[Estimation of the infestation of mollusks by protostrongylids: parameters used and their interrelation].

Several parameters were utilized in order to estimate the infection of Mollusc by Protostrongylids. It was demonstrated that the prevalence, the number of larvae per snail and the aggregation were linked either in experimental infections or natural ones. In the former, prevalence was more related to rate of infection than to the aggregation. On the contrary the prevalence was mostly depending on overdispersion in field infections.