The incidence of helminth parasites in a particular frog population

Abstract

1. Frogs were collected from a single area in the West Riding of Yorkshire and examined for adult helminth parasites. The following species were found:Polystoma integerrimum, Gorgoderina vitelliloba, Haplometra cylindracea, Dolichosaccus rastellus, Rhabdias bufonis, Cosmocerca ornata, Oswaldocruzia filiformis, Aplectana acuminataandAcanthocephalus ranae.2. The seasonal incidence and intensity of infection was studied by monthly examinations of 2413 frogs over a period of 4 years. The highest incidence of parasitization by helminths occurred in the autumn. In general, when the incidence was high, the intensity of infection was also high.3. The incidence of infection was generally higher in male than in female frogs. This effect of the host's sex was much more marked immediately before the breeding season than at any other time of the year.4. Possible reasons for these variations in levels of infection are discussed.