Epidemic typhus infection in cynomolgus monkeys (Macaca fascicularis).

A nonhuman primate model of clinical Rickettsia prowazekii infections was developed in cynomolgus monkeys (Macaca fascicularis). Monkeys infected intravenously with 10(7) plaque-forming units developed clinical signs of illness and pathological changes characteristic of epidemic typhus infection in humans. Increases in total leukocyte counts, serum alkaline phosphatase, blood urea nitrogen, and serum glutamic pyruvate transaminase values were observed. Microscopic examination revealed typical typhus nodules in the brains of two monkeys that died. These data indicated that the cynomolgus monkey is a suitable model for study of the pathogenesis of epidemic typhus infection and may prove valuable in the evaluation of candidate R. prowazekii vaccines.