Age-dependent infectivity of orally transferred juvenile Fasciola hepatica

Juvenile Fasciola hepatica is infective when administered orally. To determ ine whether the age of juveniles is a factor in infectivity by oral transfe r, experimental mice were challenged orally with immature F. hepatica that had been grown in donor mice for 12, 14, 16, and 18 days. Experimental mice were examined for infections 12-16 days after the oral transfers. The infe ction success in experimental mice decreased with the age of juveniles. The worm recovery also decreased according to the ape of juveniles. None of th e juveniles was infective when grown for longer than ii days. Once infected , orally transferred worms continued to grow. Juvenile age was a significan t factor in determining the infectivity of orally transferred juvenile F. h epatica.