- Category: HIV Prevention
- Published on Thursday, 07 August 2014 00:00
- Written by Mara Kardas-Nelson
Presentations at a session on HIV prevention strategies for sex workers, which took place at the 20th International AIDS Conference last month in Melbourne, showed that while consistent condom use is generally high among female sex workers, other barriers remain to effective prevention of HIV transmission and to care for those who are HIV positive.
[Produced in collaboration with Aidsmap]
Importantly, while condom use by female sex workers with their clients is notably high in some populations, the same women report lower rates of condom use with regular partners, pointing to a potential gap in HIV prevention strategies, potential for transmission, and potential behavioral, psychological, social, and other barriers to partner condom use. The session, entitled "Successful HIV Prevention Strategies with Female Sex Workers," included a discussion of different models which aim to help to prevent infections among sex workers and other vulnerable populations, ranging from combination prevention efforts that rely on behavior, biomedical, and structural interventions, to the use of oral pre-exposure prophylaxis (PrEP).
Central America: Combination Prevention for Women
Jorge Rivas of the Pan American Social Marketing Organization (PASMO) presented a study that considered the impact of combination prevention on HIV testing and condom use with both clients and regular partners among women who did sex work in 6 Central American countries: Guatemala, El Salvador, Nicaragua, Costa Rica, Panama, and Belize. The study, part of a combination prevention program in effect from 2010 to 2015, included 3293 female sex workers aged 18-49 years.
PASMO found that condom use with clients was already often very high, with over 80% of sex workers in most countries reporting consistent condom use with clients (Belize was the outlier, where only 60% reported consistent condom use with clients).
Condom use with regular partners, however, was significantly lower: only 30% of female sex workers in El Salvador and Guatemala, for example, reported consistent condom use with regular partners. Panama and Costa Rica had the highest percentages, but still only approximately 60% reported regular condom use with partners there.
Reported HIV testing within the last 12 months among female sex workers varied widely between countries, with only 65% having been tested in Belize compared to nearly 100% in Costa Rica.
Perhaps, Rivas suggested, because condom use with clients is already very high in all 6 countries, none of the interventions -- behavioral (such as behavior change communication activities), biomedical (such as voluntary HIV counseling and testing), or structural (such as referral to drug and alcohol treatment programs) -- either individually or in tandem, affected female sex workers' condom use with clients.
However, with regards to condom use with regular partners, behavioral interventions had a positive impact in Costa Rica and Belize (with sex workers being 2.73 times and 3.8 times more likely to use condoms, respectively), behavioral and biomedical interventions together had a positive impact in Costa Rica and Panama (3.54 and 2.35 times more likely, respectively), and biomedical, biological, and structural interventions together had a positive impact in El Salvador (2.3 times more likely). HIV testing, however, was unaffected by any of the interventions.
Pointing to the study's findings that behavioral and biomedical interventions together had a more significant impact on female sex workers' use of condoms with regular partners, as compared to just behavioral interventions, in Costa Rica, Rivas concluded that "combination prevention strategies can have a positive impact on condom use with regular partners." He added that the study relied on after-the-fact self-reporting, so may be prone to recall bias and to over- or under-reporting.
Interestingly, Belize -- which fared significantly worse in terms of condom use with clients and HIV testing in the last 12 months, but better than some other countries when considering condom use with regular partners -- is the only country of the 6 where sex work is illegal, according to Rivas.
India: PrEP in Sex Workers and Gay Men
Both female sex workers and men who have sex with men (MSM) in Bangalore, India, also report high rates of condom use with high-risk partners, ranging from 75% to 90%, but much lower rates of condom use with long-term heterosexual partners, according to a presentation given by Kate Margaret Mitchell of the London School of Hygiene and Tropical Medicine.
Mitchell presented a mathematical modeling study that considered the potential preventive impacts of oral PrEP taken by female sex workers and MSM in Bangalore for these high-risk populations and for the population as a whole.
While the impact of oral PrEP has been studied in MSM and heterosexual couples, the impact on female sex workers has not yet been extensively studied, although several projects are planned or currently underway. Mitchell's study was done in preparation for 2 planned demonstration programs in Kolkata and Mysore. As of 2009, 8% of Bangalore's female sex workers and 16.5% of the city's MSM were HIV positive.
The model considered behavioral data (such as number of partners and frequency of condom use) from surveys and biological data (such as likelihood of HIV transmission per sex act) from literature, and considered an estimated 12,000 female sex workers and 18,000 MSM who were already in contact with HIV or other services, and therefore likely to be able to access PrEP.
Estimating a 40% coverage rate and 60% efficacy (which considers both efficacy of oral PrEP and adherence), Mitchell and her co-authors found that 23% of HIV infections among female sex workers could be averted within a decade if oral PrEP was offered to this population, with an overall 3.4% reduction in HIV infections in the general population. The impact from offering the intervention to MSM was markedly lower, but offering oral PrEP to both female sex workers and MSM could result in a population-wide 6% decrease in HIV infections within 10 years.
Mitchell emphasized that the population-specific and population-wide impact significantly increased over time, with many more lives saved for far less resources over 20 years as compared to 10. As such, she suggested that policy-makers and program planners consider longer-term outcomes when looking at both cost and efficacy of providing PrEP to these high-risk populations.
Zimbabwe: HIV Testing and ART Access for Sex Workers
Frances Cowan of the SAPPH-IRe program in Zimbabwe also reported high estimates of condom use among female sex workers and their clients, with 60% reporting regular condom use. SAPPH-IRe stands for Sisters Antiretroviral therapy Program for Prevention of HIV -- an Integrated Response, a collaborative project between the Zimbabwe Ministry of Health and international partners.
Cowan's presentation offered results from a baseline survey conducted at the start of an 18-month study that will consider the impact and cost of additional interventions, such as PrEP and on-site antiretroviral therapy (ART), on HIV prevention among female sex workers, as compared to the usual package of services currently offered by SAPPHI-IRe, such as health education and HIV counseling and testing.
From November 13 to December 20, 2013, a total of 2722 female sex workers took part in the survey. The mean age was 32 years (range 18-65 years), and the majority had started sex work sometime between age 20 and 24 (although 18% started before the age of 18). Self-reported instances of intimate partner violence was high, at 34.7%, with 28.3% from clients. 4.3% of female sex workers reported that they had been raped during the last 12 months.
Despite high rates of self-reported condom use with clients, HIV prevalence among the population was very high, at 56%. Only 61% of those who were HIV positive reported that they knew their status. 40% of HIV positive female sex workers said they were taking ART, with 31% of these having undetectable viral load. Cowan noted potential reporting bias, given that 14% of HIV positive antiretroviral therapy had an undetectable viral load, despite saying they were not on ART.
The outcomes of this study show that while access to services for female sex workers is increasing in Zimbabwe -- 2011 research noted that only 25%-35% of sex workers were on ART as compared to SAPPH-Ire’s 40% -- it is still inadequate, particularly with regards to HIV testing and diagnosis.
J Rivas, S Lungo, S Ruether, et al. Are combination prevention interventions effective? The impact of combination prevention on increasing condom use among female sex workers in Central America. 20th International AIDS Conference. Melbourne, July 20-25 2014. Abstract ThAC0302.
KM Mitchell, F Terris-Prestholt, HJ Prudden, et al. Estimating the potential impact and efficiency of pre-exposure prophylaxis for female sex workers and men who have sex with men in Bangalore, southern India. 20th International AIDS Conference. Melbourne, July 20-25 2014. Abstract ThAC0303.
F Cowan, C Davey, S Napierala Mavedzenge, et al. Estimation of the HIV care cascade for female sex workers in Zimbabwe: baseline results of the SAPPH-Ire trial. 20th International AIDS Conference. Melbourne, July 20-25 2014. Abstract ThAC0305LB.