Population mobility, urban development and dracunculiasis in Kwara State, Nigeria.

This research note reports on an on-going study of guinea worm infection, dracunculiasis, in Kwara State of Nigeria. Work already undertaken illustrates the linkage between urbanisation, population mobility and the recent rapid diffusion of the disease. Prevalence surveys are being carried out to identify the extent of the problem. Studies of local water sources and water collection practices are providing guides for disease control. Dracunculiasis is contracted as the result of drinking water containing cyclops which are infected with the infective embryo of Dracunculus medinensis. The guinea worm larvae are released into the human gut and enter the bloodstream. Within 10 months to a year an abcess or ulcer forms on the skin, often on the lower leg or foot, and the worm emerges. When a person with an infected limb puts it in water, e.g. when bathing or collecting water, many guinea worm embryos are released into the water and seek out the intermediate hosts. About 5 days after they enter the cyclops they become infective to humans who swallow them when drinking the water. The ideal habitat of the cyclops is stagnant or near stagnant water which is tree shaded and rich in decayed organic matter. In rural Kwara State, towards the end of the 5-7 month dry season, when streams have ceased flowing and many wells have dried up, infected ponds are frequently the only available sources of drinking water. Often a single infected pond serves as the source of drinking water for an entire village. Prevalence levels in a community which is using such a pond may reach 70x, yet a nearby community with a non-infected water source may be almost completely free of the disease [l]. Some guinea worm sufferers are mobile, but others may be incapacitated for up to 12 weeks as the result of secondary infections and the swelling of the affected joints, mainly the knee and ankle. The disease debilitates many farmers at the time of year when agricultural demands are heaviest, at the end of the dry season and the beginning of the wet season.