The morphology and biology of Trypanosoma (Herpetosoma) evotomys of the bank-vole, Clethrionomys glareolus

Abstract

The morphology and biology of the various stages of the life-cycle of Trypanosoma evotomys has been studied in laboratory bred vertebrate and invertebrate hosts. The morphology of T. evotomys in the blood of the bank-vole, Clethrionomys glareolus, is typical of that of a trypanosome of the subgenus Herpetosoma, but the shape and size of the trypanosome in C. glareolus is more variable during the reproductive phase of the infection than in the adult phase. The duration of the infection of T. evotomys in C. glareolus varies from 22 to 31 days in experimental infections and the incubation period of the infection initiated by metatrypanosomes is 5–6 days. The peak of the parasitaemia varied from 15000 to 55000 parasites per mm3 of blood. The reproductive stages of T. evotomys are found in the spleen and lymphoid tissue (appendix) of the bank-vole, and reproduction is by equal, binary or multiple fission in the amastigote stage. T. evotomys was not transmissible to M. agrestis, mice or rats. Cyclical development of T. evotomys took place in the flea, Nosopsyllus fasciatus, and metatrypanosomes developed in the intestine of the flea. No intracellular forms of T. evotomys were found in the mid-gut of the flea.The encouragement, help and advice of Dr P. Tate is gratefully acknowledged. Financial support was received from the Agricultural Research Council to whom thanks are also due.