The Centers for Disease Control and Prevention (CDC), in
collaboration with other public health agencies and institutions, conducts
standardized unlinked prevalence surveys of human immunodeficiency virus
(HIV) infection in designated subgroups of the population as part of a
sentinel surveillance system to monitor the HIV epidemic in the United
States. This system also includes systematically collected national data
from ongoing mass HIV screening programs, which are periodically sent
without personal identifiers to CDC. These complementary surveys provide
standardized information to local and national public health officials on
the extent of HIV infection in geographic areas and population subgroups so
that education and prevention programs can be developed and evaluated. The
information can also be used to estimate the number of people who may
benefit from HIV-related care and treatment.
Of persons who know or suspect that they are infected with HIV or who are
at high risk for HIV infection, some may be more likely to participate in
studies of HIV prevalence and others may be less likely to do so. Unlinked
surveys are conducted to obtain estimates of HIV prevalence that are
unbiased by self-selection. Residual blood from specimens originally
collected for routine diagnostic purposes are tested for HIV antibodies
after all personal identifying information has been permanently removed.
Neither HIV test results nor risk information routinely obtained from
medical records can be linked to individuals. Thus, no interaction with
survey participants can take place solely for the purpose of the unlinked
surveys. All clinic sites that conduct unlinked surveys either provide or
offer referral for voluntary HIV counseling and testing.
In 1987, CDC began providing technical and financial assistance to state and
local health departments to conduct unlinked HIV prevalence surveys in
selected clinics serving populations at high risk for HIV infection. Surveys
were supported in 17 metropolitan areas during 1997 (Figure 1). Settings
included sexually transmitted disease (STD) clinics, drug treatment centers,
and adolescent medicine clinics. Clinics were chosen for participation in
the surveys by state and local health department personnel on the basis of
projected sample size, client demographic and behavioral characteristics,
and the ability and willingness of the staff to conduct surveys in
accordance with standardized protocols.
In addition to the unlinked surveys, CDC monitors results from HIV-antibody
mass screening programs. Since 1987, the U.S. Department of Labor has
provided CDC with HIV screening results for entrants to the Job Corps, a
federally funded job training program for economically and educationally
disadvantaged youth. The U.S. Department of Defense has provided CDC with
HIV screening results for civilian applicants to the military service since
1985. Personal identifiers are not sent to CDC.
This report summarizes 1997 data from unlinked prevalence surveys in
selected STD clinics, drug treatment centers, and adolescent medicine
clinics, as well as screening results for entrants to the Job Corps and
applicants for military service in the United States and Puerto Rico. The
appendix contains 1994 and 1995 summary data from the Survey of Childbearing
Women and the Sentinel Hospital Surveillance System for HIV Infection (both
of these surveys were concluded at the end of 1995).