According to a report in The New York Times, Dr. Francis A. Plummer has studied thousands of prostitutes here since 1981, when he was a junior researcher at the University of Manitoba. He was originally looking for chancroid, a bacterial disease producing skin ulcers, and gonorrhea, but when the human immunodeficiency virus (HIV) was discovered, he added that to his studies as well.
What Plummer discovered over that nearly 24-year period was that about five percent of the prostitutes in his study remained uninfected by HIV despite hundreds of exposures. The percentage of Kenyans infected with HIV is estimated to be just under 7 percent, or 1.4 million citizens, while other sub-Saharan countries such as Namibia, Swaziland, Botswana, Zambia and Zimbabwe report infection rates of between 18 percent and 25 percent of the population.
The apparent natural resistance of active prostitutes to HIV in such far-flung countries as Gambia and Thailand has been well-known for years, but the reason for such immunity has not.
However, according to the Times article, Plummer, who directs Canada's equivalent of the Centers for Disease Control, working with colleagues from universities across Canada as well as the University of Nairobi, has discovered that the prostitutes display protective immune responses both in their white blood cells and in their vaginal walls. Constant repeat exposures to the virus seem to boost those responses, but if the women stop working in the sex trade and later return to it, they often lose their immunity and get infected.
According to Plummer's research, resistance to HIV "clearly runs in families," and the uninfected women seem to have unusually slow immune systems, and the doctor, with a recent research grant of $8 million, plans to study the uninfected women's families and relatives, including their immune systems' reactions to other diseases as well.
All attempts so far to make an anti-HIV vaccine have failed, but Plummer hopes that his findings may have opened new avenues of research.
