Schistosomiasis and HIV Acquisition
CHAPEL HILL, NC—Suppose one spent about $3.8 billion each year for a decade to combat HIV infection in sub-Saharan Africa. Now, suppose that instead, one spent $11.2 million—million, not billion—every year for a decade to help prevent HIV infection.
Potentially, there is an opportunity to make that prevention investment, now that a comprehensive review has confirmed a long-suspected link between female genital schistosomiasis (FGS) and HIV infection in southern Africa.
The authors of this paper, “Association between Schistosoma haematobium Exposure and Human Immunodeficiency Virus Infection among Females in Mozambique,” published online in March 2016, in The American Journal of Tropical Medicine and Hygiene [1], argue that the study’s findings offer a significant potential cost savings for governments and global donors. Treatment for FGS (de-worming 70 million African children twice a year for a decade) would cost significantly less than treating HIV infection once it has occurred. The authors cite estimates that de-worming would cost about $112 million over 10 years, versus an estimated $38 billion PEPFAR would expend in the same period.
The study, a comprehensive review of secondary data sources, has confirmed the link in Mozambique, finding that exposure to schistosomiasis, combined with HIV prevalence, increases the odds of HIV infection by three times. Researchers conclude that treating young girls with parasitic-fighting drugs such as praziquantel, could avert millions of new cases of HIV at far less cost than treating HIV.
- School children in Niger with gross hematuria (blood in urine) caused by schistosomiasis (photo by Jurg Utzinger)
Some have argued for better links between programs of parasite control and global HIV and AIDS programs, such as the President’s Emergency Plan for AIDS Relief and the Global Fund to Fight AIDS, Tuberculosis, and Malaria. Peter Hotez, MD, and Megan Whitham made that explicit suggestion in Obstetrics & Gynecology, published by the American College of Obstetricians and Gynecologists (January 2014). In fact, they cite a modeling study in Zimbabwe, which indicates that mass treatment of schistosomiasis, especially among girls, would be highly cost-effective and even cost-saving as a means to prevent HIV and AIDS in Africa. [2]
Schistosomiasis is a fresh water-borne parasitic infection, usually contracted in childhood through activities such as swimming, bathing, fishing, and fetching water. In 2014, it was estimated to affect 220 million people in sub-Saharan Africa. A 2014 report on schistosomiasis in Malawi [3] stated that “Schistosomiasis ranks second only to malaria among the parasitic diseases affecting humans with regard to the number of people infected and the risk of becoming infected globally.”
Domestic chores can place girls and women at greater risk of contracting FGS, which, the researchers say, may help explain the fact that only in sub-Saharan Africa are HIV infections higher among females than among males.
The authors, Paul Henry Brodish and Kavita Singh, conducted the study for MEASURE Evaluation, funded by the U.S. Agency for International Development (USAID) and the President’s Emergency Plan for AIDS Relief (PEPFAR), a project of the Carolina Population Center of the University of North Carolina at Chapel Hill (UNC).
Researchers confirmed the link in Mozambique by investigating two high-quality secondary data sources on HIV prevalence and FGS: the 2009 National Survey on Prevalence, Behavioral Risks, and Information about HIV and AIDS in Mozambique (INSIDA) and the Global Neglected Tropical Diseases (GNTD) open source database. Their results can reasonably be applied generally to sub-Saharan Africa and perhaps especially to South Africa, Tanzania, and Zimbabwe, where field studies also showed woman with compromised vaginal tissue due to FGS were three times as likely as their neighbors to be infected with HIV.
Two decades of studies have indicated that HIV/AIDS can be exacerbated by co-infection with neglected tropical diseases (including schistosomiasis), which weaken immune systems, increase susceptibility to other infections, and lower the effectiveness of antiretroviral therapy (ART). These results are additional evidence supporting the link between neglected tropical diseases (NTD) and HIV and the need to scale up treatment for NTD and for increased access to improved water sources.
The authors suggest further studies are necessary in other locales where there is high HIV prevalence and endemic NTDs. The researchers say the study is limited by its indirect assessment of exposure to FGS (S. haematobium) and that the availability of mass drug administration in various survey regions is not known. However, both of these limitations would tend to make it more difficult to draw an association between FGS and HIV infections.
The study is also significant on a global scale, as the Sustainability Development Goals (SDG), USAID’s goal of an AIDS-free generation (AFG), and prevention of mother-to-child transmission of HIV (PMTCT), will be that much more attainable if HIV infection can be curtailed in sub-Saharan Africa—where 60 percent of new cases are female and mostly young.
[1] Brodish, P., & Singh, K. (2016), Association between schistosoma haematobium exposure and human immunodeficiency virus infection among females in Mozambique The American Journal of Tropical Medicine and Hygiene, 15-0652, Retrieved from http://www.ajtmh.org/content/early/2016/03/10/ajtmh.15-0652.
[2] Ndeffo Mbah M., Poolman, E., Atkins, K., Orenstein E., Meyers, L.A., Townsend, J., Galvani, A. (2013) Potential cost-effectiveness of schistosomiasis treatment for reducing HIV transmission in Africa—the case of Zimbabwean women. PLoS Neglected Tropical Diseases, 7:e2346. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/23936578
[3] Makaula, P., Sadalaki, J., Adamson, S.M., Sekeleghe, K., Jemu, S., Bloch, P. (2014). Schistosomiasis in Malawi: a systematic review. Parasites & Vectors, 7:570, Retrieved from http://www.parasitesandvectors.com/content/7/1/570
