Maureen Miller

Transitions to injecting drug use among noninjecting heroin users: social network influence and individual susceptibility.

Objectives: To determine the incidence/predictors of transitions to injecting among noninjecting heroin users (NIUs). Methods: Street-recruited NIUs in New York City, March/1996-March/2003, were interviewed for a prospective cohort study about social network influence (communication promoting injecting; exposure to injectors) and individual susceptibility. A transition to injecting was the first drug injection following baseline. Hazards ratios (HRs) (P < 0.05) were estimated by Cox proportional hazards regression, stratified by baseline injecting history. Results: Of 369 (64% of 579) followed, former-injectors were more likely to transition to injecting (33% or 53/160 vs. 12% or 25/209; 16.0/100 person-years-at-risk [pyar] vs. 4.6/100 pyar; HR = 3.25). Independent predictors among never-injectors included using ≥2 bags of heroin daily (HR = 7.0); social network influence (communication) and homelessness (HR = 6.3); shorter-term heroin use (HR = 5.3); social network influence (exposure) and physically abused (HR = 4.7); friends approve/condone drug injecting (HR = 3.5); lower perceived social distance from injectors (HR = 2.9); and younger age at first heroin use (HR = 1.2). Independent predictors among former-injectors were social network influence (communication) and lower perceived social distance from injectors (HR = 3.4); white race/ethnicity (HR = 2.0); not very afraid of needles (HR = 1.8); and younger age (HR = 1.1). Conclusions: The risk of initiating injecting was lower than the risk of resuming injecting. Social network influence facilitates transitioning to injecting among those susceptible. Interventions to prevent injecting should address both social network influence and individual susceptibility.

Networks, resources and risk among women who use drugs

The public health tradition of intervening at the environmental level has not been fully exploited in terms of HIV prevention efforts among drug users. Women who use drugs are at particularly high risk of acquiring HIV and other blood borne and sexually transmitted infections, such as hepatitis B (HBV) and hepatitis C (HCV), and could potentially benefit from environmental level interventions. In a review of the existing literature, we examine the extent to which the linkages among multiple causal levels may contribute to the disease transmission risk experienced by women who use drugs. The multiple causal levels of risk potentially involved in the transmission dynamics of infectious pathogens include biological, behavioral, dyadic relationship, network, and structural levels. Biological and behavioral risk factors have already been examined in depth; yet, little empirical research currently exists for other causal levels. Increasingly, investigators suggest that the character and dynamics of relationships with sex partners may be an important determinant of risk, both for engaging in risk behaviors and for doing so with high-risk partners. The influence of higher-order causal level factors, specifically network and structural factors, are the least well documented, but are posited to be a principal underlying cause of the current differential HIV incidence rates between men and women who use drugs. Future research should focus on these higher-order causal levels, in order to better understand disease transmission dynamics; to better evaluate the limitations, as well as the opportunities, of current intervention efforts; to develop interventions that improve and supplement current HIV prevention efforts among women who use drugs; and to inform public policy debate.

Risk correlates of prevalent HIV, hepatitis B virus, and hepatitis C virus infections among noninjecting heroin users.

OBJECTIVE To examine lifetime correlates of HIV and hepatitis B and C (HBV and HCV) infections among noninjecting heroin users (NIUs). METHODS Between March 1996 and March 2001, 483 eligible NIUs were tested for HIV, HBV, and HCV antibodies and administered structured interviews. Multivariate logistic regression analyses were stratified by injecting history. RESULTS Among never-injectors (69.8%), significant (p <.05) correlates were unprotected sex with men who have sex with men (HIV and HBV), unprotected sex with NIUs (HIV), self-reported syphilis infection (HBV), longer duration of heroin use (HBV and HCV), shorter duration of cocaine use (HIV), blood transfusion before 1986 (HIV), and having been tattooed (HCV). Among former injectors (30.2%), significant correlates were receptive syringe sharing (HIV and HBV), frequent lifetime injection (HCV), longer duration of sexual activity (HBV), and having been tattooed (HCV). CONCLUSION Never-injectors infected with HIV and HBV appear to have become infected mainly through sexual transmission, whereas former injectors appear to have become infected with HIV and HCV mainly though injecting risk and with HBV through both injecting and sexual risk. Interventions targeted at NIUs should prevent unsafe sex as well as the initiation or resumption of injecting. In addition, unhygienic tattooing, which may lead to HCV exposure, should be a focus of prevention efforts.

The Clonality of Staphylococcus aureus Nasal Carriage

Nasal carriage of Staphylococcus aureus is often a prelude to infection with the same strain. The prevailing assumption has been that colonized individuals carry a single strain. The present study investigated the frequency of simultaneous nasal carriage of multiple strains of S. aureus. Three bacterial colonies from plated samples from colonized subjects were initially compared by pulsed-field gel electrophoresis. Fourteen of 148 S. aureus-positive samples demonstrated at least a difference of a single band; 7 of these 14 samples contained different strains, and 3 of these 7 also belonged to different accessory gene regulator (agr) types. The remaining 7 samples contained clonally related isolates; 3 of these 7 contained pairs that differed by the presence or absence of the staphylococcal chromosomal cassette mec type IV. A mathematical model that we developed predicted that approximately 6.6% of S. aureus-colonized individuals carry >1 strain. The present study demonstrates that carriage of discordant S. aureus strains in individuals with nasal colonization occurs regularly and suggests that the nares are likely sites for horizontal genetic exchange among strains.

Sexual diversity among black men who have sex with men in an inner-city community.

Dramatic increases in HIV-incidence rates have been documented for Black men who have sex with men (MSM). Moreover, MSM has become a more visible HIV-transmission route in the Black community, in part due to public interest in the “down low” (i.e., “straight” men who also have sex with men). Interviews were conducted with 21 Black MSM in central Brooklyn, New York City, in efforts to understand the diversity of MSM experience in a low income, high HIV-prevalence community. Two thirds of the men identified as either heterosexual (43%) or bisexual (24%) and 15 (71%) MSM reported recent sex with women. Conformity to masculine social role expectations made it difficult to identify sex partners in the community; therefore, men relied on private sex clubs and the Internet. The findings suggest that stigma surrounding both HIV and homosexuality may effectively insure that nonheterosexual preferences and practices remain hidden in the Black community. A focus on sexual orientation and bisexuality has obscured the issue of race in the HIV/AIDS epidemic among Black MSM. In the long term, public health promotion and HIV prevention will require greater tolerance and acceptance of sexual diversity in the Black community.

The Environment as an Unrecognized Reservoir for Community-Associated Methicillin Resistant Staphylococcus aureus USA300: A Case-Control Study

Background Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are spreading, but the source of infections in non-epidemic settings remains poorly defined. Methods We carried out a community-based, case-control study investigating socio-demographic risk factors and infectious reservoirs associated with MRSA infections. Case patients presented with CA-MRSA infections to a New York hospital. Age-matched controls without infections were randomly selected from the hospitals Dental Clinic patient population. During a home visit, case and control subjects completed a questionnaire, nasal swabs were collected from index respondents and household members and standardized environmental surfaces were swabbed. Genotyping was performed on S. aureus isolates. Results We enrolled 95 case and 95 control subjects. Cases more frequently reported diabetes mellitus and a higher number of skin infections among household members. Among case households, 53 (56%) were environmentally contaminated with S. aureus, compared to 36 (38%) control households (p = .02). MRSA was detected on fomites in 30 (32%) case households and 5 (5%; p<.001) control households. More case patients, 20 (21%) were nasally colonized with MRSA than were control indexes, 2 (2%; p<.001). In a subgroup analysis, the clinical isolate (predominantly USA300), was more commonly detected on environmental surfaces in case households with recurrent MRSA infections (16/36, 44%) than those without (14/58, 24%, p = .04). Conclusions The higher frequency of environmental contamination of case households with S. aureus in general and MRSA in particular implicates this as a potential reservoir for recolonization and increased risk of infection. Environmental colonization may contribute to the community spread of epidemic strains such as USA300.

Staphylococcus aureus ST398, New York City and Dominican Republic

Closely related Staphylococcus aureus strains of ST398, an animal-associated strain, were identified in samples collected from humans in northern Manhattan, New York, NY, USA, and in the Dominican Republic. A large population in northern Manhattan has close ties to the Dominican Republic, suggesting international transmission.

Differences between Staphylococcus aureus Isolates from Medical and Nonmedical Hospital Personnel

ABSTRACT It is unclear whether the levels of Staphylococcus aureus colonization of hospital personnel with patient exposure are increased or whether personnel become colonized with more antibiotic-resistant strains. Differences in nasal and hand carriage of S. aureus between medical and nonmedical hospital personnel were examined. No differences in nasal carriage between the two groups were found; however, there was a trend that suggested differences in the rates of hand carriage of S. aureus (18% of nonmedical personnel and 10% of medical personnel). Medical personnel were colonized with more antibiotic-resistant isolates than nonmedical personnel (mean, 2.8 versus 2.1 isolates [P < 0.03]), and the strain profiles indicated that they tended to be more clonal in origin, suggesting that exposure to hospital isolates alters the colonization profile.

Factors Associated with the Prevalence and Incidence of Trichomonas vaginalis Infection among African American Women in New York City Who Use Drugs

BACKGROUND Trichomoniasis vaginalis, the most prevalent nonviral sexually transmitted infection, is associated with negative reproductive outcomes and increased HIV transmission and may be overrepresented among African Americans. METHODS A total of 135 African American women who used drugs were screened for Trichomonas vaginalis on > or =2 occasions between March 2003 and August 2005. Women were administered a structured questionnaire in a community-based research center, underwent serological testing for human immunodeficiency virus and herpes simplex virus type 2, and were screened for Neisseria gonorrhoeae and Chlamydia trachomatis. RESULTS Fifty-one women (38%) screened positive for T. vaginalis at baseline. Twenty-nine (31%) of 95 women with negative results of baseline tests became infected, for an incidence of 35.1 cases per 100 person-years at risk (95% confidence interval [CI], 23.5-49.0). Prevalent infection was associated with drug use in the past 30 days, and incident infection was associated with sexual behavior in the past 30 days, namely having >1 male sex partner. Women who reported having >1 partner were 4 times as likely as women with fewer partners to acquire T. vaginalis (hazard ratio, 4.3; 95% CI, 2.0-9.4). CONCLUSION T. vaginalis may be endemic in this community of African American women. A control strategy that includes T. vaginalis screening in nonclinical settings and rapid point-of-care testing could contribute to the disruption of transmission of this pathogen.

Sexual and Other Noninjection Risks for HBV and HCV Seroconversions among Noninjecting Heroin Users

BACKGROUND Many heroin users do not inject drugs but may still be at risk of infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV), via sexual or other noninjection-related activity. METHODS Noninjecting heroin users (NIUs) in New York City who were recruited and prospectively followed during March 1996-February 2003 were tested for anti-HIV, anti-hepatitis B core antigen, and anti-HCV and were interviewed about their sexual and other noninjecting risk. A seroconversion is represented by the first positive test result after the last negative test result. Hazard ratios (HRs) (P<.05) were estimated by use of Cox proportional hazards regression. RESULTS Of 253 HIV-negative participants, 2 seroconverted (0.29/100 person-years at risk [pyar]); of 184 HBV-negative participants, 16 (3.3/100 pyar); and, of 219 HCV-negative participants, 16 (2.7/100 pyar). Independent predictors of seroconversion were, for HBV, being a female who engages in unprotected receptive anal sex (HR, 6.8), having short-term sex partners (HR, 6.2), and being a male with male sex partners (HR, 5.7); for HCV, being a male who receives money/drugs for sex (HR, 5.6) and sharing noninjecting crack-use equipment (HR, 4.5). CONCLUSIONS NIUs are at considerable risk of HBV infection via high-risk sex; and, for HCV, via high-risk sexual activity and the sharing of noninjecting crack-use equipment. Interventions in NIUs must seek to reduce high-risk sexual activity and the sharing of noninjecting drug-use equipment.