A blueprint for success: integration of neglected tropical disease control programmes

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The rapid expansion of chemotherapy-based control programmes for neglected tropical diseases has been catalysed by funding from the Bill and Melinda Gates Foundation, donations of several drugs from pharmaceutical manufacturers, and the reduced price of the drug praziquantel. Focussing on lymphatic filariasis, schistosomiasis and soil-transmitted helminthiasis, we review here the progress made to date with the implementation and integration of large-scale control programmes. Unresolved issues include a means for rapid identification of communities at highest risk of co-morbidity, cost-effective approaches for integrating the technical interventions into setting-specific packages, and determination of the most appropriate and sustainable delivery systems.

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Helminth infections

Lymphatic filariasis (LF), schistosomiasis and soil-transmitted helminthiasis (STH, which includes ascariasis, trichuriasis and hookworm diseases) are caused by infections with helminths (parasitic worms, including nematodes and trematodes) and remain among the most prevalent parasitic diseases in the world 1, 2, 3. Hundreds of millions of people are currently infected and thousands of millions are at risk (Table 1) 1, 3, 4, 5, 6, 7, 8. The diseases cause untold morbidity, with the poor

Lymphatic filariasis

In 1993, the International Task Force for Disease Eradication declared LF an eliminable infectious disease [19], and in 1997 the World Health Assembly (WHA) endorsed the elimination of LF as a public health problem by 2020. Subsequently, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) and a worldwide coalition (the Global Alliance to Eliminate Lymphatic Filariasis) were established and, in 2000, large-scale operations were launched, catalysed by a grant from the Bill and Melinda

Schistosomiasis

The discovery that praziquantel was a safe and effective drug against all human schistosome species was a major breakthrough for treatment of infected people and for community-based control approaches [37]. Indeed, praziquantel became the essential tool that led to the shift in the global control strategy – from transmission containment to morbidity control – that occurred in the mid-1980s [38]. Added to this, a dramatic (>90%) reduction in price of praziquantel has occurred since 1990 and many

Soil-transmitted helminthiasis

Hookworm (Ancylostoma duodenale and Necator americanus), Ascaris lumbricoides and Trichuris trichiura are the most common intestinal (soil-transmitted) nematodes 8, 10, 48. Infections have been associated with low birth weight, maintenance of malnutrition and impaired physical and cognitive development in early childhood, poor school performance, reduced work capacity and complication of pregnancy and birth outcome 34, 36. Moreover, hookworm infections are increasingly recognized as one of the

Integrating different control programmes

The LF and schistosomiasis/STH control programmes are functioning well as separate entities and each has demonstrated measurable health benefits. However, funding constraints and remaining operational challenges (e.g. reaching remote communities) have prevented some countries from implementing programmes in all areas in need of MDA. For example, to date, less than a third of the 80 LF-endemic countries have achieved a coverage exceeding 70% of at-risk populations for LF [23]. Similarly, only

Challenges at the operational level

As new efforts are initiated to integrate programmes for NTDs [11], several issues must be addressed [61]. As a first step, because of the focal distribution of several of the diseases and the paucity of spatially explicit datasets, mapping surveys to define the degree of spatial overlap of NTDs at small units of analysis (e.g. at the village or district level) are needed. Previous efforts to collate available data from the published literature to map the distribution of schistosomiasis and STH

Issues of concern

One question that could limit integrated chemotherapy is the safety of co-administered drugs. Before combination therapy with albendazole plus either ivermectin or DEC was implemented on a wide scale for LF, enhanced surveillance for adverse events was carried out in pilot studies in different epidemiological settings [68]. Although pharmacokinetic studies sponsored by WHO and the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases suggest that ivermectin

Unanswered questions

The proposal to integrate control programmes to address the huge burden of the NTDs collectively – in a first step through administration of appropriate drug packages to identified target populations – is gaining interest 11, 17. There are several unanswered questions. First, there is considerable concern that rapid expansion of the use of drugs might facilitate the development of drug resistance. Fortunately, there is no evidence to date that clinically relevant resistance has developed in

Acknowledgements

We thank the SCI team at Imperial College London and the programme collaborators in Burkina Faso, Mali, Niger, Tanzania, Uganda and Zambia. The inspiration for this article comes from our colleagues David H. Molyneux and Peter J. Hotez. A.F. is funded through the SCI by the BMGF. J.U. is indebted to Marcel Tanner, Burton H. Singer and Don de Savigny for continued and stimulating exchange and thanks the Swiss National Science Foundation for generous financial support through project no.

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