The effect of density of first-stage larvae of Elaphostrongylus rangiferi on the infection rate in the snail intermediate host.

The relationship between the density of 1st-stage larvae of Elaphostrongylus rangiferi on the infection rate into the gastropod intermediate host, Arianta arbustorum, was studied experimentally. Within a range of densities between 30 and 1100 larvae/cm2 the experimental data gave a good fit to the conventional epidemiological assumption of direct proportionality between the net infection rate and the density of infective stages. The instantaneous rate of infection was estimated to be about 1 x 10(-3)/larvae/snail/2 h. At higher densities (greater than 1100 larvae/cm2) the instantaneous rate of infection showed a density-dependent decline.