Epidemiology and vectors of Dracunculus medinensis in northwest Burkina Faso, West Africa.

The epidemiology of the guinea worm, Dracunculus medinensis, was studied in the dry savanna zone of West Africa. The monthly incidence data collected over a period of four years showed peak transmission occurring in June and July at the beginning of the rainy season. The different types of local water sources (i.e. wells, periodic streams, seasonal cattle waterings, natural ponds and man-made ponds) were examined for infected cyclopoid copepods. Small hand-dug ponds or water-holes situated in the fields proved to be the most important sites of transmission. While the domestic water supply is obtained from draw-wells in the villages throughout the year, the villagers take additional drinking water from these ponds during the planting season when farm activities require long stays in the fields. Four cyclopoid species were found for the first time acting as natural intermediate hosts of D. medinensis. Thermocyclops inopinus was the most frequently infected cyclopoid, and small man-made ponds are the preferred habitats of this species. Occurrence of T. inopinus is confined to the first half of the rainy season, coinciding with peak transmission. The epidemiology of dracunculiasis in dry and humid regions of West Africa is compared with regard to seasonality. The use of protective water filters proved to be the only adequate method for guinea worm control in the project area.

[Longitudinal study of Cyclopidae, intermediary hosts of the Guinea worm in the Sudano-Sahelian area (Burkina Faso)]. / Etude longitudinale des Cyclopidés, hôtes intermédiaires du ver de Guinée en zone soudano-sahélienne (Burkina Faso).

During 18 months covering two annual rainy seasons, 338 monthly water samples were taken in 29 ponds of two dracunculosis endemic villages of south-western Burkina Faso. The dynamics of ponds inhabited by Cyclopidae has been surveyed as far as their densities and their species are concerned. We identified a total number of 17 species from 6 genera of which the decreasing order in frequency is: Thermocyclops, Mesocyclops, Metacyclops, Cryptocyclops, Microcyclops and Allocyclops. The dominant species are: Thermocyclops crassus consimilis, Metacyclops margaretae, Thermocyclops oblongatus and Thermocyclops neglectus decipiens. The crowds of these major species during the period of dracunculosis high transmission in the surveyed area (June to July), suggest, in the absence of a search for Dracunculus medinensis larvae, that, they should play the principal part as vector of the parasite in this area.