Do 50% of prostitutes have HIV?

Question

The Prostitution Statistics You Have to Know claims that:

50% of prostitutes throughout the world have contracted the HIV virus

(For this statistic it references this BBC news article: The men who sleep with prostitutes)

Is this true?

Answer 1

It may be true or true-ish among some sub-populations.

THE PROSTITUTE PARADOX from 1993 says,

• In New York City, for example, 40 to 50 percent of streetwalkers (a very low caste of prostitute) who have used IV drugs over the past decade are HIV seropositive.
• Among call girls in New York City (a higher caste of prostitute), no seropositivity was found among those who were drug free. These figures were constant between 1984 and 1989.
• The same sorts of figures have been found in all Western nations.

It says that the risk factor is the using of intravenous drugs.

Two more data points:

• List of countries by HIV/AIDS adult prevalence rate states than in a few countries (Lesotho, Botswana, and Swaziland) in Africa, the incidence is 25% in the general population of adults (it's 17% in South Africa), and I imagine it may be higher than that already-very-high average among any prostitutes there.

• Perceived transmissibility of STIs: lack of differentiation between HIV and chlamydia claims (based on Mastro TD, de Vincenzi I. Probabilities of sexual HIV-1 transmission. AIDS1996;10(Suppl A):S75–82.) that,

The estimated probability of HIV transmission from an infected heterosexual man to a woman in one act of unprotected vaginal intercourse is 0.1%

Probability of Heterosexual HIV-1 Transmission per Coital Act in Sub-Saharan Africa cites another study which says that 0.2% is a baseline: when the man is known to be HIV positive, and the rate of condom use is high (in the 78% to 93% range).

My guess is that 50% is too high to be a world average, especially in populations where HIV isn't pandemic.

However the maths says that infection rate of 0.3% implies a 50% chance of infection after 230 sex acts, when a condom is used more-or-less regularly, if all clients are HIV-positive.

If 10% of clients are HIV positive then the number is 2300 instead of 230.

Answer 2

According to this article published in the International Journal of Public Health by the Institute of Tropical Medicine, Antwerp, it's, on average significantly lower than 50%:

Source: http://link.springer.com/article/10.1007%2FBF02084300

Funnily enough, this is actually the most recent chart I could find like this. I guess no one bothered to do another study in the last 25 years. However, there are a few more articles I found that give more recent percentages for certain areas.

Nigeria's growing commercial sex industry is a major source of human immunodeficiency virus (HIV) transmission, and studies undertaken in Lagos suggest that up to 20% of female prostitutes are HIV-infected.

Source: http://www.popline.org/node/288578

But there is one more problem with the chart above, in that it only takes into account prostitutes that don't use intravenous drugs, and just assuming 0% in that field is just ludicrous.

According to one PubMed article, Human immunodeficiency virus seroprevalence and condom use among female sex workers in Italy, about 37% use intravenous drugs:

Overall, 131 of 802 (16%) were HIV positive: 36 of 558 (6%) professional sex workers and 95 of 244 (39%) sex workers who used intravenous drugs.

Source: http://www.ncbi.nlm.nih.gov/pubmed/9800254

Sadly I can't personally find one specifically for the US. But, that said, based on the information above, I would hazard a guess that it would be significantly less than 50%