Neglected tropical diseases

Elimination of suffering due to schistosomiasis is possible – WHO calls for concerted intensified action

01 April 2011 | Geneva

An Informal Consultation on Schistosomiasis Control convened by the World Health Organization (WHO) has reported an encouraging increase in efforts to control and eliminate schistosomiasis (bilharziasis). The 3-day meeting took place at WHO headquarters in Geneva, Switzerland, on 30 March – 1 April 2011.

A cornerstone for the elimination of morbidity due to schistosomiasis is praziquantel, the only essential medicine commercially available to treat human schistosomiasis. The meeting noted that while demand for praziquantel has been growing over the years, production has hardly increased. The demand is mainly due to growing numbers of endemic countries implementing large-scale control programmes. In 2011 alone, requests for praziquantel are set to increase from 50 million to 150 million tablets. WHO is working with partners, including Merck KGaA, to address the problem of access to praziquantel in endemic countries.

“Control of schistosomiasis can be achieved, and now we believe that even elimination may be feasible in many areas,” said Professor Alan Fenwick, Director of the Schistosomiasis Control Initiative at Imperial College London. “For example, Morocco has interrupted transmission of schistosomiasis. China and Egypt, which were highly endemic in the past, are also close to interrupting transmission after many years of effort.”

Dr Amadou Garba (Niger), Dr Narcis Kabatereine (Uganda) and Dr Seydou Toure (Burkina Faso) report that their respective countries have successfully controlled morbidity from schistosomiasis by regular implementation of large-scale treatment with praziquantel since 2003. Dr Dan Colley, Director, Center for Tropical & Emerging Global Diseases, University of Georgia, USA and Chairman of the meeting, stated “I would like to see many more countries in Africa having access to free praziquantel and implementing control programmes.”

According to Dr Charles King, Professor of International Health, Center for Global Health & Diseases, Case Western Reserve University, USA, “Schistosomiasis should really be viewed as a chronic inflammatory disorder that is caused by past or current infections with the schistosoma parasite.

Damage accumulated during childhood infection translates into permanent disease that creates long-term disability among older children and adults. Additionally, one important impact for adults is an apparent two to four fold increase in susceptibility to HIV infection. In high transmission zones, where reinfection is common, we now know that four or more praziquantel treatments are needed during the school-aged years in order to prevent both acute and chronic morbidity and disability.”

Schistosomiasis is endemic in 76 countries worldwide. Of the estimated 240 million infections, over 200 million occur (representing more than 90% of cases) in Africa. Praziquantel treatment should be scaled up in parallel with other public health measures including provision of potable water and adequate sanitation, augmented by behavioural and educational campaigns.

“I am very concerned about the shortage of praziquantel,” said Dr Lorenzo Savioli, Director of WHO’s Department of Control of Neglected Tropical Diseases. “After having seen what is possible, I am confident that the collaboration of partners will result in expanded availability of praziquantel to allow the effective control of this ancient debilitating, poverty promoting disease.”

Dr Dirk Engels, Coordinator of Preventive Chemotherapy and Transmission Control of WHO’s Department of Control of Neglected Tropical Diseases announced that WHO will convene a task force to bring together Member States, the private sector, donors and implementing partners to eliminate morbidity due to schistosomiasis. Key points to be addressed will include increasing access to praziquantel, formulating national plans and expanding implementation.