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Initiatives to control and eliminate parasitic disease are reaching targets earlier than projected

Nearly all national control programmes for schistosomiasis across sub-Saharan Africa and Yemen have successfully met disease-control targets set by the World Health Organization (WHO), according to a new study published in the New England Journal of Medicine.
Children gathering for mass drug administration. Credit: Elizabeth Hollenberg

Schistosomiasis is a parasitic neglected tropical disease that is currently estimated to infect between 140-240 million people. Ninety percent of the disease burden is in sub-Saharan Africa. Schistosomiasis parasites are mainly water-borne and transmitted through faeces or urine. They can cause symptoms including anaemia, stunting, fever, genital lesions, and irreversible organ damage.

Current WHO guidelines set the goal of controlling this debilitating disease by 2020, and eliminate it as a public health problem by 2025, aiming for “a world free of schistosomiasis”. Currently, the only drug available and recommended by WHO for the disease is preventive chemotherapy with praziquantel.

These programmes define disease control as there being less than 5% of patients with ‘heavy-intensity’ infection in the area or health facility, and this prevalence needs to fall to less than 1% to be counted as an elimination.

In this study, the research team analysed data from nine national schistosomiasis control programmes. They found eight of the nine programmes reached the disease control threshold by two treatment rounds or less, controlling the disease in all countries but Niger.

LSHTM’s Dr Arminder Deol, who was at Imperial College London at the time, led the research. Her team worked with the Schistosomiasis Control Initiative, The Royal Veterinary College, RTI International and the London Centre for Neglected Tropical Disease Research, alongside national control programme leaders from each of the participating countries to assess the progress and evaluate these guidelines.

Dr Deol, now Research Fellow at the London School of Hygiene & Tropical Medicine, said:

“I’m excited to share the results of our paper which will enable us to improve our approach to achieving the global control and elimination targets for schistosomiasis, owing much to the hard work and dedication of staff at these control programmes. We move beyond theoretical outputs, and present empirical evidence through our partnership with the National Ministries of Health, to show that the goal of control may be reached sooner than proposed, which means that we can adjust our strategy to ensure we meet the elimination targets in time.”

However, the researchers found that the variation in overall prevalence of the disease within the countries’ population impacted the likelihood that they would reach both the control and elimination targets. This highlights the challenges of only using one metric to define control or elimination across a variety of settings.

Going forward, each country’s individual disease data needs to be taken into consideration, and their progress and treatment strategies need to be re-evaluated more frequently. This will allow researchers to more accurately determine the effectiveness of treatment and allocate resources appropriately, moving closer to achieve the global goals of eliminating this devastating disease.

Publication

A.K. Deol, F.M. Fleming, B. Calvo-Urbano, M. Walker, V. Bucumi, I Gnandou, E.M. Tukahebwa, S. Jemu, U.J. Mwingira, A. Alkohlani, M. Traoré, E. Ruberanziza, S. Touré, M-G. Basáñez, M.D. French and J.P. Webster. Schistosomiasis – assessing progress toward the 2020 and 2025 global goals. New England Journal of Medicine. DOI: 10.1056/NEJMoa1812165

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