PLOS NTDs editor-in-chief Peter Hotez highlights the subject of Female Genital Schistosomiasis in Africa that continues to affect women there heavily, yet receives disproportionally little attention.
Last month, together with Prof. Paul Brindley I wrote about new advances in the study of schistosomiasis caused by Schistosoma haematobium, best known as the cause of urinary tract schistosomiasis and bladder cancer in Africa. Our article highlighted new animal models, the development of in vitro systems, and the recent completion of the S. haematobium genome leading to recent insights into parasite-induced carcinogenesis. Compared to the other schistosomes S. haematobium has been relatively neglected by the scientific community in terms of number of citations in the scientific literature, especially since it is the world’s most common schistosome responsible for approximately two-thirds (actually 67%) of the schistosomiasis cases in sub-Saharan Africa where more than 90% of the disease burden occurs.
In this and several other articles published in PLOS Neglected Tropical Diseases since 2009 we have tried to consistently emphasize the disproportionate impact of S. haematobium infection on girls and women. Schistosome eggs embolize to the uterus, cervix, and lower genital tract of girls and women to form fibrotic nodules known as “sandy patches” that result in a condition known as female genital schistosomiasis (FGS), which is associated with bleeding and pain (especially during sexual intercourse), as well as social stigma and depression. I have also written about FGS in the lay press.
Some preliminary calculations provide cause for concern about the high prevalence of FGS. Using the World Health Organization’s conservative estimate of 235 million cases of schistosomiasis or revised estimates from Prof. Charles King of 586-659 million people living with some form of schistosomiasis, and the fact that more than 90% of the global cases occur in sub-Saharan Africa, we can determine that between 200 million and 600 million people suffer from schistosomiasis in sub-Saharan Africa. Assuming an equal sex distribution these numbers equate to approximately 100-300 million girls and women affected by schistosomiasis. Using the 67% number for the percentage of cases caused by S. haematobium, there are approximately 67-200 million cases of S. haematobium infection among girls and women. Further estimates that between 33%% and 75% of girls and women with S. haematobium infection also suffer from FGS in their lower genital tract would indicate that between 20 million and 150 million girls are affected, possibly making FGS one of the most common gynecologic conditions in sub-Saharan Africa where it is a horrific and widespread cause of bleeding, pain, depression, and stigma.
To make matters worse are two important studies led by Drs. Eyrun Kjetland of the University of Oslo and Jennifer Downs of Weil Cornell Medical College, respectively, indicating that FGS is associated with a 3-4 fold increase in acquiring HIV/AIDS during sexual intercourse (reviewed in ref 6) so that FGS may represent one of the most important co-factors in Sub-Saharan Africa’s HIV/AIDS epidemic. Shown in Fig. 1 is a comparison of the geographic distribution of both S. haematobium infection and HIV/AIDS, which was previously published in PLOS Neglected Tropical Diseases. The map highlights the geographic overlap of these two infections especially in countries such as Malawi, Mozambique, Tanzania, and Zimbabwe.
Despite the facts that S. haematobium infection could represent one of sub-Saharan Africa’s most common gynecologic conditions affecting up to 150 million girls and women and its importance as a co-factor in HIV/AIDS transmission, overall the global health policymakers have demonstrated a mixed track record about taking on FGS. To be sure, both the United States Government through its US Agency for International Development (USAID) Neglected Tropical Disease Program and the United Kingdom through its Department for International Development (DFID) have supported rapid impact packages of NTD medicines that include praziquantel for schistosomiasis, and there is widespread support and assistance for this approach from the World Health Organization’s Department of Neglected Tropical Diseases. There is even an important public private partnership – the Schistosomiasis Control Initiative (SCI) – largely devoted to mass drug administration of praziquantel, together with a recent World Health Assembly resolution on schistosomiasis. In contrast, the major HIV/AIDS donors, advocates, and antiretroviral treatment implementers have been slow to adopt praziquantel (despite the fact that the drug is now being partially donated free-of-charge) and embrace extremely low-cost schistosomiasis preventive chemotherapy approaches into their remit. Similarly, FGS has been barely mentioned, if at all, in most of the global initiatives dedicated to girls and women living in poverty. Additional efforts at developing a vaccine to prevent FGS have been inconsistently and only modestly funded.
As we look past the Millennium Development Goals starting in 2015, it will be essential to renew a global commitment to the treatment and prevention of FGS, and spotlight attention to this ancient scourge of girls and women.