Filarial nematodes are an important group of human pathogens infecting around 150 million people throughout the tropics with more than 1.5 billion at risk of infection. Filariasis accounts for some of the most debilitating global diseases that affect the ‘poorest of the poor’ resulting in a profound socio-economic impact on the most vulnerable in society. Control of filariasis currently relies on mass drug administration (MDA) programmes based on the generous drug donation programmes for Mectizan® (ivermectin – Merck and Co. Inc) and albendazole (GlaxoSmithKline).
These drugs are administered either singly (ivermectin for onchocerciasis) or in combination (for lymphatic filariasis in Africa, or with diethylcarbamazine [DEC] for the rest of the world) by community-directed treatment. These drugs need to be taken for extended periods to cover the reproductive lifespan of the long-lived adult worms. Programmes for onchocerciasis control, (APOC and OEPA) together with lymphatic filariasis (GPELF) have been established to promote and sustain the application of MDA to affected communities. Two of the major constraints of programme success are:
- (i) the absence of a drug with permanent sterilization
- (ii) worms developing drug-resistance