[Experimental infection of Galba pervia, Radix swinhoei and Physa acuta with Fasciola hepatica in Dali, Yunnan].

OBJECTIVE

To determine the intermediate host of Fasciola hepatica in Dali of Yunnan Province, and investigate its development and characteristics.

METHODS

F. hepatica eggs from cattle were collected from July 2012 to July 2013, and placed in 28 degrees C water bath for incubation. Galba pervia, Radix swinhoei, and Physa acuta were collected from Dali, and used to be infected with F. hepatica in the laboratory. Trematode infections were excluded from the snails before experiment. All the snails were infected with F. hepatica miracidia, reared in mud pots. Dead snails were dissected for observing the development of F. hepatica. The metacercariae were collected and identified by PCR amplification of partial sequence of mitochondrial cytochrome oxidase subunit I (COX1) gene.

RESULTS

A total of 1 146 R. swinhoei, 996 P. acuta, and 3 307 G. pervia snails were infected with F. hepatica, respectively. Mother rediae were found in two R. swinhoei snails, but no child rediae were observed in the snails. No larval forms were found in P. acuta. G. pervia was infected by F. hepatica with an infection rate of 27.2% (900/3307). The miracidium escaped from the egg and penetrated into G. pervia at temperature 22 degrees C, developed into a sporocyst after 7-15 days, which transformed into mother redia at the 11 st-20th day post-infection. The mother redia developed into daughter redia at the 30th-37th day, and produced cercaria with longtail, and became metacercaria at the 42nd-55th day. PCR confirmed that the metacercariae were that of F. hepatica, with an obvious band (approximately 500 bp).

CONCLUSION

Among the three potential intermediate hosts in Dali, G. pervia is experimentally infected with F. hepatica.