Experimental schistosomiasis japonica in the rhesus monkey. A comparison of the Ilan (Taiwan) and Japanese strains.

The prepatent period of the Ilan strain of S. japonicum in three rhesus monkeys varied from 42 to 78 days (avg. 56.3) ; in an equal number of monkeys, the Japanese strain, from 37 to 40 days (avg. 39.3). Only 28 schistosomes were recovered from the three monkeys infected with the Ilan strain compared to 145 from the three monkeys infected with the Japanese strain. The body length of worms showed that males and females differed significantly between strains at the 5 % and 1 % levels. Miracidia were hatched from eggs obtained from livers of all the monkeys except one monkey which was infected with the Ilan strain. Comparison of the histopathological changes induced by the two strains shows similar patterns of inflammatory response, but the Japanese strain is more severe. Evidence presented shows that the rhesus monkey is susceptible to the Ilan strain of S. japonicum. Differences between the presently studied Ilan strain and the previously known Formosan zoophilic strain (the Changhua** strain) are discussed.