[Studies of the ecology of some blood protozoa of wild small mammals in North Germany (author's transl)].

In 1977 and 1978, 696 small mammals of 9 different species were surveyed for protozoal blood parasites. The following parasites were found: Hepatozoon sylvatici in Apodemus flavicollis, H. erhardovae and Trypanosoma evotomys in Clethrionomys glareolus, T. microti and Babesia microti in Microtus agrestis and T. croicidurae in Crocidura russula. H. erhardovae showed regularly high infection-rates (more than 70%) during all the years in 1977 and 1978. H. sylvatici was found only in 5.6% of the yellow-necked mice from March to October. T. microti and T. evotomys were predominately found in the time from July to October. The high infection-rates of the bank vole with B. microti from January to March and July to August indicate a bimodal type of seasonal dynamic. Under natural conditions M. agrestis was the only host for B. microti. Nymphs of the tick Ixodes ricinus were found to be able to transmit B. microti to Syrian golden hamsters (Mesocricetus auratus) in the laboratory.