Published online by Cambridge University Press: 06 April 2009
Nine out of thirty-three specimens of the common shrew Sorex araneus, caught at Rosta in north Norway in August 1953, were found to be infected with Grahamella (Rickettsiales). Nine specimens of Clethrionomys rutilus, nine of Microtus oeconomus ratticeps and one of M. agrestis, caught at the same time and place, were found to be free of Grahamella. No other blood parasites were found in any of the animals examined.
Records by other authors of Grahamella in a variety of hosts are reviewed. The parasite is known to occur in mammalian hosts only: identifications of it in non-mammalian hosts can be discarded. Host specificity, tacitly assumed by most authors, is not proven, and therefore most of the specific names bestowed on Grahamella in different hosts are of doubtful validity. The morphology of the parasite varies little from host to host; and there is little evidence to show that its pathogenic effect on any host is serious. Grahamella has been cultured by a few authors: variations in characters of these cultures may be more reliable criteria for recognition of different species of Grahamella.
These small mammals were collected while I was a member of the University of Edinburgh Expedition to Arctic Norway, 1953. I wish to thank all who were concerned, in particular Dr D. M. Steven, with whom I did the trapping. The rest of the work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I also wish to thank Dr P. Tate for his advice and his criticisms of the manuscript.