Seasonal dynamics of Pneumocystis carinii in the field vole, Microtus agrestis, and in the common shrew, Sorex araneus, in Finland
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.(Received April 30 1998)
(Revised June 23 1998)
(Accepted June 24 1998)
Key Words: Pneumocystis carinii; Microtus agrestis; Sorex araneus; seasonality; transmission.
c1 Corresponding author: Section of Anatomy and Embryology, Faculty of Veterinary Medicine, P.O. Box 57, FIN-00014 Helsinki University, Helsinki, Finland. Tel: +358 9 70849796. Fax: +358 9 70849799. E-mail: Juha.Laakkonen@helsinki.fi