Tailoring Mass Drug Administration to at risk communities

By Alan Fenwick (Schistosomiasis Control Initiative (SCI) Imperial College London)

In terms of schistosomiasis control with Mass Drug Administration (MDA) of the drug praziquantel there is a need to target those who are most vulnerable to infection – those people who come into the greatest contact with infested water. The profile of treatment should be driven by its health consequences which can include: malnutrition and anemia; growth retardation; cognitive impairment; increased susceptibility to other infections; chronic health problems such as inflammation and fibrosis of the bladder wall, colon, liver, spleen, lungs; and life threatening consequences such as bladder cancer, portal hypertension, and hematemesis. In the case of some of these life threatening consequences it can be quite challenging to trace the cause back to swimming in a pond 20 years ago, especially in communities that have an incomplete understanding of the disease.

In 2000 there were no MDA programmes for schistosomiasis, now look at where we are!

We currently target our programmes in the manner which is simplest – by administering drugs to children in schools. Children tend to be responsive to their teachers who deliver treatments against schistosomiasis and intestinal helminths in settings where governments don’t stipulate that medical attendance is mandatory. Administering the medicine is fairly simple as they are taken orally – although praziquantel tastes quite bitter and children sometimes vomit if they chew the tablet when they take it. With sufficient training MDA is easy to establish as the front line method of control in resource poor areas, but we need to ensure that the delivery of drugs is best targeted and sustained  within at risk populations.

We know that pre-school children are often bathed in infected water and are therefore also vulnerable. But as a rule we don’t treat them, because of the large bitter tablet. But emerging research shows that more and more younger children are getting infected, and because of the small size of their bodies immense damage can be done by the worms and their eggs to the children’s internal organs, and some may never recover from it. Expanding treatment coverage to younger children is becoming more feasible with the development of paediatric formulations by Merck so there is now good reason to expect change for the better

In 2012 only 14.4% of the people worldwide who needed praziquantel treatment actually received the drug. That amounts to 42.1 million people. However, until quite recently one of the barriers to scale up was the accessibility of treatment. That argument no longer holds as we estimate that by 2016 we will have enough donated drugs from Merck, DFID, USAID and World Vision to treat 165 million people.  Now we have a new problem, we face financial constraints to fund delivery – the UK and the US are currently the only bilateral donors that are funding the delivery of drugs and the main financing burden falls on the governments of low- and middle-income countries who don’t always prioritise NTDs. That being said we are in a better position than ever before and are optimistic in future expansion of our operations

Scaling-up control to those who need treatment, however, will depend on a number of factors: on improving country political will and resources; on praziquantel availability; and on accurate geographical and epidemiological mapping that enables the development of evidence based national plans. To make this a reality advocacy needs to occur at the national and district level, and this work needs to be done well in advance. It can take up to six months for WHO to fulfil requests for drug donations, but creating systems and the training of those who will deliver the programmes takes time, so these tasks need to go in parallel. Other tasks may include ensuring that there is ethical clearance from the parents and caregivers of those who will be treated and we need to be ready in case there are any adverse events, however mild, with sufficient supporting community dialogue and assurance.Today we are poised to expand coverage of praziquantel treatments and improve the present and future quality of life of hundreds of millions of children in Africa, but we have only a small window of opportunity to get it right so we have to rise to the challenge.

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