Experimental Brugia malayi infections in the rhesus monkey

Twenty-eight rhesus monkeys in 3 groups were exposed to single (Group I), double (Group II), and multiple (Group III) inoculations with B. malayi infective larvae. Infections were monitored by microfilarial and blood counts, selected biochemical tests, IFA responses, and records of body temperature and lymphadenopathy before and/or after treatment with DEC. As a whole, the highest microfilaraemia levels were observed in Group II and lowest in Group III monkeys. Eosinophilia was a common occurrence but reached the highest mean levels in Group III. Intermittent fevers and lymph node enlargements were observed in all groups of monkeys and the occurrence of these appeared to be correlated. No definite pattern of antibody production was discernable among groups, but an inverse relationship existed between microfilaraemia and detectable microfilarial antibodies. Treatment with DEC produced a microfilaraemia-taxic effect within the initial half hour and responses to treatment varied according to individuals. Although post-treatment reinfection appeared to cause lymphoid responses and tissue eosinophilia, no substantial resistance to reinfection was observed.