Schistosomiasis: We need to treat younger and better

By Amaya Bustinduy, St George’s University

Currently millions of praziquantel tablets are being delivered to school age children across sub-Saharan Africa for the treatment of schistosomiasis.  Although this is itself is a fantastic achievement thanks to the relentless efforts of a very dedicated community of researchers, policy makers at WHO and on-the ground personnel from in country national health programmes, there is still much we need to know about this drug. For one, praziquantel dosing is being delivered to children but using adult dosing since there were no studies conducted in children.  As it becomes more and more apparent that young children less than five years of age should also be included in control efforts, this becomes a potentially dangerous problem.

To tackle this issue, I joined Russell Stothard at Liverpool School of Tropical Medicine to lead the first praziquantel study in young African children.  This was carried out in Lake Albert, Uganda, an area known to be particularly a ‘hot spot’ for the transmission of schistosomiasis. The breathtaking beauty of a lake that is swarming with larval stages of the parasite contrast with the clinical manifestations that are found in most of the children living along the lake shore.  As the paediatrician on the ground, I documented extensive morbidity related to schistosomiasis that ranged from anaemia, growth retardation as well as liver fibrosis seen in very young children.

The work was intense, as we had to keep the children in our research facilities for over a day.  We asked the mothers to stay with them and sometimes some young babies as well, so our study site was a family camp where we performed the delicate work of measuring praziquantel in young children’s blood every few  hours for 24 hours.  The side effects of praziquantel are particularly unpleasant and this is worse if the child is heavily infected.  An important part of the team’s work was to keep children as comfortable as possible.  At the same time we were keeping our facilities organized and well kept which is a challenge when power is dependent on a noisy generator always thirsty for fuel. We had to take care of parallel housekeeping activities such as food, lodging and entertainment. Evening songs and dances kept the spirits high for both families and staff members.

And the efforts led to meaningful results.  Our analysis showed that children younger than five years of age may need almost double the WHO recommended dose of praziquantel.  As we integrate preschool children in mass drug administration programmes, getting the dose right is essential. In parallel, there is a paediatric praziquantel formulation in development that will help deliver the adequate dose without the risk of choking that the large current praziquantel tablet has.  Repeating doses at six weeks would also be something to consider to target more immature forms of the parasite that would get untreated after the first dose.  Also in hot spots, treatment more than once a year would allow us to target reinfection.

There is a perceived momentum in getting treatment for children of all ages on the international agenda. As we get the praziquantel dose right and the adequate formulation there can be no more excuses for excluding the very young from a treatment they deserve.

Ed: The image used above was taken by Amaya at the study site. Please credit her if you reuse it.

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