COUNTDOWN at WHO: The treatment gap in young children with schistosomiasis

By Russell Stothard

I was pleased to attend an informal WHO meeting (from the 29-30th September) where we reviewed and discussed the treatment needs of pre-school-aged children with schistosomiasis. Having chaired a similar meeting five years ago, it is now very clear that young children can catch schistosomiasis, even within the first few months of life, and can then go on to develop chronic disease even before reaching school-age. This highlights an important gap in current control strategies as children typically have their first access to praziquantel (PZQ), our only available drug treatment, once enrolled into primary school. School-based treatment campaigns operate under the auspices of national control programmes where school teachers administer PZQ treatment en masse each year. Access to PZQ aims to arrest later disease development but sadly for some children, there is already significant, perhaps irreversible damage, upon entry into school so their first treatment is already too late.

This raises two important questions with this donated medicine; why is PZQ not currently available to young children today and what can be done in future to redress this medical inequity or treatment gap? During the two-day meeting several studies were presented, including those undertaken by myself and colleagues in Uganda where intestinal schistosomiasis was shown to cause significant childhood anaemia and liver fibrosis. Later discussions framed and explored answers to these questions. The ‘why’ was relatively easy to explain; health surveillance systems have been woefully weak and failed to notice and report the occurrence of infection and disease in young children. Only after conducting targeted parasitological and epidemiological surveys, for which there are now several publications within the peer-review literature, has sufficient evidence now accrued to confidently ring that alarm bell.

This has firmly focused attention on this vulnerable paediatric group and the need to revise health policies but revealed disconnects and lack of effective dialogue between various influential stakeholders. For example, pregnant women can have schistosomiasis, and should be treated, yet even within high endemic areas PZQ is not embedded within routine antenatal care. Once the child is born, PZQ is not on the essential drug list within frontline primary child care whilst other drugs, such as mebendazole (used for treatment of soil-transmitted helminthiasis), are. This deficit is further compounded by major health players, e.g. UNICEF, continuing to overlook this disease or are simply unable to revise their stance.

About the ‘what’; well, I am glad to report that pharmaceutical sector has responded with the creation of the paediatric praziquantel initiative. Presently PZQ comes in large, unpalatable tablets for younger children. Hence a first step has been to develop an orally dispersible tablet (ODT) formulation with taste masking which will make administration easier. However, this formulation needs some clarification of its original drug licensing as children under four years old were not included in its formal clinical indication. Hence some new clinical trial data are required for this ODT, as well as, information concerning the stability of the ODT in tropical conditions e.g. sufficient resilience to high temperatures and humidity. The good news is that the project is set to deliver on its goals and is currently held on target to produce an ODT by late 2019 with an associated access plan.

But what about the children already infected – is it ethical to wait a further 4-5 years before expanded access to a paediatric formulation can begin? I don’t think so.  Therefore I was happy to see that an outcome from this meeting was to encourage the use of crushed and broken PZQ tablets. To do so is certainly within the remit of national control programmes but some further convincing may be needed for action in other health sectors, i.e. within maternal and child health clinics. To that end I firmly expect that our future studies on schistosomiasis in COUNTDOWN will pave a better way for access to PZQ in both young children and their mothers.

To ensure that a wider selection of international donors and agencies are fully aware of these issues and our intentions, we are hosting a break-out session within the COR-NTD this October where our future research uptake strategy will be honed.

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