Seasonal and age distributions of Babesia, Hepatozoon, Trypanosoma and Grahamella species in Clethrionomys glareolus and Apodemus sylvaticus populations.

Four common blood parasites belonging to the genera Babesia, Hepatozoon, Trypanosoma and Grahamella were detected in sympatric populations of Clethrionomys glareolus and Apodemus sylvaticus. Seasonal changes in the abundance of hosts and parasites were monitored in a longitudinal field survey for 18 months. All parasites in both hosts showed similar seasonal patterns with most transmission occurring in summer and autumn and ceasing in winter. Amongst aged subsets of each host population, Hepatozoon and Grahamella spp. were primarily parasites of young animals whereas Babesia and Trypanosoma spp. generally infected older hosts. Data from the aged subsets were also used to estimate values for the basic reproductive rate, R0, for each parasite. In C. glareolus, R0 = 2.0 for B. microti, 2.6 for H. erhardovae, 1.7 for T. evotomys and 2.8 for Grahamella sp. In A. sylvaticus R0 = 2.2 for Grahamella sp. These estimates are probably representative only for summer and autumn of each year.