Distribution, behavior, and course of patency of Dracunculus insignis in experimentally infected ferrets.

From 106 ferrets experimentally infected with Dracunculus insignis, 273 female worms and 42 male worms were recovered. The percentage of female worms that mated, the location of all worms, and the rate of emergence of gravid females were recorded. Of 174 mature female worms recovered, only 11% had emerged before necropsy. Eighty-one percent of the male worms and 87% of all unmated (immature) females were found on the trunk of the animal or on the skin overlying it. Gravid female worms were found on the extremities (legs) 88% of the time. Almost one-third of gravid female worms were found on the left front leg. On 4 occasions, females were found in unusual locations: the tail, the cheek, the lumbar region of the spinal cord, and the peritoneal cavity associated with the omentum. The results showed that only a small percentage of mature female worms emerge, which suggests that infected persons harbor many more gravid female worms than indicated by reports of emergent worms. More than one-third of female worms were not mated, but it is likely that these immature females would be capable of further development. Furthermore, male worms have been observed to survive for up to 330 days, suggesting that male or unmated female worms may carry over from one transmission season to the next.