[Role of goat in transmission of schistosomiasis japonica Ⅳ Schistosome development in goat and egg count and distribution in goat feces].

OBJECTIVE

To describe the growth and development of Schistosoma japonicum in goat and the intensity and temporal distribution of eggs excreted by goat feces, so as to provide baseline data for the control and elimination of the role of goat in the transmission of schistosomiasis.

METHODS

The goat animal models of schistosomiasis were established, and stool samples were collected for parasitological examinations. The number of adult worms recovered, variation of schistosomes in goat at different time points post-infection, number of eggs in schistosomes, variation in number and temporal profiles of eggs excreted from goat feces were observed.

RESULTS

Of the 6 schistosome-infected goat, 415 adult worms were recovered, with a mean adult worm recovery of 34.58% (range, 23.00% to 45.50%). Among the 5 goat infected with 200 cercariae each, 47, 93, 77, 74 and 73 adult worms were recovered 2, 5, 8, 11 and 14 months post-infection, respectively. There were (200.00±42.33), (226.20±45.88), (168.20±25.85), (183.80±55.13) and (190.80±53.53) eggs detected in female schistosomes. The mean prepatent period of eggs excreted by 10 infected goat was (37.7±3.02) d. From 2 to 14 months post-infection, 7 batches of goat feces were hatched, and there were 30, 23, 14, 1 and 2 times for miracidium intensity of "++++", "+++", "++", "+" and "-", respectively, with 42.86%, 32.86%, 20.00%, 1.43% and 2.86% constituent ratios of miracidium intensity.

CONCLUSIONS

Approximately 1/3 S. japonicum cercariae may develop to adults in goats post-infection, and the prepatent period of eggs is (37.7±3.02) d. There is no remarkable decrease seen in the number of adult worms, eggs in female schistosomes and eggs in goat feces within 14 months post-infection. Our findings suggest a long duration for infected goat in the transmission of schistosomiasis, and there is no evidence to prove the "self-cure" phenomenon in goat, indicating that goat is an important source of infection for schistosomiasis japonica.