The pattern of mortality in mice experimentally infected with Fasciola hepatica

The extent and pattern of mortality of mice exposed to low levels of F. hepatica were determined for a 56-day period. Mice were exposed to 1, 2, 3, 4 or 6 metacercariae per mouse with emphasis placed on one cyst infections. Eighty per cent of all deaths occurred between days 27 and 35 post exposure with the mean death day for all being from 31 to 34 days postexposure. The mortality followed a statistically predictable pattern with the use of one-cyst infections as an extrapolation point. As the dose increased, the percentage mortality increased as a simple multiple of probabilities indicating the absence of synergism or antagonism in producing death when more than one parasite was present. Relatively low levels of infection in mice reliably produced high mortality within a limited time period and, thus, mortality could be used as a parameter of infection for studies with a variety of aims.