Studies on dracunculiasis in the Indian Desert

Dracunculiasis (infection by the guinea worm,Dracunculus medinensis) has been a major rural waterborne problem in many areas of arid western Rajasthan. The presence of temporary ponds in endemic areas offers a peculiar habitat to cyclops, the vector of the disease. Cyclops can withstand drying of the ponds and regain viability when ponds refill during rains. Cyclops shows a diurnal cycle of migratory movements under natural as well as experimental conditions. The species of cyclops acting as intermediate host in endemic areas isCyclops atter. This carnivorous species is highly predatory on the infective first stage larvae ofD. medinensisin experimental infection trials. Survival of infective guinea worm embryos in free-living form till ingested by vectors is favoured by an alkaline pH of the water. Measurements of water volume in ponds, removal of soil from dry ponds to discard cyclops eggs and recording the visit history of guinea worm patients are suggested as useful additions to an eradication programme against dracunculiasis. Literature concerning epidemiological, vector-biological, and parasitological aspects of dracunculiasis as relevant to desert districts of Rajasthan is reviewed.