability to conduct HIV case surveillance in the
population.
• HIV testing services should be offered for participation on a voluntary basis and
preceded by informed consent in accordance with local laws (
91
).
• Both public and private providers should refer persons in whom HIV infection
has been diagnosed to programs that provide HIV care, treatment, and compre-
hensive prevention case-management services.
• Provider-based referrals of patients to prevention and care services should
enable a timely, effective, and efficient means of ensuring that persons in whom
HIV infection has been diagnosed receive needed services.
• States should consult with providers, prevention- and care-planning bodies, and
public health professionals in developing the policies and practices necessary to
effect these linkages; should require that recipients of HIV/AIDS surveillance
information be subject to the same penalties for unauthorized disclosure
as HIV/AIDS surveillance personnel; and should evaluate the effectiveness of
this public health approach. Such an evaluation should ensure that the public
health objectives of such linkages are achieved without unnecessarily increasing
16 MMWR December 10, 1999
security and confidentiality risks to surveillance data or decreasing the accept-
ability of surveillance programs to health-care providers and affected
communities. Providers and affected communities, including HIV-prevention
community planning groups, should participate with health departments in plan-
ning and implementing surveillance strategies, as well as programs and services.
COMMENTARY
Surveillance Case Definition for HIV Infection and AIDS
The revised case definition for HIV infection in adults and children integrates
reporting criteria for HIV infection and AIDS in a single case definition and incorpo-
rates new laboratory tests in the laboratory criteria for HIV case reporting. The 2000
case definition for HIV infection includes HIV nucleic acid (DNA or RNA) detection tests
that were not commercially available when the AIDS case definition was revised in
1993. The revised case definition for HIV infection also permits states to report cases
to CDC based on the result of any test licensed for diagnosing HIV infection in the
United States. Although the reporting criteria generally reflect the recommendations
for diagnosing HIV infection, the HIV reporting criteria are for public health surveil-
lance and are not designed for making a diagnosis for an individual patient. The
laboratory criteria include the serologic HIV tests described in the clinical standards
for diagnosing HIV infection (
92–95
).
The pediatric HIV reporting criteria include criteria for monitoring all children with
perinatal exposures to HIV and reflect recent advances in diagnostic approaches that
permit the diagnosis of HIV infection during the first months of life. With HIV nucleic
acid detection tests, HIV infection can be detected in nearly all infants aged ≥1 month.
The timing of the HIV serologic and HIV nucleic acid detection tests and the number of
HIV nucleic acid detection tests in the definitive and presumptive criteria for HIV infec-
tion are based on the recommended practices for diagnosing infection in children
aged <18 months and on evaluations of the performance of these tests for children in
this age group (
30,77–88
).
The clinical criteria in the case definition for HIV infection are included to ensure the
complete reporting of cases with documented evidence of HIV infection or conditions
meeting the AIDS case definition. The AIDS-defining conditions are included as part of
the single case definition for HIV infection. In adults and adolescents aged ≥13 years,
criteria for presumptive and definitive AIDS-defining conditions have not been revised
since 1993 and continue to include the laboratory markers of severe HIV-related
immunosuppression and the opportunistic illnesses indicative of severe HIV disease,
which greatly increase mortality risks.
Effect of National HIV Case Surveillance on Reporting Trends
Changes in the HIV reporting criteria will have little effect on reporting trends in
states already conducting HIV case surveillance. However, the number of cases of HIV
infection reported nationally will increase primarily because of implementation of HIV
surveillance by the remaining states and local areas. Many of the states that will
implement HIV case surveillance in the future have high AIDS incidence rates. Similar
Vol. 48 / No. RR-13 MMWR 17
to the effect on AIDS surveillance trends after the implementation of the revised
reporting criteria in 1993, the initiation of HIV surveillance by additional states might
result in a sudden and large increase in HIV case reports (
96
). On the basis of CDC’s
estimate that approximately 220,000 HIV-infected persons without AIDS-defining con-
ditions had had HIV infection diagnosed in confidential testing settings and resided in
states that were not conducting HIV case surveillance at the end of 1996 (
46
), the
possibility exists that this number of persons could be reported with HIV infection
from these states in 2000. However, reporting of prevalent HIV infections is more likely
to be spread over several years, and the annual increases will most likely be more
modest. Initially, most case reports will represent persons whose HIV infection was
diagnosed before the implementation of HIV surveillance. As the reporting of preva-
lent cases of HIV infection reaches full implementation nationwide, the number of HIV
case reports will decrease, and case reports will increasingly represent persons with
recent diagnoses of HIV infection.
To facilitate interpretation of HIV surveillance data and given that CDC strongly pro-
motes continued availability of anonymous testing options, evaluations of HIV/AIDS
surveillance systems will include assessments of the representativeness of HIV case
surveillance data. These assessments will include special surveys to evaluate the
delays between HIV testing and entry to care. In addition, these evaluations will be
useful in determining the effectiveness of program efforts to refer persons into care
services after the diagnosis of HIV infection in anonymous testing settings.
AIDS cases have declined nationwide; however, because AIDS surveillance trends
are affected by the incidence of HIV infection, as well as the effect of treatment on the
progression of HIV disease, future AIDS trends cannot be predicted. AIDS surveillance
will continue to be important in evaluating access to care for different populations and
in identifying changes in trends that might signal a decrease in the effectiveness of
treatment. The long-term benefits of antiretroviral therapy and antimicrobial prophy-
laxis for AIDS-related illnesses continue to be defined. In addition, various factors
(e.g., access, adherence, treatment costs, and viral resistance) will influence the use
and effectiveness of these therapies and their effects on AIDS incidence and mortality
trends (
97–99
).
Because trends in new diagnoses of HIV infection are affected by when in the
course of disease a person seeks or is offered HIV testing, such trends do not reflect
the incidence of HIV infection in the population. In addition, because all HIV-infected
persons in the population might not have had the infection diagnosed, these data do
not represent total HIV prevalence in the population. Currently, interpretation of these
data is complicated by several factors. First, persons might have HIV infection diag-
nosed and later during the same calendar year have AIDS diagnosed, which can
complicate presentation of the data. Second, delays in reporting cases of HIV infection
tend to be shorter than for AIDS cases, necessitating development of stage-specific
statistical adjustments. Third, methods of imputation of exposure risk data for AIDS
cases have been developed based on historical patterns of reclassification after inves-
tigation, but comparable methods for cases of HIV infection are only recently available
at the national level. Finally, whether a trend in the number of new HIV diagnoses is
stable, increasing, or decreasing might reflect current or historical HIV transmission
patterns, changes in testing behaviors, and/or stage of the epidemic in the local geo-
graphic area.
18 MMWR December 10, 1999
Overall, in the United States, the incidence of HIV infection peaked approximately
15 years ago, and the annual number of HIV infections has been stable at approxi-
mately 40,000 since 1992, when CDC estimated the prevalence of HIV infection in the
range of 650,000–900,000 infected persons (
100,101
). Based on HIV and AIDS case
surveillance data, CDC estimates that the prevalence of HIV infection at the end of
1998 was in the range of 800,000–900,000 infected persons. Of these persons, approxi-
mately 625,000 (range: 575,000–675,000) had had HIV infection or AIDS diagnosed
(CDC, unpublished data, 1999). Because the annual number of new infections in recent
years is relatively lower than during the peak incidence years, over time the remaining
untested or anonymously tested infected persons will have HIV infection diagnosed
through test-seeking, targeted testing, entry to care, or progression of disease to
AIDS. Ultimately, the number of new diagnoses of HIV infection will decrease each
year as they increasingly represent the smaller pool of more recently infected per-
sons. Thus, in states that have been conducting HIV case reporting for several years,
the number of new diagnoses of HIV infection is expected to decrease, then stabilize
at a lower rate if the number of new infections remains stable.
For states that newly implement HIV reporting, a large bolus of reported prevalent
infections is expected to occur, followed by a decline in the annual number of new
cases until the number stabilizes at a lower level. Recently, since the impact of highly
active antiretroviral therapy on survival, the estimated number of new infections each
year probably exceeds the number of deaths, and the prevalence of HIV infection
might be increasing by a small proportion of total prevalence. Thus, during the transi-
tion period to nationwide HIV-infection reporting, measures of the combined
prevalence of HIV infection diagnoses and AIDS diagnoses will be most useful in pro-
jecting the need for resources for care and prevention. Trends in the numbers of new
cases reported will not provide immediate insights into the dynamics of the epidemic
because prevalent case reports represent a mixture of new and old HIV infections.
Within the next several years, however, all states will be able to characterize new diag-
noses of HIV infection or a representative sample by demographic and clinical
characteristics that will provide meaningful insights into actual HIV transmission pat-
terns and will have well-characterized the health and service needs of the population
of prevalent HIV-infected persons. CDC will develop analysis profiles, statistical
adjustments for reporting delays and imputation of risk data, and recommendations
for data presentation to assist states in analyzing and interpreting their HIV/AIDS sur-
veillance data during this transition period.
HIV/AIDS Surveillance Practices
Laboratories will be an increasingly important source of information from which
to initiate reporting. HIV infection is frequently diagnosed in the outpatient clinical
setting, and laboratory-initiated reporting will be particularly useful in identifying
outpatient sources of HIV testing (
89
) although contact with individual providers is
necessary to complete the reporting process. The routine collection of HIV and CD4
test data from laboratories and managed-care organizations promotes completeness
of reporting and may increase the simplicity and efficiency of initial case-finding
activities by local surveillance programs. Nonetheless, repeated testing of the same
persons results in multiple reports and necessitates labor-intensive follow-up to
Vol. 48 / No. RR-13 MMWR 19
eliminate duplicates. CDC is increasing its efforts to promote standards in laboratory
reporting and to facilitate the transfer of data from public health and commercial labo-
ratories to health departments.
Performance criteria for HIV and AIDS surveillance are necessary to ensure that
surveillance data are of sufficient quality to target prevention and care resources and
to detect emerging trends in the HIV epidemic. Evaluations of HIV and AIDS surveil-
lance programs have documented that areas should be able to meet these
performance criteria (
5,36,61–67,89,90
). According to these evaluations of name-
based surveillance systems, the completeness of HIV surveillance (from 79% to
approximately 95%) and AIDS surveillance (from 85% to approximately 95%) is high,
and reporting is timely with nearly one half of AIDS cases and three quarters of cases
of HIV infection reported to the national HIV/AIDS reporting system within 3 months of
diagnosis (
5
). CDC estimates that the duplication rate of cases of HIV infection
reported from different states to the national surveillance database was approxi-
mately 2%; for AIDS cases, the rate was approximately 3% (
5,36
). The performance
criteria also reflect the need for public health surveillance systems to identify and fol-
low-up on cases of public health importance.
On the basis of current evaluation studies of non-name-based case identifiers and
the current infrastructure of state and local health departments, name-based methods
for collecting and reporting public health data provide the most feasible, simple, and
reliable means for ensuring timely, accurate, and complete reporting of persons in
whom HIV infection or AIDS has been diagnosed. Confidential name-based reporting
also facilitates follow-up of perinatally exposed infants to determine their infection
status and of persons reported with HIV infection to determine progression to AIDS
and vital status (
36,42
). A name-based patient identifier allows providers to report
cases directly from their name-based medical records, facilitates elimination of dupli-
cate case reports, enables cross-matching of HIV and AIDS data with other name-
based public health data (e.g., tuberculosis surveillance), permits follow-up with
providers to collect information regarding risk for HIV infection and other data of pub-
lic health importance. Through follow-up with providers, the HIV/AIDS surveillance
system has provided an effective means to identify rare or unusual modes of HIV
transmission and infection with rare strains of HIV and to improve prevention of HIV-
related opportunistic illnesses (
102–106
). CDC will assist states in monitoring the
impact of changing medical interventions, epidemiology, and HIV case surveillance
policies on test- and care-seeking behaviors.
Security and Confidentiality of HIV and AIDS Surveillance
The revision of the case definition for HIV infection provides an opportunity to
review and strengthen state and local confidentiality laws and regulations. Although
state HIV/AIDS surveillance confidentiality laws and regulations adequately protect
privacy compared with the statutory protections of other health-care data, state
statutes differ in the degree of privacy protections afforded health information and the
criteria for permissible disclosures of personal information. Most state statutes
describe some permissible disclosures of public health information. To help ensure
uniform confidentiality protections, the Georgetown University Law Center developed
the
Model State Public Health Privacy Act
(
69
). Public health, legislative, legal,
and community advocacy representatives provided expert consultation. The model
20 MMWR December 10, 1999
legislative language protects confidential, identifiable information held by state and
local public health departments against unauthorized and inappropriate non-public
health uses but still allows public health officials to use surveillance information to
accomplish the public health objectives defined by the law (
69
). CDC recommends
that states planning to implement HIV case surveillance should consider adopting the
model legislation, if necessary, to strengthen the current level of protection of public
health data.
Although HIV/AIDS surveillance systems have exemplary records of security and
confidentiality, it is essential for all programs to identify ways to strengthen data pro-
tection because of a perceived greater sensitivity of HIV case surveillance compared
with that of AIDS case surveillance alone (
71
). Providing accurate public education
and factual media messages to inform vulnerable populations, as well as promoting
testing programs that facilitate referrals into treatment and prevention services, will
be important to ensure that test seeking and acceptance are not adversely affected as
additional states implement HIV case reporting. The revised security standards (
74
)
promote enhancements to further reduce any potential for disclosure of sensitive sur-
veillance data. CDC continues to conduct evaluations of methods to further enhance
data security, including the use of coding and encryption of data collected in the
HIV/AIDS reporting system.
HIV Prevention and Care
CDC has published guidelines concerning the provision and targeting of HIV coun-
seling and testing services
(29,41,107–111
) and provides support for most public
sources of HIV testing. The availability of anonymous HIV testing services might be
particularly important for persons who delay seeking testing because of a concern
that others might learn of their serologic status (
55
). Studies have documented that
the availability of anonymous HIV testing is associated with increased numbers of
persons seeking testing services (
112–115
). Anonymous HIV testing services are a
required element of federally supported prevention programs unless prohibited by
state law or regulation. Currently, 39 states, Puerto Rico, and the District of Columbia
provide anonymous HIV testing services.
CDC advises that the decision to refer persons reported to the surveillance system
to prevention and care services (e.g., partner counseling and referral services [PCRS])
be made at the local level. PCRS programs provide HIV counseling and testing to per-
sons who might be unaware of HIV risk exposures, and these services are a required
component of federally sponsored HIV-prevention programs (
116,117
). The provision
of such services to persons in whom HIV infection or AIDS has been diagnosed, espe-
cially those who receive services in publicly funded testing and clinic settings, is
conducted successfully by states regardless of whether they have implemented HIV
reporting (
118
). Referrals from surveillance to other health department services,
when they occur, should be established in a manner that ensures both the quality of
the surveillance data and the security of the surveillance system, as well as the quality,
confidentiality, and voluntary nature of HIV-prevention services (
119
). At the federal
level, the primary function of HIV/AIDS surveillance remains the provision of accurate
epidemiologic data for public health information, planning, and evaluation.
Persons in whom HIV infection has been diagnosed at either confidential or anony-
mous test sites should be promptly referred to facilities that provide confidential
Vol. 48 / No. RR-13 MMWR 21
HIV care. Recent studies have documented disparities in ensuring timely testing
and access to care by demographic, socioeconomic, and other factors (
120,121
). Al-
though not directly responsible for the delivery of medical care, CDC provides federal
direction for state and local programs that facilitate referral of HIV-infected persons
from counseling and testing centers and health education/risk-reduction programs to
HIV care facilities. CDC has developed guidelines to strengthen the system of referrals
between HIV testing sites and care programs, in part by increasing coordination with
the Health Resources and Services Administration and the Ryan White CARE Act
grantees (
122
). To provide further guidance, CDC has participated in developing
model contract language for Medicaid programs that serve persons with HIV infection
to ensure cooperation with public health authorities in case reporting and follow-up.
A well-developed and well-implemented HIV and AIDS case surveillance system is
integral to public health efforts to identify disparities, target programs and resources
to vulnerable populations, and assess the impact of these programs in reducing infec-
tion, disease, and premature death.
CDC is undertaking a national effort to further reduce perinatal HIV transmission in
the United States. This effort will incorporate HIV counseling and voluntary testing,
treatment, and outreach to pregnant women, especially those who are racial/ethnic
minorities and substance abusers, and will integrate prevention and treatment
services for women and children. Surveillance for perinatally HIV-exposed and HIV-
infected children will remain a critical measure of the effectiveness of this campaign
(
32,40,41,123,124
).
CONCLUSION
The implementation of a national surveillance network to include both HIV and
AIDS case reporting is a necessary response to epidemiologic trends and new stand-
ards for HIV care (
125–127
). Integrated HIV/AIDS surveillance programs will provide
data to characterize persons in whom HIV infection has been newly diagnosed, includ-
ing those with evidence of recent infection, persons with severe HIV disease (AIDS),
and those dying of HIV disease or AIDS. The revised HIV surveillance case definition
and the establishment of minimum performance standards will promote uniform case
ascertainment and will ensure that the surveillance data are of sufficient quality for
effective planning and allocation of resources for prevention and care programs.
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28 MMWR December 10, 1999
Appendix
Revised Surveillance Case Definition
for HIV Infection*
This revised definition of HIV infection, which applies to any HIV (e.g., HIV-1 or HIV-2),
is intended for public health surveillance only. It incorporates the reporting criteria for
HIV infection and AIDS into a single case definition. The revised criteria for HIV infec-
tion update the definition of HIV infection implemented in 1993 (
18
); the revised HIV
criteria apply to AIDS-defining conditions for adults (
18
) and children (
17,19
), which
require laboratory evidence of HIV. This definition is not presented as a guide to clini-
cal diagnosis or for other uses (
17,18
).
I.
In adults, adolescents, or children aged ≥18 months
†
, a reportable case of HIV in-
fection must meet at least one of the following criteria:
Laboratory Criteria
• Positive result on a screening test for HIV antibody (e.g., repeatedly reactive en-
zyme immunoassay), followed by a positive result on a confirmatory (sensitive
and more specific) test for HIV antibody (e.g., Western blot or immunofluores-
cence antibody test)
or
• Positive result or report of a detectable quantity on any of the following HIV
virologic (nonantibody) tests:
- HIV nucleic acid (DNA or RNA) detection (e.g., DNA polymerase chain reaction
[PCR] or plasma HIV-1 RNA)
§
- HIV p24 antigen test, including neutralization assay
- HIV isolation (viral culture)
OR
*Draft revised surveillance criteria for HIV infection were approved and recommended by the
membership of the Council of State and Territorial Epidemiologists (CSTE) at the 1998 annual
meeting (
11
). Draft versions of these criteria were previously reviewed by state HIV/AIDS
surveillance staffs, CDC, CSTE, and laboratory experts. In addition, the pediatric criteria were
reviewed by an expert panel of consultants. [External Pediatric Consultants: C. Hanson, M.
Kaiser, S. Paul, G. Scott, and P. Thomas. CDC staff: J. Bertolli, K. Dominguez, M. Kalish, M.L.
Lindegren, M. Rogers, C. Schable, R.J. Simonds, and J. Ward]
†
Children aged ≥18 months but <13 years are categorized as “not infected with HIV” if they
meet the criteria in III.
§
In adults, adolescents, and children infected by other than perinatal exposure, plasma viral
RNA nucleic acid tests should NOT be used in lieu of licensed HIV screening tests (e.g.,
repeatedly reactive enzyme immunoassay). In addition, a negative (i.e., undetectable) plasma
HIV-1 RNA test result does not rule out the diagnosis of HIV infection.
Vol. 48 / No. RR-13 MMWR 29
Clinical or Other Criteria (if the above laboratory criteria are not met)
• Diagnosis of HIV infection, based on the laboratory criteria above, that is docu-
mented in a medical record by a physician
or
• Conditions that meet criteria included in the case definition for AIDS (
17–19
)
II.
In a child aged <18 months, a reportable case of HIV infection must meet at least
one of the following criteria:
Laboratory Criteria
Definitive
• Positive results on two separate specimens (excluding cord blood) using one or
more of the following HIV virologic (nonantibody) tests:
- HIV nucleic acid (DNA or RNA) detection
- HIV p24 antigen test, including neutralization assay, in a child ≥1 month of age
- HIV isolation (viral culture)
or
Presumptive
A child who does not meet the criteria for definitive HIV infection but who has:
• Positive results on only one specimen (excluding cord blood) using the above
HIV virologic tests and no subsequent negative HIV virologic or negative HIV
antibody tests
OR
Clinical or Other Criteria (if the above definitive or presumptive laboratory criteria
are not met)
• Diagnosis of HIV infection, based on the laboratory criteria above, that is docu-
mented in a medical record by a physician
or
• Conditions that meet criteria included in the 1987 pediatric surveillance case defi-
nition for AIDS (
17,19
)
III.
A child aged <18 months born to an HIV-infected mother will be categorized for
surveillance purposes as “not infected with HIV” if the child does not meet the
criteria for HIV infection but meets the following criteria:
Laboratory Criteria
Definitive
• At least two negative HIV antibody tests from separate specimens obtained at
≥6 months of age
or
30 MMWR December 10, 1999
• At least two negative HIV virologic tests* from separate specimens, both of
which were performed at ≥1 month of age and one of which was performed at
≥4 months of age
AND
No other laboratory or clinical evidence of HIV infection (i.e., has not had any posi-
tive virologic tests, if performed, and has not had an AIDS-defining condition)
or
Presumptive
A child who does not meet the above criteria for definitive “not infected” status but
who has:
• One negative EIA HIV antibody test performed at ≥6 months of age and NO posi-
tive HIV virologic tests, if performed
or
• One negative HIV virologic test* performed at ≥4 months of age and NO positive
HIV virologic tests, if performed
or
• One positive HIV virologic test with at least two subsequent negative virologic
tests*, at least one of which is at ≥4 months of age; or negative HIV antibody test
results, at least one of which is at ≥6 months of age
AND
No other laboratory or clinical evidence of HIV infection (i.e., has not had any posi-
tive virologic tests, if performed, and has not had an AIDS-defining condition).
OR
Clinical or Other Criteria (if the above definitive or presumptive laboratory criteria
are not met)
• Determined by a physician to be “not infected”, and a physician has noted the
results of the preceding HIV diagnostic tests in the medical record
AND
NO other laboratory or clinical evidence of HIV infection (i.e., has not had any posi-
tive virologic tests, if performed, and has not had an AIDS-defining condition)
IV.
A child aged <18 months born to an HIV-infected mother will be categorized as
having perinatal exposure to HIV infection if the child does not meet the criteria for
HIV infection (II) or the criteria for “not infected with HIV” (III).
*HIV nucleic acid (DNA or RNA) detection tests are the virologic methods of choice to exclude
infection in children aged <18 months. Although HIV culture can be used for this purpose, it
is more complex and expensive to perform and is less well standardized than nucleic acid
detection tests. The use of p24 antigen testing to exclude infection in children aged <18 months
is not recommended because of its lack of sensitivity.
Vol. 48 / No. RR-13 MMWR 31
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