Grahamella legeri sp. n. (Rickettsiales: Bartonellaceae) haemoparasite of Rattus norvegicus (Berkenhout, 1769)

Abstract

It was observed that 25.47% of the Rattus norvegicus examined from the Rio de Janeiro State, Brazil, were infected by Grahamella legeri sp. n. being 53.84% in the rural and 16.25% in the urban zone. The rickettsia found in the blood smears and organ imprints stained by the method of Giemsa was studied morphologically and biologically. The experimental transmission with infected blood was obtained only between individuals of the same species and the enhancement of its virulence by the stress of the host was obtained with Dexa-metazone or by splenectomy. The cultivation of the parasite was attempted in an artificial medium, specific for Grahamella spp. The pathogenicity of the organism was demonstrated. Its systematic position was discussed and it was concluded that it represents a new species of Rickettsiales, Bartonellaceae, so for improperly denominated Grahamella muris Leger, 1913, for which it is proposed the name Grahamella legeri in honor of André Leger.