Parasites May Also Be a Risk Factor for HIV
A new study finds that a disease associated with parasite-infested waters may also be a risk factor for HIV infection for women living in sub-Saharan Africa. Schistosomiasis is a parasitic disease prevalent in the fresh waters of tropical and subtropical areas. Women washing clothes and children playing in water can contract the disease when larval forms of blood flukes, known as schistosomes, enter the skin and take up residence in the blood vessels. When the worms reside in the vessels near a woman's bladder or genitals, the woman can develop female urogenital schistosomiasis (FUS), which causes vaginal itching, discharge, painful intercourse, bleeding after intercourse, and infertility.
When researchers tested and interviewed 457 women in 8 rural villages in Tanzania, they found that 5 percent of the women overall had FUS, and that the prevalence was higher in inland areas and in younger women. Further, although the HIV prevalence rate was nearly 6 percent for the area, the HIV rate was much higher—17.4 percent—for women with FUS.
The authors claim that longitudinal studies are needed to provide a causal association between FUS and HIV infection, but they offer several explanations for why the two diseases may be linked. For example, in most girls and women, FUS occurs first because schistosomal infection most often happens during childhood, before sexual activity begins. And because FUS can cause lesions on the genital tract and can disrupt the body's immune response, it seems plausible that women with FUS could be at increased risk for HIV infection. This study was funded in part by the Agency for Healthcare Research and Quality (T32 HS00066).
See "Urogenital schistosomiasis in women of reproductive age in Tanzania's Lake Victoria region," by Jennifer A. Downs, M.D., Charles Mguta, Godfrey M. Kaatano, and others in the March 2011 American Journal of Tropical Medicine Hygiene 84(3), pp. 364-36