Development of Dipetalonema gracile in the squirrel monkey (Saimiri sciureus), with notes on its biology

Infective larvae of Dipetalonema gracile, which had developed in Culicoides hollensis, were inoculated into 4 laboratory-born squirrel monkeys, Saimiri sciureus. Weekly blood sampling revealed the mean prepatent period to be 297 days. All 4 monkeys developed patent infections in which peak microfilaremias were reached 13 to 18 wk after patency. Two laparotomies, performed at 27 and 64 wk, were conducted to evaluate pathological involvement and, at that later time, to recover adult parasites. Slight capsular fibrosis was observed on the spleen of 2 of the animals but fibrous adhesions were absent. Microfilaremias in the 4 monkeys ranged from 15 to 250 mf/20 mm3 of blood and the number of adult parasites recovered varied from 7 to 13. However, the level of microfilaremia did not correlate directly to the number of adult parasites recovered.