The occurrence of microfilaria and the response of microfilaria and gut nematodes to ivermectin therapy in Myanmar timber elephants.

Filariasis is a parasitic nematode infestation characterized by the presence of micro laria, an embryonic stage between the eggs and the larvae (Haleem et al. 2002). They occur in all orders of vertebrates and are obviously of considerable antiquity, but have no close relations among the other parasitic nematodes. Little is known about their evolutionary history. They live within the body tissues of host animals. The micro lariae are removed from the body by blood-sucking insects. In some species there is a peculiar and as yet unexplained periodicity of their appearance in the peripheral blood-vessels of the host. In some cases, they appear during the hour of darkness, in others during daylight (Cameron 1965). The appearance of micro laria is thought to be in uenced by environmental conditions such as sunlight, temperature and humidity (Oishi 1975).