Effects of praziquantel and metrifonate on Schistosoma bovis infections in Sudanese cattle.

Twelve nine-month-old zebu calves were each experimentally infected with 10,000 Schistosoma bovis cercariae. Four were treated orally with 20 mg/kg praziquantel at weeks 9 and 14 after infection, and four were treated orally three times with metrifonate at week 11 (25 mg/kg) and again at week 14 (50 mg/kg). Praziquantel proved to be highly effective, reducing faecal egg counts near to zero; the mean live worm count in the treated calves at week 16 was only 32, compared to 2850 in the untreated group, a reduction of 98.9 per cent. In contrast, metrifonate treatment caused only a very short-lived, partial reduction in faecal egg counts, and no reduction in live worm counts.