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An inexpensive enzyme-linked immunosorbent assay method for human immunodeficiency virus type 1 quantitation, ultrasensitive p24 antigen assay (Up24), was compared with RNA viral load assay (VL). Up24 had 100% sensitivity of detection at a viral load of >/=30,000, with sensitivity of 46.4% at a viral load of <30,000 (232 specimens from 65 seropositive subjects). The assay was highly reproducible, with excellent correlation between duplicates and among three laboratories.

Most HIV surveillance has been performed through serologic surveys in relatively stable, accessible populations. Similar surveillance, with or without counseling and testing, in populations that are hard-to-reach, presents logistical challenges, including the selection of laboratory testing strategy and algorithm. The advent of rapid serologic assays for HIV now allows for on-site testing, including confirmatory testing, and rapid provision of test results and counseling. The possibility of only a single contact makes repeat sampling, which current diagnostic testing recommendations include, difficult. To address the logistical complexities in surveillance in hard-to-reach populations and the increased availability of rapid tests, we propose adapting the testing strategies for HIV of the World Health Organization/the joint United Nations Programme on HIV/AIDS in order to facilitate this surveillance, including, where carried out, the provision of test results back to individuals. The choice of enzyme-linked immunosorbent assay (ELISA) versus rapid testing for these settings is discussed, as is the choice of specimen--blood, oral fluid, or urine. Three appendices summarize: (1) test algorithms for the various testing strategies; (2) advantages and disadvantages of ELISA and of rapid test formats, and (3) the characteristics and status of currently available rapid HIV tests. We also discuss the potential application of the recently developed 'detuned' methodology for estimating HIV incidence in hard-to-reach populations.

Many studies have shown a positive association between both migration and temporary expatriation and HIV risk. This association is likely to be similar or even more pronounced for forced migrants. In general, HIV transmission in host-migrant or host-forced-migrant interactions depends on the maturity of the HIV epidemic in both the host and the migrant population, the relative seroprevalence of HIV in the host and the migrant population, the prevalence of other sexually transmitted infections (STIs) that may facilitate transmission, and the level of sexual interaction between the two communities. Complex emergencies are the major cause of mass population movement today. In complex emergencies, additional factors such as sexual interaction between forced-migrant populations and the military; sexual violence; increasing commercial sex work; psychological trauma; and disruption of preventive and curative health services may increase the risk for HIV transmission. Despite recent success in preventing HIV infection in stable populations in selected developing countries, internally displaced persons and refugees (or forced migrants) have not been systematically included in HIV surveillance systems, nor consequently in prevention activities. Standard surveillance systems that rely on functioning health services may not provide useful data in many complex emergency settings. Secondary sources can provide some information in these settings. Little attempt has been made, however, to develop innovative HIV surveillance systems in countries affected by complex emergencies. Consequently, data on the HIV epidemic in these countries are scarce and HIV prevention programs are either not implemented or interventions are not effectively targeted. Second generation surveillance methods such as cross-sectional, population-based surveys can provide rapid information on HIV, STIs, and sexual behavior. The risks for stigmatization and breaches of confidentiality must be recognized. Surveillance, however, is a key component of HIV and STI prevention services for forced migrants. It is required to define the high risk groups, target interventions, and ultimately decrease HIV and STI transmission within countries facing complex emergencies. It is also required to facilitate regional control of HIV epidemics.

Objectives: To describe epidemiologic patterns and trends in HIV infection in Vietnam from 1996 through 1999, and to summarize the national response to the epidemic., Methods: We reviewed nationwide HIV case reports, and we analyzed annual seroprevalence among different sentinel populations in 21 provinces, using the chi2 test for linear trend to assess trends in HIV prevalence. HIV prevention efforts were also reviewed., Results: Through 1999, 17,046 HIV infections, including 2947 AIDS cases and 1523 deaths had been reported in Vietnam. The cumulative incidence rate for the country was 22.5 per 100,000 population. Injection drug users (IDUs) represented 89.0% of all those for whom risk was reported before 1997 and 88.0% in the period 1997 to 1999. In 1999, HIV prevalence rates among IDUs ranged by province from 0% to 89.4%. Significantly increasing HIV trends among IDUs (p <.05) were found in 14 of the 21 sentinel provinces during 1996 to 1999. HIV prevalence among commercial sex workers (CSWs) ranged from 0% to 13.2%, increased significantly in 6 of 21 provinces. In 1999, prevalence among pregnant women, blood donors, and military recruits were 0.12%, 0. 20% and 0.61%, respectively. Major prevention activities include mass information; peer education and outreach among groups at increased risk; availability of low-cost syringes and condoms through pharmacies; needle exchange pilot projects; widely available treatment for sexually transmitted diseases; antibody screening of blood for transfusion; and free medical treatment at government hospitals., Discussion: The HIV epidemic continues to evolve rapidly, intensifying among IDUs and increasing among CSWs. Serosurveillance indicators of HIV in the population at large continue to indicate the relatively slow extension beyond those at highest risk. Immediate, intensive preventions in high-risk groups may decelerate expansion to the broader population.

To better characterize the virus isolates associated with the HIV-1 epidemic in Uganda, 100 specimens from HIV-1-infected persons were randomly selected from each of two periods from late 1994 to late 1997. The 200 specimens were classified into HIV-1 subtypes by sequence- based phylogenetic analysis of the envelope (env) gp41 region; 98 (49%) were classified as env subtype A, 96 (48%) as D, 5 (2.5%) as C, and 1 was not classified as a known env subtype. Demographic characteristics of persons infected with the two principal HIV-1 subtypes, A and D, were very similar, and the proportion of either subtype did not differ significantly between early and later periods. Our systematic characterization of the HIV-1 epidemic in Uganda over an almost 3-year period documented that the distribution and degree of genetic diversity of the HIV subtypes A and D are very similar and did not change appreciably over that time.

Objective: To assess whether HIV-2 infection protects against HIV-1 infection by comparing the rate of HIV-1 seroconversion among HIV-negative and HIV-2-seropositive women followed in a cohort study in Abidjan, Côte d'Ivoire., Design: Prospective cohort study, Methods: HIV seroconversion was assessed in 266 HIV-seronegative, 129 HIV-1-seropositive, and 127 HIV-2-seropositive women participating in a closed cohort study of mother-to-child transmission of HIV conducted during 1990-1994. Participants were seen every 6 months, and blood samples were obtained. All blood samples were screened for HIV antibodies by enzyme immunoassay (EIA) and confirmed by line immunoassay (LIA) and Western blot. Among women who were HIV-seronegative at enrolment, seroconversion was defined as new EIA-reactivity confirmed on LIA and Western blot. Among HIV-1- or HIV-2-seropositive women, seroconversion to dual reactivity was defined as new dual reactivity on the LIA that was confirmed by reactivity on both HIV-1- and HIV-2-monospecific EIA., Results: Five HIV-seronegative women became HIV-1-seropositive [seroconversion rate, 1.1 per 100 person-years; 95% confidence interval (CI), 0.3-2.5), and none became HIV-2-seropositive. No HIV-1-seropositive women became HIV-1/2 dually reactive, whereas six HIV-2-seropositive women acquired HIV-1 seroreactivity and thus became HIV-1/2 dually reactive (seroconversion rate 2.9 per 100 person-years; 95% CI, 1.1-6.3). HIV-2-seropositive women were more likely to acquire HIV-1 seroreactivity than were HIV-seronegative women (rate ratio, 2.7; 95% CI, 0.7-11.2), but this difference was not statistically significant (P>0.15)., Conclusion: HIV-2 infection does not appear to protect against HIV-1 infection.

The AIDS Information Center (AIC) was established in Kampala, Uganda in 1990 in response to increasing interest by members of the general public who wished to know their HIV serostatus. By 1996, >300,000 clients had been seen. HIV serologic testing was performed at a central laboratory and results reported back to AIC after 2 weeks. Approximately 25% of clients failed to learn their HIV serostatus as a result of failure to return or late arrival of results. To address these issues, AIC carried out an evaluation of 3 rapid HIV assays, Sero-Strip, SeroCard, and Capillus, against a standard criterion to identify a testing algorithm that could be used as an on-site confirmatory testing strategy. The study was carried out over a period of 5 working days and 325 clients were seen. An algorithm was identified, which gave no indeterminate results with unambiguously positive or negative specimens, which was 100% sensitive and specific, and which could be integrated with minimal disruption into existing counseling procedures. All clients left AIC knowing their HIV serostatus and having spent <2 hours at the Center. The results of this evaluation demonstrate that "same-day" results can be provided in counseling and testing settings without compromising the quality of counseling or the accuracy of HIV testing.

Objective: Previous data, based on a small sampling of convenience, reported subtypes A, B, C, D, and G in Uganda, but neither the extent nor the proportion of these subtypes could be evaluated. To establish correctly the prevalence and distribution of HIV-1 subtypes, we analysed viral clades in 739 HIV-1-seropositive specimens from different areas of Uganda., Methods: Blood specimens from 1100 patients were collected in five districts of Uganda. Within this collection, 929 HIV-1-seroreactive samples underwent analysis of viral DNA, and 739 were selected for further subtyping in env or pol regions., Results: Using a combination of subtype A- and D-specific probes to C2-V3 region and DNA sequencing, HIV-1 env subtypes were determined in 594 specimens: 341 were of subtype A (57.4%), 250 of subtype D (42.1%), and three of subtype C (0.5%). Sixty-two samples showed reactivity with both probes, suggesting potential mixed infections, cross-reactivity to probes, or possibly other subtypes. Subsequent sequence analysis of 19 randomly selected specimens revealed subtypes A (n = 4), D (n = 12), and C (n = 3). Sequence analysis of the 27 samples chosen from the remaining 83 samples, which could be amplified only with viral gp41 or protease gene primers, classified them as subtypes A (n = 13) and D (n = 14). No significant clinical, demographic, or geographic differences were found between HIV-1 infections with viruses of subtypes A and D, despite considerable genetic diversity within these clades., Conclusions: This is the first major population-based study of the prevalent HIV-1 strains in an African country selected for vaccine trials. The subtyping methods we describe should be of use to investigators seeking to conduct large-scale screening for HIV variants in other populations.

The CDC Family of Surveys is a national serologic surveillance system set up to characterize the extent of human immunodeficiency virus (HIV) infection in the United States. The now Centers for Disease Control and Prevention (CDC) and participating State and local health departments began the system in 1987. HIV seroprevalence data are collected by unlinked (anonymous) surveys of particular components of the population that include childbearing women; clients of sexually transmitted disease clinics; injecting drug users; tuberculosis patients; and several special populations, such as adolescents, prisoners, and homeless persons. The data obtained have been used extensively on both national and local levels to assist HIV-prevention programs. Data from the surveys have been used to identify specific demographic groups at risk for HIV infection so that health education programs may be planned and made available to them in clinical settings. Local serosurvey results have been used in planning and implementing prevention programs and in planning health services for HIV-positive persons. The completeness, or coverage, of HIV counseling and testing programs has been evaluated by comparing seroprevalences among clients tested voluntarily with those tested in the unlinked survey. Survey data are used in formulating recommendations and standards of care for health practitioners, in allocating resources, and in carrying out long-range planning for HIV prevention and treatment services for at-risk groups. Such data are essential to the decision-making process in forming public health policy and recommending practices involving the HIV epidemic.

The Centers for Disease Control and Prevention has developed guidelines for determining HIV seroprevalence among patients seeking medical care at acute-care hospitals. The guidelines enable hospital staff members to perform a simple, rapid, and inexpensive survey to determine seroprevalence among the patient population, protecting the anonymity of those who are tested. The guidelines are based on national experience with large-scale anonymous, unlinked HIV serosurveys. The data from a rapid assessment survey are particularly useful for evaluating the need to provide routine, voluntary HIV counseling and testing and treatment for HIV infection. Beyond that, such data can be used in targeting education efforts, in reinforcing the use of appropriate universal precautions, in resource allocation, and in determining the need for further studies of HIV infection among the population in the hospital catchment area.

Human immunodeficiency virus, type 1 (HIV), seroprevalence studies are needed to determine the level and trends of HIV infection among women attending family planning, abortion, and prenatal care clinics in the United States. A review of published and unpublished studies showed that HIV seroprevalence among women attending women's health clinics was 0 to 2.6 percent, although the studies were difficult to compare because of differences in methodology. The Centers for Disease Control, in association with State and local health departments, has developed a standardized protocol to determine HIV seroprevalence among women attending women's health clinics in selected metropolitan areas. Blinded HIV serosurveys (serologic test results not identified with a person) are being conducted annually in selected sentinel clinics in order to obtain estimates of HIV seroprevalence unbiased by self-selection, as well as to monitor trends in infection among clients attending these clinics. In areas with high HIV seroprevalence, nonblinded serosurveys (in which clients voluntarily agree to participate) will be used to assess behaviors that may place women at increased risk of exposure to HIV. Data from the surveys can be used in developing age-specific and culturally appropriate AIDS educational materials, assessing the amount and type of counseling activities required, and evaluating acquired immunodeficiency syndrome (AIDS) prevention activities. The information will provide epidemiologic data to complement the results of other surveys in characterizing the scope of HIV infection among women of childbearing age in the United States.

Symptomatic tuberculosis (TB) can occur as an opportunistic disease in immunosuppressed persons who are infected with human immunodeficiency virus (HIV) and who have been previously infected with Mycobacterium tuberculosis. Increases in TB cases have occurred in areas which have reported large numbers of cases of the acquired immunodeficiency syndrome (AIDS), and a high proportion of these TB cases have been HIV seropositive. Therefore, increasing numbers of HIV-infected persons may be found in TB clinics and hospitals. HIV serologic surveys in TB clinics and hospitals providing clinical services to TB patients are needed to assess the local prevalence of HIV infection in TB patients and the consequent need for public health intervention to prevent further spread of HIV and TB infection. The Centers for Disease Control (CDC), in collaboration with State and local health departments, has initiated HIV surveillance of patients with confirmed and suspected TB in TB clinics and hospitals in the United States. Blinded (serologic test results not linked to identifiable persons) HIV seroprevalence surveys are conducted in sentinel TB clinics and hospitals that provide TB clinical services each year to obtain estimates of the level of HIV infection in TB patients and to follow trends in infection over time. Nonblinded (voluntary) surveys will also be conducted to evaluate behaviors that have placed TB patients at risk for or protected them against HIV infection. Data from these surveys will be used to target education and prevention and control programs for TB and HIV infection and to monitor changes in behavior in response to such programs.

Sharing of equipment used to inject illicit drugs intravenously is a risk factor for human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS). Systematic surveillance of HIV infection among intravenous drug users (IVDUs) in the United States is essential to monitor the HIV epidemic and to target and evaluate prevention programs for IVDUs and their partners. The most accessible segment of the largely covert population of IVDUs are those in drug treatment programs. In collaboration with State and local health departments and drug abuse treatment agencies, the Centers for Disease Control is conducting blinded (serologic test results not linked to identifiable persons) and nonblinded (in which clients voluntarily agree to participate) surveys of IVDUs entering drug treatment in 39 U.S. metropolitan areas. The same protocol is used in all participating drug treatment centers. Blinded surveys will be carried out annually to determine HIV seroprevalence rates in eligible IVDUs entering drug treatment and to monitor trends over time. Each year, nonblinded surveys of IVDUs entering drug treatment will assess self-reported drug use and sexual behaviors to help design educational interventions and to detect changes in behavior over time. This sentinel surveillance system, using a standardized methodology, will provide the best national and regional data available on the seroprevalence of HIV among IVDUs and the relationships of drug use, sexual behaviors, and HIV serologic status of IVDUs.

The Centers for Disease Control, in cooperation with State and local health departments, is conducting human immunodeficiency virus, type 1 (HIV), seroprevalence surveys, using standard protocols, in sexually transmitted disease (STD) clinics in selected metropolitan areas throughout the United States. The surveys are blinded (serologic test results not identified with a person) as well as nonblinded (clients voluntarily agreeing to participate). STD clinics are important sentinel sites for the surveillance of HIV infection because they serve persons who are at increased risk as a result of certain behaviors, such as unprotected sex, homosexual exposure, or intravenous drug use. HIV seroprevalence rates will be obtained in the sentinel clinics each year so that trends in infection can be assessed over an extended period of time. Behaviors that place clients at risk for infection, or protect against infection, are being evaluated in voluntary, nonblinded surveys to define groups for appropriate interventions and to detect changes in response to education and prevention programs. Although inferences drawn from the surveys are limited by the scope of the clinics and clients surveyed, HIV trends in STD clinic client populations should provide a sensitive monitor of the course of the acquired immunodeficiency syndrome (AIDS) epidemic among persons engaging in high-risk sexual behaviors.

A seroprevalence survey of human immunodeficiency virus (HIV) among childbearing women is being conducted in 43 States and Territories as one of the family of HIV seroprevalence surveys. This blinded survey, in which serologic test results are not linked to identifiable persons, uses neonatal dried blood specimens on filter paper to test for maternal antibodies to HIV. This survey provides relatively unbiased estimates of prevalence of HIV infection in the population of women delivering live children during given survey periods, by month or quarter of delivery, geographic area, and demographic subgroup. This objective will be met while protecting the integrity and efficient conduct of neonatal screening programs and ensuring patient anonymity. Information from this survey will be used to (a) assess the levels and trends of HIV infection in women and infants, (b) help develop and evaluate prevention programs, and (c) project the number of women and children who will develop HIV infection and the acquired immunodeficiency syndrome (AIDS) and will require health care and social services in the future.

Planning for health and social services and for prevention programs requires predicting the number of AIDS cases likely to be diagnosed during the next several years and estimating the prevalence of HIV infection. Extrapolating from recent AIDS incidence data, we estimate that 365,000 AIDS cases will be diagnosed in the United States through 1992 (68% prediction interval, 205,000 to 440,000). Both recent HIV seroprevalence surveys and historical AIDS incidence are consistent with the U.S. Public Health Service estimate that 1.0 to 1.5 million persons in the United States are now infected with human immunodeficiency virus (HIV). Although current estimates of future AIDS cases and of current prevalence of HIV infection are somewhat uncertain, better statistical estimation procedures are being developed, and current surveys will provide additional data on HIV prevalence in the United States within the next several years.

Many of the conditions no doubt have already improved in those areas where international relief efforts are under way. The comments made here are based on observations by my colleagues and myself during the emergency phase of the famine and refugee crises and perhaps should be considered more as lessons learned that are better applied to newly emerging situations than to those relief efforts already in progress. In summary, the highest priority emergency health requirements identified during the current crisis have been, in my opinion, the provision of food and supplementary and therapeutic feeding, measles immunization, vitamin A prophylaxis, and oral rehydration therapy, plus the two management issues--rapid needs assessment with continued monitoring and adequate allocation of resources to prevention and control activities. One final note--from discussions with colleagues who were involved in the 1973-74 drought and famine in Africa, this crisis appears to be a repeat. A comprehensive, long-term approach would be beneficial so that these emergency responses are no longer necessary.

A comprehensive, multifaceted approach to HIV surveillance is needed to provide the information necessary for public health management and policy. Because HIV infection is not readily or uniformly ascertained, survey methods and sentinel surveillance approaches must be used. At least some of the surveys must be blinded, that is, anonymous and unlinked to identifiable persons, to avoid the uninterpretable impact of self-selection bias that could lead to both significant underestimates and occasional overestimates of HIV prevalence. Other surveys must be nonblinded, with careful interviews of volunteer participants to evaluate risk factors for HIV infection. These various surveys must continue over time to evaluate trends in infection. A comprehensive family of complementary HIV surveys and studies and a national household-based HIV seroprevalence survey have been undertaken by the Public Health Service in collaboration with other Federal agencies, State and local health departments, blood collection agencies, and medical research institutions. These projects focus on accessible segments of the general population, childbearing women, persons at high risk for HIV, and persons in special settings such as prisons and colleges. This comprehensive surveillance approach will help monitor the levels and trends of HIV infection in the United States and help prioritize, target, and evaluate HIV prevention activities.

By the end of 1987, nearly 50,000 cases of acquired immunodeficiency syndrome (AIDS) had been reported since 1981, 20,745 in the past year alone. Black and Hispanic adults and children have reported rates 3 to 12 times as high as whites. This can be largely attributed to higher reported rates in black and Hispanic intravenous (IV) drug abusers, their sex partners, and infants. In 1986, reported AIDS deaths increased adult male and female mortality in the United States by an estimated 0.7 and 0.07%, respectively, with much greater increases in selected age groups or areas of the country. The greatest variation in infection with the human immunodeficiency virus (HIV) (0 to 70%) has been found in surveys of IV drug abusers, while surveys of homosexual men reveal infection rates of 20 to 50%. Infection with HIV ranged from 0 to 2.6% in limited sexually transmitted disease clinic surveys of heterosexual men and women without a history of IV drug abuse or known sexual contact with persons at increased risk. The modes of HIV transmission are now well understood, but a large amount of biologic variability in efficiency of transmission remains to be explained. The period between initial infection with HIV and the development of AIDS is variable, but the risk for disease progression increases with duration of infection.