OBSERVATIONS ON ONCHOCERCA-GIBSONI AND NODULE DEVELOPMENT IN NATURAL-INFECTED CATTLE IN AUSTRALIA

Abstract

O. gibsoni worms were extracted from 185 nodules of a total of 370 worm nodules collected from 94 naturally infected cattle at Townsville, Australia. Of the 185 nodules, 183 contained a single female worm; 60% of them contained a single male worm and 7% contained 2 male worms. Nodules containing males alone were not found. Small nodules (< 0.2 g) contained immature female worms without microfilariae and no males. As nodule size and female worm size increased, the number of female worms with microfilariae and the number of nodules with males increased reaching almost 100% in nodules weighing greater than 3.0 g. Female worms normally become encapsulated when young, grow within the nodule and the male enters the nodule later, fertilizes the female and remains in the nodule.