Experimental infection of the leaf-monkeys, Presbytis cristata and Presbytis melalophos with subperiodic Brugia malayi.

The leaf-monkeys, Presbytis cristata and Presbytis melalophos, experimentally infected with subperiodic Brugia malayi, have been used for studies on the pathoimmunology of the infection and the screening of potential filaricides during the last 6-8 years, and considerable information on the pattern of microfilaraemia and adult worm recoveries have been obtained. The prepatent periods in 97 P. cristata and 45 P. melalophos, each infected with about 200 infective larvae, were similar, these being approximately 70 and 68 days respectively. Although all infected animals became microfilaraemic, the peak geometric mean count was much higher in P. cristata than in P. melalophos, this being 182.0 and 65.8 per ml blood respectively. Mean adult worm recovery expressed as the percentage of the infective dose was 4.7% and 2.5%, respectively. Most worms were recovered from the sacral nodes/thoracic duct or inguinal lymph nodes in these animals. In view of the higher worm recovery and the higher peak microfilaraemia attained, it is concluded that P. cristata is a better model for the infection than P. melalophos.