HIV-1 infection among female commercial sex workers in rural Thailand

Abstract

An explosive epidemic of HIV-1 occurred among sex workers in a semi-rural area of northern Thailand from 1989. These HIV-1 incidence estimates, which are among the highest rates of sexual transmission ever reported, highlight the extreme vulnerability of female sex workers to HIV infection, even in a non-urban setting.

How much do blood exposures contribute to HIV prevalence in female sex workers in sub-Saharan Africa, Thailand and India?

“…27,67 In contrast to low to moderate levels of HIV prevalence in FSWs in much of central Africa, an estimated 50 years after the virus began to circulate, much higher prevalence and incidence have been observed in some African and Asian countries with new epidemics (Table 4). 55 In Nairobi, Kenya, annual HIV incidence was 47% in a cohort of FSWs followed during 1985-87. 24 These high rates of HIV incidence are far greater than rates associated with vaginal or even anal exposures in developed countries, but are comparable to rates associated with parenteral exposures during IDU 77 and nosocomial outbreaks.…”

“…Country, city, years of field research Group of FSWs studied Incidence (per 100 PYs) All FSWs FSWs who worked p1 year High incidence in new epidemics Kenya, Nairobi, 1981-83 3 4-82 Kenya, Nairobi, 1985-87 24 47 Kenya, Nairobi, 1985-94 68 42 Thailand, Chiang Mai, 1988-89 69 Brothel based 0.4-44 Thailand, Chiang Mai, 1989-90 13,69 Brothel based 36-72 à Thailand, Chiang Rai, 1989-93 55 69 72 62 63 Kenya, Nairobi, 1998 73 27 38 -Thailand, Chiang Mai, 1992 60 Brothel based 40 36 Thailand, Chiang Mai, 1992 74 80% brothel based 65 47 Higher incidence or prevalence in brothel-based vs. non-brothel FSWs Thailand, Chiang Rai, 1991-96 56 Brothel based 9.3 Non-brothel 1.0 Thailand, north, 1992 60 Brothel based 40 Non-brothel 6 Thailand, south, 1992 60 Brothel based 21 Non-brothel 7 Thailand, Chiang Rai, no date 75 Brothel based 24 Non-brothel 1 Thailand, north, 1993 76 Brothel based 29 Non-brothel 4.0 PY=person years; Seaters=FSW working out of their homes; Roamers=FSW seeking clients in brothels, bars, etc à See text -0-2 years sex work…”

“…of reference49 ). For Thailand 1989-93, incidence for gonorrhoea and syphilis are calculated as 12 times the reported rate per 100 person-months for repeat testers(Table 3 of reference55 ). For Thailand 1991-96, numbers of infections are estimated from reported PYs with one or more positive tests during a follow-up period multiplied by 3.75 follow-up periods per year; incidence is calculated by assuming that infections occur at the midpoint of an average follow-up period (see page 1893 andTable 3 of reference 56 )…”

STI declines among sex workers and clients following outreach, one time presumptive treatment, and regular screening of sex workers in the Philippines

“…1 Sex workers also face extremely high risk of sexually acquired HIV infection with incidence rates as high as 17 per 100 person months. 2 Yet it is estimated that only 16% of sex workers in low and middle income countries have access to even basic HIV prevention services. 3 Sex workers, once infected, can transmit STIs and HIV to a far larger number of susceptible clients, who serve as efficient ''bridge'' groups for even wider transmission.…”

Combining community approaches and government policy to reduce HIV risk in the Dominican Republic

“…Because of multiple sexual partners, female sex workers, especially those from disadvantaged socioeconomic settings, are particularly vulnerable to HIV infection and other sexually transmitted infections (STIs) (Gysels et al 2002;Ghys et al 2001;Kalipeni 2000;Campbell 2000;Gray et al 1997;Aklilu et al 2001). Epidemiological studies from many countries have documented significantly higher rates of HIV infection among female sex workers, compared to other population groups within the same geographic area and cultural context (Asamoah-Adu et al 2001;Quan et al 2000;Mehendale et al 1995).…”