By Dr. Alan Fenwick, Director of the Schistosomiasis Control Initiative at Imperial College, London
An estimated 120 million people in sub-Saharan Africa are currently infected with one of the seven most common NTDs, schistosomiasis, and many more are at risk. Of these, over 40 million are female. One of the complications of one type of schistosomiasis (S. haematobium) is that the worms and their eggs invade the female genital system and can cause visible lesions. These lesions associated with S. haematobium infection in the female genitals are mucosal grainy sandy patches that are usually associated with bleeding, especially “contact bleeding” during pelvic examination or sexual intercourse (Hotez et al 2009 PLOS NTDs pE340).
So an estimated 40 million females (approximately 28 million of whom are school aged) in sub-Saharan Africa are at risk of having lesions on the cervix due to untreated schistosomiasis infection, and as a result, women with cervical lesions are at much higher risk of contracting HIV during intercourse than women without these lesions. Indeed, a cross-sectional study from a rural Zimbabwean community revealed that women aged 20 to 49 with genital schistosomiasis exhibit a three-fold risk of having HIV relative to women without the infection (Kjetland EF, et al. Association between genital schistosomiasis and HIV in rural Zimbabwean women. AIDS 2006; 20: 593-600).
In a recent paper, Peter Hotez and his co-authors not only highlighted these facts but pointed out that for just 32 cents per person per year, all school-aged girls in endemic areas could be treated with the drug praziquantel – a safe oral drug which, when taken annually, will keep schistosomiasis infection at bay and therefore prevent the cervical lesions that promote HIV infection.
In countries such as Burkina Faso, Kenya, Mozambique, Niger, Nigeria, and Tanzania, S.haematobium is widespread and in some areas almost 100% of the school aged populations are infected. In these countries alone, perhaps over 200 million people are at risk of schistosomiasis. A simple programme to deliver praziquantel to every child at school, supplemented by an outreach programme to reach non-school attenders, could be effectively implemented at minimal cost. The drugs are safe and effective and do not need medical supervision for delivery. A short one-day training course for teachers is enough to ensure safe and effective drug distribution.
This is not theory because it has been shown to work. The delivery of praziquantel not only to school children but also to other high risk groups such as farmers and fishermen has been successfully carried out in six countries in Africa since 2002-2006 (Fenwick et al July 2009 Parasitology special issue pp 1-12). Building on this success, USAID has funded a wider programme targeting schistosomiasis and other tropical diseases through its NTD Initiative, leading to even more treatments delivered. However schistosomiasis is still a neglected disease and in 2009 it is estimated that only 10% of those infected will be offered treatment – leading to more women developing cervical lesions and contracting HIV.
Successful results have been reported on several websites including www.who.int/wormcontrol ; www.sci-ntds.org ; http://ntd.rti.org/ and www.globalnetwork.org
HIV is a disease that is still incurable today. We should always practice safe sex and also educate our people how to avoid the spread of this disease.