Single and repeated infections of grivet monkeys with Schistosoma mansoni: parasitological and pathological observations over a 31-month period
Cheever, A.W.; Duvall, R.H.
American Journal of Tropical Medicine and Hygiene 23(5): 884-894
1974
ISSN/ISBN: 0002-9637 PMID: 4217568 Document Number: 81212
Groups of 6 to 8 Cercopithecus aethiops aethiops were killed 3, 6 and 31 months after exposure to 600 Schistosoma mansoni cercariae each. Other groups of monkeys were repeatedly challenged with cercariae, beginning 4 or 23 months after the initial infection, and were killed 31 months after the first exposure. Pathological and parasitological data on the infections are reported. Monkeys became acutely ill about 8 weeks after initial exposure, and death was attributed to acute toxaemic schistosomiasis in 4 of 46 infected animals; acute disease did not occur with reinfection. Relatively stable infections were found after a single exposure to cercariae, with only a slight decrease in worm numbers and moderate decrease in egg passage after 31 months. With repeated reinfection, only 19% of challenge cercariae developed into adult worms. Oviposition by these worms was delayed and the rate of oviposition was substantially less than in monkeys infected only once. Eggs deposited in the tissues were rapidly destroyed. Although very heavy infections were present in repeatedly infected monkeys, only slight hepatic fibrosis was seen and no portal hypertension or portal systemic collateral circulation developed. Severe intestinal disease was present in only 2 monkeys.