Prostitution and the sex discrepancy in reported number of sexual partners.

One of the most reliable and perplexing findings from surveys of sexual behavior is that men report substantially more sexual partners than women do. We use data from national sex surveys and studies of prostitutes and their clients in the United States to examine sampling bias as an explanation for this disparity. We find that prostitute women are underrepresented in the national surveys. Once their undersampling and very high numbers of sexual partners are factored in, the discrepancy disappears. Prostitution's role in the discrepancy is not readily apparent because men are reluctant to acknowledge that their reported partners include prostitutes.

HIV seroprevalence and risk factors among clients of female and male prostitutes.

OBJECTIVES: To document the HIV and STD infection rates among clients of female (CFP) and clients of male prostitutes (CMP) and to identify the risk factors for HIV among CFP and CMP. METHODS: Structured interviews were conducted with 82 CMP and 69 CFP in 1990 and 1991 in Atlanta, Georgia, U.S.A. Blood samples were tested for HIV, syphilis, and hepatitis B. RESULTS: The HIV-positive rate was 36.6% among CMP and 2.9% among CFP. Syphilis seromarkers were found in 15.9% of CMP and 10.1% of CFP; hepatitis B seromarkers were identified in 58.0% of CMP and 24.6% of CFP. Key risk factors for HIV among CMP included serologic history of syphilis, serologic history of hepatitis B, receptive anal sex with a male prostitute, ever injecting drugs, ever using crack cocaine, and little education. CFP had no significant risk factors for HIV in the logistic analysis. CONCLUSIONS: Several studies have focused on risk factors for HIV among female and male prostitutes; however, research on their clients has been limited. Although HIV infection rates among CFP are relatively low, their infection rate for syphilis and hepatitis warrants serious health education efforts. Even more critical are harm-reduction programs targeting CMP. Generic health and HIV risk reduction messages on heterosexual transmission might be insufficient.

Social network dynamics and HIV transmission.

OBJECTIVE: To prospectively study changes in the social networks of persons at presumably high risk for HIV in a community with low prevalence and little endogenous transmission. METHODS: From a cohort of 595 persons at high risk (prostitutes, injecting drug users, and sexual partners of these persons) and nearly 6000 identified contacts, we examined the social networks of a subset of 96 persons who were interviewed once per year for 3 years. We assessed their network configuration, network stability, and changes in risk configuration and risk behavior using epidemiologic and social network analysis, and visualization techniques. RESULTS: Some significant decrease in personal risk-taking was documented during the course of the study, particularly with regard to needle-sharing. The size and number of connected components (groups that are completely connected) declined. Microstructures (small subgroups of persons that interact intensely) were either not present, or declined appreciably during the period of observation. CONCLUSIONS: In this area of low prevalence, the lack of endogenous transmission of HIV may be related in part to the lack of a network structure that fosters active propagation, despite the continued presence of risky behaviors. Although the relative contribution of network structure and personal behavior cannot be ascertained from these data, the study suggests an important role for network configuration in the transmission dynamics of HIV.

Health education and promotion for STD prevention: lessons for the next millennium.

OBJECTIVE: To review the evolution of health promotion for STD prevention. MAIN OBSERVATIONS: Information and education programmes were provided at the beginning of the 20th century to warn the public about the dangers of venereal infection and to support the medical model of case identification and case management under the care of qualified physicians. The public health approach offered advice about chemical, chemotherapeutic, and barrier prophylaxis, but avoided the issue of social prophylaxis. With the failure of antimicrobial agents to eradicate syphilis in the 1960s, rapid increases of viral sexually transmitted diseases (STDs) and resistant strains of gonorrhoea in the 1970s, and the discovery of AIDS in the 1980s, alternatives to the traditional public health approach were sought and supported with a modest increase of resources. Three major innovations have been introduced to STD prevention as a result: social marketing, community involvement, and behaviour change programmes based on social and psychological concepts and theoretical models. CONCLUSIONS: Health promotion for STD prevention in the future will be characterised by careful assessments of the social and behavioural determinants of sexual risk taking, development and implementation of targeted interventions designed to reduce risk taking, and evaluation of social and behavioural interventions for improvements in STD prevention.

Mapping a social network of heterosexuals at high risk for HIV infection.

OBJECTIVE: To determine how heterosexuals at risk for HIV infection interconnect in social networks and how such relationships affect HIV transmission. DESIGN: Cross-sectional study with face-to-face interviews to ascertain sociosexual connections; serologic testing. PARTICIPANTS: Prostitute women (n = 133), their paying (n = 129) and non-paying (n = 47) male partners; injecting drug users (n = 200) and their sex partners (n = 41). Participants were recruited in sexually transmitted disease and methadone clinics, an HIV-testing site, and through street outreach in Colorado Springs, Colorado, USA. MAIN OUTCOME MEASURES: Reported behaviors, risk perceptions, sociosexual linkages, and HIV prevalence. RESULTS: Respondents were well informed, but reported engaging in high-risk behaviors frequently. Nevertheless, over 70% of respondents perceived themselves to be at low risk for HIV infection. The 595 respondents identified a social network of 5162 people to which they belonged. Network analytic methods indicated 147 separate connected components of this network; eight of the 19 HIV-positive individuals in the network were located in smaller components remote from the largest connected component. CONCLUSION: The isolated position of HIV-positive individuals may serve as a barrier to HIV transmission and may account for the lack of diffusion of HIV in heterosexual populations in this region. Network analysis appears useful for understanding the dynamics of disease transmission and warrants further development as a tool for intervention and control.

Social networks and infectious disease: the Colorado Springs Study.

The social network paradigm provides a set of concepts and methods useful for studying the structure of a population through which infectious agents transmitted during close personal contact spread, and an opportunity to develop improved disease control programs. The research discussed was a first attempt to use a social network approach to better understand factors affecting the transmission of a variety of pathogens, including hepatitis B virus (HBV) and human immunodeficiency viruses (HIV), in a population of prostitutes, injecting drug users (IDU) and their personal associates in a moderate-sized city (Colorado Springs, CO). Some of the challenges of studying large social networks in epidemiological research are described, some initial results reported and a new view of interconnections in an at risk population provided. Overall, for the first time in epidemiologic research a large number of individuals (over 600) were found connected to each other, directly or indirectly, using a network design. The average distance (along observed social relationships) between persons infected with HIV and susceptible persons was about three steps (3.1) in the core network region. All susceptibles in the core were within seven steps of HIV infection.

AIDS in Colorado Springs: is there an epidemic?

OBJECTIVE: To analyze trends and patterns of HIV infection in a medium-sized community in the United States. METHODS: Surveillance for AIDS and HIV infection was conducted by private physicians, military and public clinics, and blood and plasma donation centers. HIV-positive individuals were contacted and asked to refer their sex and injection partners for HIV-antibody testing. Prostitutes, injecting drug users and their sex partners were studied. Selected physicians were surveyed to assess under-reporting. RESULTS: The 740 HIV-infected adults (67 with documented seroconversion) included 506 with no evidence of AIDS, 58 living with AIDS, and 176 who had died. Of the 126 patients cared for by local physicians, 107 (85%) had been reported. No major changes in behavioral risk factors or increases in the number of HIV-infected individuals occurred between 1986 (128) and 1992 (95). CONCLUSIONS: Characteristics of individuals at risk and incidence of HIV infection have remained stable from 1981 to 1992. Analysis of data from the comprehensive surveillance and control program established in Colorado Springs in response to the AIDS epidemic suggests that, unlike the nation's epicenters, HIV incidence in this location is neither widespread nor rapidly increasing. The age distribution of reported cases is slowly increasing, and the ratio of newly reported cases to deaths is declining, implying stable or decreasing incidence; deaths may soon exceed new cases. Using data routinely available to public health officials, we conclude that the epidemiologic picture of AIDS--like the clinical one--must be heterogeneous, and that rational planning for the impact of AIDS should be based on the collection and analysis of local data.

Structuring HIV prevention service delivery systems on the basis of social science theory.

In order to identify the optimal configuration of HIV prevention programs, it is necessary to examine different theoretical models of behavior change. Cognitive/decision-making theories of human behavior change are compared to social learning theories vis-a-vis their influence on the structure of service delivery systems. Cognitive/decision-making theories ascribe behavior change to the provision of new information and favor the development of homogeneous interventions providing clients with information about risk behaviors. These interventions are easily standardized across delivery sites and various target populations. Social learning theories view behavior change as a series of stages and recognize the influence of sociocultural variables. They favor multiple heterogeneous interventions in a variety of settings, with the provision of skills training as well as information. Ongoing HIV prevention research indicates that social learning theories provide a more accurate paradigm of human behavior change for the complex behaviors related to HIV risk. Public health agencies must therefore continue to strengthen organizational and referral relationships with community-based organizations that can provide the specialized prevention interventions called for by social learning theory. This will require ongoing collaboration and technical assistance.

Course of HIV-I infection in a cohort of homosexual and bisexual men: an 11 year follow up study.

OBJECTIVE--To characterise the natural history of sexually transmitted HIV-I infection in homosexual and bisexual men. DESIGN--Cohort study. SETTING--San Francisco municipal sexually transmitted disease clinic. PATIENTS--Cohort included 6705 homosexual and bisexual men originally recruited from 1978 to 1980 for studies of sexually transmitted hepatitis B. This analysis is of 489 cohort members who were either HIV-I seropositive on entry into the cohort (n = 312) or seroconverted during the study period and had less than or equal to 24 months between the dates of their last seronegative and first seropositive specimens (n = 177). A subset of 442 of these men was examined in 1988 or 1989 or had been reported to have developed AIDS. MAIN OUTCOME MEASURES--Development of clinical signs and symptoms of HIV-I infection, including AIDS, AIDS related complex, asymptomatic generalised lymphadenopathy, and no signs or symptoms of infection. MEASUREMENTS AND MAIN RESULTS--Of the 422 men examined in 1988 or 1989 or reported as having AIDS, 341 had been infected from 1977 to 1980; 49% (167) of these men had died of AIDS, 10% (34) were alive with AIDS, 19% (65) had AIDS related complex, 3% (10) had asymptomatic generalised lymphadenopathy, and 19% (34) had no clinical signs or symptoms of HIV-I infection. Cumulative risk of AIDS by duration of HIV-I infection was analysed for all 489 men by the Kaplan-Meier method. Of these 489 men, 226 (46%) had been diagnosed as having AIDS. We estimated that 13% of cohort members will have developed AIDS within five years of seroconversion, 51% within 10 years, and 54% within 11.1 years. CONCLUSION--Our analysis confirming the importance of duration of infection to clinical state and the high risk of AIDS after infection underscores the importance of continuing efforts both to prevent transmission of HIV-I and to develop further treatments to slow or stall the progression of HIV-I infection to AIDS.

Sexual behavior before AIDS: the hepatitis B studies of homosexual and bisexual men.

Data on sexual practices, collected during studies of hepatitis B virus (HBV) infection in 1978 and 1979, were analyzed for 4910 homosexual and bisexual men from Chicago, Denver, Los Angeles, San Francisco, and St Louis. Data on sexual practices in 1978 showed that white participants had larger numbers of non-steady male sexual partners and engaged in oral-genital activities more frequently but were equally likely to engage in anal intercourse as black and Hispanic participants. San Francisco participants had more non-steady sex partners and were more likely to engage in receptive anal intercourse with non-steady partners than participants from all other sites. Analysis of data on 606 HBV-antibody-negative men interviewed on three occasions in 1978 and 1979 showed no changes in risk indices for insertive and receptive anal intercourse between these years, except in San Francisco where significant declines occurred in insertive anal intercourse and receptive anal intercourse without ejacultion in a small, highly select group of participants.

Kaposi's sarcoma in a cohort of homosexual and bisexual men. Epidemiology and analysis for cofactors.

Acquired immunodeficiency syndrome (AIDS) surveillance data for both the United States and San Francisco indicate that Kaposi's sarcoma is more common in homosexual and bisexual men with AIDS than in other adults with AIDS, and that the proportion of newly diagnosed AIDS cases presenting with Kaposi's sarcoma has been significantly declining over time. The changing epidemiology of Kaposi's sarcoma was analyzed in a well-characterized cohort of homosexual and bisexual men; laboratory and interview data from a sample of these men were evaluated for determinants of and cofactors associated with Kaposi's sarcoma. Among 1,341 men with AIDS, the proportion presenting with Kaposi's sarcoma declined from 79% in 1981 to 25% in 1989. Compared with other men with AIDS, men with Kaposi's sarcoma had a shorter interval from human immunodeficiency virus (HIV) seroconversion to AIDS diagnosis (median, 77 vs. 86 months). Men with and without Kaposi's sarcoma did not significantly differ with respect to number of sexual partners, history of certain sexually transmitted or enteric diseases, use of certain recreational drugs (including nitrite inhalants), or participation in certain specific sexual practices. The decline in Kaposi's sarcoma may at least partly be due to a shorter latency period from infection to disease. Although cofactors for the development of Kaposi's sarcoma may exist, many previously hypothesized agents were not supported by this analysis.