Many Neglected Tropical Diseases: What About Eliminating Them?

Testing to see if transmission of lymphatic filariasis has stopped in Burkina Faso

Two things we need to note about the list of 20 diseases that the World Health Organization and partners classify as Neglected Tropical Diseases (NTDs). First, diseases like Rabies, Snakebite/envenoming, and Leprosy, while certainly more common in the tropics now, have in the past been global in distribution. Secondly some of the diseases have not been neglected. Onchocerciasis or river blindness has been the focus of a global partnership since 1975, and transmission in the America’s and much of the Sahel in Africa has been halted. Elimination of Dracunculiasis or Guinea Worm has also been the subject of many World Health Assembly Resolutions, and concerted effort has brought the number of cases down from 3.5 million in 1986 to 30 in 2017.  What is more to the point about these diseases is that they affect neglected people, the poor and vulnerable in remote rural areas or urban slums.

Still when we can compare NTD control programs with the rise of major disease control efforts like the Global Fund to fight AIDS, Tuberculosis and Malaria, the President’s Emergency Program For AIDS Relief, the President’s Malaria Initiative, World Bank Malaria Booster Program, Global A Vaccine Initiative among others, we can see that the global community has been able to focus major financial resources on a few diseases.  Now with the Sustainable Development Goals, that focus expanded from infectious to Non-Communicable Diseases.  It is natural therefore to fear that tropical health problems that are responsible for major loss of life and economic capacity will not be adequately addressed.

A system of rewards helped identify the last cases in many guinea worm endemic countries

Based on the World Health Organization’s 2020 Roadmap on NTDs, the London Declaration on NTDs recognized a “tremendous opportunity to control or eliminate at least 10 of these devastating diseases by the end of the decade” (i.e. by 2020). These include eradication of Guinea worm disease, and elimination by 2020 of lymphatic filariasis (LF), leprosy, sleeping sickness {human African trypanosomiasis) and blinding trachoma. In addition drug access programmes should help control by 2020 schistosomiasis, soil-transmitted helminthes (STH), Chagas disease, visceral leishmaniasis and river blindness (onchocerciasis).

Five of the diseases are notable in that they can either be controlled or eliminated through Mass Drug Administration (MDA) using Preventive Chemo-Therapy (PCT). This effort is aided by drug donation programs at the global level and community based MDA at the local level. Ten companies were signatories to the London Declaration and contributed to drug donation programs to achieve MDA. According to WHO,

Preventive chemotherapy is aimed at optimizing the largescale use of safe, single-dose medicines and offers the best means of reducing the extensive morbidity associated with four helminthiases (lymphatic filariasis, onchocerciasis, schistosomiasis and soil-transmitted helminthiases) (6). Additionally, the large-scale administration of azithromycin – a key component of the SAFE strategy for trachoma (that is, lid surgery (S), antibiotics to treat the community pool of infection (A), facial cleanliness (C) and environmental improvement (E)) – is amenable to close coordination and, in future, possibly co-administration with interventions targeted at helminthiases.

Community health workers are the cornerstone of many NTD elimination programs

Targets for the 5 PCT diseases vary. The aim is to eliminate LF and Trachoma by 2020. Although the efforts against onchocerciasis have been running the longest, the refocus from control to elimination meant increasing the geographical scope of intervention, and now elimination may not be feasible until 2025.  With a focus mainly on the school aged and based populations, programs against schistosomiasis and STH talk of control, not elimination, although some endemic countries hope that elimination may be possible if the focus of these programs expands. So far, Togo is the only Sub-Saharan African country to have eliminated LF, and Ghana to have eliminated Trachoma.

Partnerships, funding and drug donations need to be strengthened if more countries are to join the ranks of Togo and Nepal.

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