Experimental study of survival strategy of Haemonchus contortus in sheep during the dry season in desert areas of the Mauritania.

The survival of the most common worm of sheep and goats of desert areas, Haemonchus contortus, during the dry season is of the utmost importance. It may be achieved through long survival of adult worms that may preserve their ability to excrete viable eggs or to inhibited development in host and survival as a larval stage. Twelve lambs were experimentally infected with larvae obtained at the end of the rainy season. The resulting adult worms were able to survive and maintain their ability to produce viable eggs that developed into infective larvae up to 50 wk after infection. It is concluded that survival of adults during the dry season played a major role in transmission from 1 rainy season to the next, rather than inhibited development and survival as a larval stage.