Seasonal dynamics of Pneumocystis carinii in the field
vole, Microtus agrestis, and in the common shrew, Sorex araneus,
were investigated in southern and central Finland by microscopical examination
of methenamine silver-stained tissue
sections. In both host species at both localities the number of P.
carinii cyst forms was highest in late autumn (November).
In S. araneus, prevalence was higher than in M. agrestis
during all seasons. None of the animals was heavily infected or
apparently ill, and neither species showed any extrapulmonary dissemination.
In this study covering an increase phase and
4 peak host-density phases of the vole cycle, the occurrence of P.
carinii seemed to be related to the population density
of M. agrestis.