Lower Broadly Neutralizing Antibody Responses in Female Versus Male HIV-1 Infected Injecting Drug Users

Understanding the factors involved in the development of broadly neutralizing antibody (bNAb) responses in natural infection can guide vaccine design aimed at eliciting protective bNAb responses. Most of the studies to identify and study the development of bNAb responses have been performed in individuals who had become infected via homo- or heterosexual HIV-1 transmission; however, the prevalence and characteristics of bNAb responses in injecting drug users (IDUs) have been underrepresented. We retrospectively studied the prevalence of bNAb responses in HIV-1 infected individuals in the Amsterdam Cohort, including 50 male and 35 female participants who reported injecting drug use as the only risk factor. Our study revealed a significantly lower prevalence of bNAb responses in females compared to males. Gender, transmission route and CD4+ count at set point, but not viral load, were independently associated with the development of bNAb responses in IDUs. To further explore the influences of gender in the setting of IDU, we also looked into the Swiss 4.5k Screen. There we observed lower bNAb responses in female IDUs as well. These results reveal that the emergence of bNAbs may be dependent on multiple factors, including gender. Therefore, the effect of gender on the development of bNAb responses is a factor that should be taken into account when designing vaccine efficacy trials.

Characteristics of male and female injecting drug users of the AjUDE-Brasil II Project

The object of this study is to compare female and male injection drug users (IDUs) in terms of sociodemographic profile and aspects of their initiation to the use of injection drugs. It was a cross-sectional and multicentric study realized in 2000-2001 in six Brazilian syringe-exchange programs. 146 women and 709 men were interviewed, with average ages of 29.5 and 28.3 years, respectively. Both began injection drug use at similar ages, 18.6 and 19.3, for women and men, respectively, although women report more frequently than men that they were initiated by a sexual partner to acquiring drugs and syringes, and to the act of injection. Compared to men, women report significantly more regular sexual partners (83% versus 72%); fewer casual partners (39% versus 58%), more use of injection drugs with their partners, as well as more "exchange" of sex for drugs. Among HIV-seropositive individuals, women show less education, had more chance of their sexual partners participating in their initiation to injection drugs, and report sexual partners that used injection drugs more frequently. Female IDUs exhibit aspects of behavior indicating greater vulnerability to HIV infection than do males.

Targeted mass treatment for syphilis with oral azithromycin in Vancouver, Canada

A recent paper by Rekart and colleagues (1) presented the findings of a mass treatment intervention to eliminate an outbreak of syphilis in Vancouver, British Columbia. Following several years of very low reported infectious syphilis rates in British Columbia (less than 0.5 per 100 000 population (2), with the majority of cases acquired overseas, there was a marked increase in numbers of reported cases from mid-1997 onwards. This was largely due to a geographically localised outbreak in Vancouver’s disadvantaged downtown eastside area, with rates reaching 126 per 100 000 in this area in 1999. Sixty five percent of the 277 cases reported were among persons who had contact with a potential source of their infection in or from this area. The outbreak was spread mainly through heterosexual contact, with 42% of patients associated with the sex industry (18% sex workers and 24% clients, (2)). Only 6% of cases were in men who have sex with men (MSM). Given high HIV rates among among injection drug users (IDUs) in Vancouver, and the frequent involvement of female IDUs involved in sex work, rising syphilis incidence could facilitate the spread of HIV infection both within the disadvantaged population of Vancouver’s downtown eastside itself, as well as outwards from sex workers through clients into the general population (2).

Prevalence of antibodies to hepatitis C virus, HIV and human T-cell leukaemia/lymphoma viruses in injecting drug users in Tayside, Scotland, 1993–7

The prevalence of blood-borne viruses in injecting drug users (IDUs) in Tayside, Scotland was determined by testing serum samples from IDUs who underwent attributable HIV antibody testing during 1993–7. The prevalence of antibodies to HIV was 29/802, (3·6%); to hepatitis C virus (HCV) 451/691, (65·3%); and to human T-cell leukaemia/lymphoma viruses type 1 and 2 (HTLV) 0/679, (0·0%). The prevalence of HIV and HCV antibodies were higher in subjects over the age of 25 (P=0·03 and P=0·001, respectively). During 1993–7 the prevalence of HCV fell only in younger female IDUs (P<0·01). HIV prevalence has declined dramatically since 1985, when a rate of 40% was recorded in similar populations. Harm reduction measures have failed to control HCV the spread of infection among IDUs in Tayside, as indicated by the high proportion of antibody positive IDUs, particularly males under the age of 25. Future studies should address the nature and effective reduction of continuing risk taking among IDUs in Tayside.

Syphilis in injecting drug users: clues for high-risk sexual behaviour in female IDUs

The objective was to measure the gender-specific differences for syphilis and for the sexual transmission of human immunodeficiency virus (HIV) in a crosssectional analysis of injecting drug users (IDUs) admitted to detoxification between February 1987 and January 1990. HIV was determined by enzyme-linked immunosorbent assay (ELISA) and confirmed with Western blot. For syphilis reactive samples to a rapid plasma reagent (RPR) were confirmed with treponemal tests (FTA-ABS or MHA-TP). Of the 386 heterosexual IDUs, 68% were HIV-positive and 4.7% had serologic syphilis (RPR and FTA-ABS or MHA-TP positive). Syphilis was higher in women (12%) than in men (3%), and women reported a significantly (P< 0.001) higher number of sex partners. Men had an IDU as a sex partner more often than women did (P=0.001). Serologic syphilis in women was associated with having had more than one sexual partner in the previous year (P=0.028) but this association was not present in men. HIV infection was not associated with syphilis in male IDUs. However, HIV was present in all women with syphilis that reported more than one partner.