Reducing risk of sexually transmitted infections and HIV in male and female sex workers

Use of male and female sex workers is common throughout the world. Sex workers may be referred to as prostitutes, commercial sex workers, lap dancers, escorts etc but trade of sexual activity for money, food or drugs is the common factor.

A common assumption is that because of the frequency and number of change of sexual partners with commercial sex workers that they will be more exposed to sexually transmitted diseases and HIV and thus more likely to acquire, carry and spread STD/STI’s and HIV. As a clinician working in a clinic where I see many people, male and female, who have used sex workers, the concept of risk is one that generally occurs after the sexual event.

There is good evidence that male and female sex workers and their clients may represent a significant source of new HIV and other sexually transmitted infections. Condoms are very, very effective in reducing spread of STD’s and HIV but often they are not used for penetrative vaginal and or anal sex.

Many STD’s/ STI’s are easily treatable using modern antibiotic therapies. Ease of treatment however may miss the point. We know that gonorrhoea and also Chlamydia will increase the amount of HIV virus which is shed from both the cervix and also in semen of HIV infected men and women. Equally, concurrent infection with herpes 2 virus in the genital tract of either of the individuals will make HIV acquisition much more likely for a previously HIV negative partner.

Gonorrhoea, syphilis, chlamydia and herpes in the previously HIV negative individual engaging in unprotected penetrative sex with an HIV positive individual will markedly increase the chances of new HIV infection. These newly infected HIV positive individuals pose an exceptionally high risk of infecting other sexual partners because they are often unaware of the risks they have taken and unaware of the new HIV infection gaining rapid momentum in their body. New HIV infection will take a few weeks to generate often several million copies of HIV virus per ml of blood or semen making these individuals extremely infectious in the initial phase.

When contemplating exceptionally high background rates of STD and HIV in populations there is a correct tendency to view this as a feature of poverty and also developing societies such as Sub Saharan Africa etc. South Africa has the highest rate of HIV in the world. But there is a catch and that is that in different population pockets around the world, such as Washington DC in the USA, HIV infection rates in some sub-groups exceeds that of the South African HIV rate. Consequently, interventions to reduce the spread of HIV need to be universally applied and the notion that the highest rates are in the poorest countries is part of the picture.

Vickerman etc al, writing in the journal Sexually Transmitted Infections (2010:86:163-168) used mathematical modeling to estimate the impact of periodic presumptive treatment on the transmission of sexually transmitted infections and HIV amongst female sex workers. The female sex workers were of a group taken from Johannesburg.

The article started with the premise that periodic treatment of common STD’s / STI’s using antibiotics without pre-testing could reduce the rates of genital ulcer disease, gonorrhoea, Chlamydia. What was not known was whether reduction of these infections by interval treatments would also consequently reduce the rate of HIV transfer.

The conclusion reached was that whilst possibly optimistic assumptions had been made about the impact of blanket antibiotic use in high risk female sex worker populations in reducing onward HIV transmission, there was reason to believe that antibiotic interventions with good population coverage could noticeably reduce the HIV infection rate amongst female sex workers with previously inadequate STI and STD treatments.

Clearly the use of antibiotics themselves would only impact on the bacterial diseases and have no impact on HIV itself – but, because the bacterial diseases enhance the shedding and availability of HIV in cervical fluid and semen, reduction in bacterial contamination will reduce spread of HIV. This is not a substitute for condom use but as the accompanying Editorial points out, many vulnerable sex workers are often not in a position to enforce condom use.

A further weapon in the identification of early HIV before onward HIV transmission is the use of very early HIV testing methods. Confusion has reigned over the appropriate testing intervals and this has largely occurred because different and more sensitive HIV testing methods have become available over the last 30 years. The confusion has been compounded a little by the advice of government regulatory bodies in different countries who have tailored their advice to what they now about commonly used HIV testing methods on the ground.

In the UK 4th generation HIV testing methods using HIV 1 and 2 antibodies and also p24 antigen ( a core HIV viral protein) have been commonplace for many years and good experience has been gained with these tests.

A further advance has been the development for diagnostic purposes of an HIV 1 and 2 RNA PCR test which will identify extremely early HIV infection often before symptoms of Acute Retroviral Syndrome have appeared. This test can be performed from seven days post possible HIV exposure. The importance of such an early test is that it firstly enables early intervention in terms of medications if desired and secondly it allows for the opportunity to avoid infecting others.

Simultaneous early PCR testing will allow for detection of a host of bacterial and viral STD’s / STI’s such as herpes 1 and 2, trichomonas, gardnerella, Chlamydia, gonorrhoea, ureaplasma, mycoplasma, and hepatitis C and B.