Abstract:

AIM:To carry out a biological comparison of various geographical strains of Schistosoma japonicum in Asia in the same laboratory. METHOD: Under the same condition and with the same permissive host, some biological characteristics were extensively compared among the following seven geographical strains of S. japonicum , i. e. Chinese Yunnan (Y), Chinese Guangxi (G), Chinese Sichuan (S), Chinese Anhui Hubei (A), Chinese Taiwan (T), Japanese (J) and the Philippines (P).RESULTS: With the same quantity of cercariae exposed, the mean prepatent period denoting the time elapsed between exposure of the host and the beginning of the appearance of eggs in the faeces was 45.1±3.2 days in C57BL mice infected with Chinese Taiwan strain, a zoophilic strain of S. japonicum, while that of other six strains, anthrophophilic strain, was less than 39.4±1.4 days. In the case of morphometric data, both body and tail indices of cercariae from Philippines, Japanese, Chinese Taiwan and Chinese Yunnan was smaller than those of other strains and the body length of mature worm pairs especially females was also shorter than those of others. The percentage of male specimens with 7 testes from strains of Philippines and Chinese Yunnan was significantly lower than that of other 5 strains, suggesting that great intraspecific and interstrain variations exist in the number of the testes in S. japonicum . Our results show that the embryonated egg index (width/length×100) among seven strains of S. japonicum from Asia was 67 77 in average. CONCLUSION: Significant differences were observed in some morphometry and in the prepatent period of their mammalian hosts infected with various strains of S. japonicum .