[Studies on the strain differences of Schistosoma japonicum in the mainland of China. II. Susceptibility of mammalian hosts].

Six species of animals were percutaneously exposed to cercariae obtained from pools of naturally infected snails from different isolates of S. japonicum in the mainland of China as shown in Tables 1 and 2. Our results indicated that with the exception of rat, all animals under study were permissive host though their worm recovery rates varied with different isolates. The mean prepatent period in different host species were 35.0 +/- 0.8 to 36.4 +/- 1.0 days for Anhui isolate; 34.5 +/- 1.2 to 36.4 +/- 1.2 days for Hubei isolate; 34.5 +/- 1.3 to 35.8 +/- 0.6 days for Sichuan isolate; 35.1 +/- 1.0 to 37.3 +/- 1.9 days for Guangxi isolate and 36.1 +/- 1.9 to 37.8 +/- 0.8 days for Yunnan isolate. In general, the prepatent period was longer in the C57 BL inbred mice, hamsters and rhesus monkeys infected with Yunnan and Guangxi isolates, than that with Sichuan isolate. This result also indicates that the prepatent period of the strain of S. japonicum defined by Dr. Vogel as a Chinese strain which had been originated from the cercariae in infected Oncomelania hupensis hupensis snails from Jiaxing, Zhejiang (Kashing, Chekiang), China, and established in Tropeninstitut in Hamburg since 1937 by repeated passages in dogs and laboratory-bred O. h. hupensis snails, was 5-8 days longer than that of all the isolates under our study, probably due to some behavioral change. We suggest, therefore, that the Vogel's stock of S. japonicum should be termed as "Chinese Vogel strain".