Determinants of HIV seroprevalence rates among sites participating in a community-based study of drug users

Migration and transmission of blood-borne infections among injection drug users: understanding the epidemiologic bridge

Migration is one of many social factors contributing to the spread of HIV and other blood-borne or sexually transmitted infections (STI). Bringing together large numbers of people from diverse settings, the process of migration moves infected individuals to diverse geographic locations. Injection drug users (IDU) are a relatively mobile group, often moving between cities, smaller communities, and across international borders for reasons of work, security, or access to narcotics. This mobility indicates the potential for IDU who engage in risky behavior outside their home areas to transmit HIV infection to other IDU, their sex partners, and others in the population. The objectives of this review are to examine: (1) the influence of drug trafficking and the spread of drug use on the diffusion of HIV, (2) the influence of migration on drug use and HIV-related risk behaviors among migrants, and (3) the mobility patterns of IDU and its role in the spread of HIV. We also discuss the potential policy implications of addressing prevention and care issues in mobile drug using populations.

Injection drug use and crack cocaine smoking: independent and dual risk behaviors for HIV infection

PURPOSE

Previous studies have examined the practices of injecting drugs or smoking crack cocaine as high-risk, but independent, factors for HIV transmission. To explore the independent and dual risks of injection practices and crack smoking, this study examined HIV seroprevalence rates among distinct drug user groups, based on patterns of daily administration.

METHODS

A sample of 3,555 drug users and neighborhood controls in urban Miami, FL and rural Belle Glade and Immokalee, FL were partitioned into four mutually-exclusive groups: 1) injection drug users (IDUs); 2) crack-cocaine smokers; 3) dual users who both smoked crack and injected drugs; and 4) non-drug-user controls.

RESULTS

HIV seroprevalence rates were 45.1% for IDUs, 30.5% for dual users, 20.1% for crack smokers and 7.3% for controls. Multivariate logistic regression analysis found that when compared with controls odds ratios for HIV seropositivity were 9.81 for IDUs, 5.27 for dual users, and 2.24 for crack smokers.

CONCLUSIONS

These findings provide evidence of: 1) behavioral and structural co-factors that influence HIV exposure patterns among drug users; and 2) the substantially higher risk of HIV infection among IDUs compared with other drug users. Intervention strategies must be tailored for the specific drug use subpopulations to optimize efficacy.

Explaining the geographical variation of HIV among injection drug users in the United States

Distinct physical and chemical types of street heroin exist worldwide, but their impact on behavior and disease acquisition is not well understood or documented. This article presents a hypothesis to explain the unequal diffusion of HIV among injection drug users in the United States by examining the distribution and use of one type of heroin--"Mexican black tar." Drawing on ethnographic, clinical, epidemiological, and laboratory data, we suggest that the chemical properties of black tar heroin promote the following safer injection practices: (1) the rinsing of syringes with water to prevent clogging; (2) the heating of cookers to promote dissolution; and (3) a rapid transition from venous injection to subcutaneous or intramuscular injections.

Mechanisms of cocaine-induced decreases in immune cell function

Cocaine has previously been shown to decrease mitogen-induced T lymphocyte proliferation in rats following intravenous administration. However, in this report, it is demonstrated that central administration of cocaine (1-50 microg) had no effect on lymphocyte proliferation responses. Similarly, the quaternary derivative, cocaine methiodide, also suppressed lymphocyte proliferation only when administered peripherally (6.5 mg/kg), and not centrally (1-20 microg). These results suggest that the effects of cocaine were mediated through a peripheral mechanism. Since significant elevations in plasma corticosterone were observed with all routes of administration of cocaine, the effects of cocaine did not appear to be due entirely to activation of the HPA axis. Instead, the peripheral administration of the local anesthetic, lidocaine (5 mg/kg) or the monoamine reuptake inhibitor, RTI-55 (2-5 mg/kg), produced significant suppressive effects on proliferation. suggesting that both of these peripheral activities of cocaine may be involved in the alteration of lymphocyte responses.

Between-city variation in frequency of injection among Puerto Rican injection drug users: East Harlem, New York, and Bayamon, Puerto Rico

Frequency of injection has been consistently found to be higher among Puerto Rican Injection drug users (IDUs) than among other groups of IDUs. Several explanations have been suggested, but an empirical explanation has yet to be presented. This study compares the frequency of injection of Puerto Rican IDUs in East Harlem, New York, with that of IDUs in Bayamon, Puerto Rico. Study subjects comprised 521 Puerto Rican IDUs from East Harlem and 303 IDUs from Bayamon. The mean frequency of injection among IDUs in East Harlem was 2.8, the corresponding mean in Bayamon was 5.4. Younger IDUs reported a higher number of daily injection episodes than older IDUs, and the IDU group in Bayamon was 5 years younger than the group in East Harlem. The drug use variables accounted for a greater portion of the between-city difference than the demographic and psychosocial variables. Use of noninjected drugs, as well as the use of prescribed methadone, were found to be associated with a lower number of daily injections. Conversely, injection of cocaine, injection of cocaine mixed with heroin ("speedball"), and injection of larger amounts of drug solution were found to be associated with a higher number of daily injections.

Prevalence and incidence of HIV among out-of-treatment injecting drug users, Chicago 1994-1996

OBJECTIVES

To assess HIV prevalence, incidence, and associated risk factors among IDUs in Chicago.

METHODS

Seven hundred ninety-four street-recruited IDUs ranging in age from 18 to 50 years, who were not in drug treatment at study enrollment, were interviewed and tested for HIV at baseline and at two follow-ups scheduled 6 and 12 months after baseline. Questionnaires assessed respondents' demographic characteristics, medical and drug treatment histories, drug use, and sexual practices.

RESULTS

HIV seroprevalence at baseline was 18%. Logistic regression identified the following determinants of prevalent HIV infection: Puerto Rican ethnicity, homosexual or bisexual self-identification, injecting for 4 or more years, and having smoked crack cocaine in the past 6 months. Follow-up data were collected from 584 (73.6%) participants. Mean duration of follow-up was 16.5 months, indicating that most subjects had follow-up intervals longer than the scheduled 6 and 12 months. Seven HIV seroconversions were observed in 632 person years of risk, yielding an incidence rate of 1.1 per 100 person years of risk. Injection for 3 or less years was positively associated with HIV seroconversion.

CONCLUSIONS

The findings provide evidence of a decline in HIV incidence among IDUs, though newer injectors remain at elevated risk for infection.

Estimated HIV risk among Hispanics in a national sample of drug users

OBJECTIVE

To estimate and compare the HIV risks among three Hispanic subpopulations.

METHODS

Chronic drug users participating in a nationwide intervention study on drug use were interviewed with regard to drug use and sexual behavior. HIV risk was estimated using information about individuals' HIV-relevant behaviors, the social context (i.e., city) in which such behaviors occur, and published estimates of HIV transmission for various risk behaviors. Multiple linear regression analysis was used to investigate differences in estimated HIV risk between Puerto Rican, Mexican-American, and Mexican drug users, accounting for sociodemographic factors, sexual preference, and geographic region.

RESULTS

Puerto Ricans had significantly greater estimated overall HIV risk, estimated injection risk, and in general, significantly greater estimated sexual risk than Mexican Americans and Mexicans. No significant differences were found in any estimated risk between Mexican Americans and Mexicans in this sample. No significant differences were found among any of the subgroups for estimated risk from having anal sex while using a condom, or from having receptive anal sex without using a condom.

CONCLUSIONS

These findings suggest that Puerto Ricans who use drugs experience a higher risk of HIV infection than other Hispanic drug users. Research is needed to identify which economic, social, and cultural components account for this increased risk.

Usuários de drogas injetáveis e infecção pelo Vírus da Imunodeficiência Humana: epidemiologia e perspectivas de intervenção

Dos cerca de 130 mil casos de aids notificados no Brasil entre 1980 e fevereiro de 1998, 21% estão diretamente relacionados ao uso de drogas injetáveis. Este artigo revisa aspectos da epidemiologia da infecção pelo HIV e outros patógenos de transmissão sangüínea, entre usuários de drogas injetáveis (UDI), visando a subsidiar as pesquisas e a implementação de propostas de intervenção em nosso meio. A população de UDI é heterogênea e, ao contrário do estereótipo, nem todos os UDI provêm de minorias masculinas das grandes áreas urbanas. Esta população está em contínua transformação, com mudanças marcantes ao longo do tempo na sua composição, hábitos e padrões de consumo. A estimativa precisa do número de UDI em uma dada localidade constitui tarefa difícil, embora disponha-se de novas metodologias, como o método de captura-recaptura. A combinação de dados provenientes de diversas fontes se mostra também indispensável. Estudos no sentido de monitorizar os padrões e tendências do uso de drogas injetáveis, segundo diferentes níveis de agregação e em intervalos regulares, permitem estimar prováveis aumentos ou decréscimos desta população e detectar mudanças relevantes nos seus comportamentos, contribuindo para orientar as estratégias de intervenção e alocação ótima de recursos. Evidências recentes demonstram que, devido à exposição parenteral e sexual aos diferentes patógenos, as infecções nesta população ocorrem precocemente, demandando intervenções prontas e abrangentes quanto aos UDI em atividade, e esforços no sentido de minimizar a transição para a via injetável e oferecimento de alternativas de tratamento clínico e para o abuso de drogas.