Abstract
Haemobartonella canis was observed in the peripheral blood of both intact and splenectomized mongrel dogs inoculated intravenously with Babesia gibsoni derived from a dog affected naturally in Nagasaki City. It was detected on the erythrocytes of 13 experimental dogs, except 7 dogs inoculated with the Babesia strain only for passage and not examined hematologically. The incubation period of H. canis infection was between 3 and 8 days, with 4.7 days on the average, after inoculation. H. canis appeared on erythrocytes on the same day with or a few days earlier than B. gibsoni. Its organisms attached to the surface of the erythrocyte singly, in a raw, or in a cluster, and reddishpurple in color on Giemsa-stained films (Figs. 3-5). In scanning electron microscopy, erythrocytes parasitized with many H. canis were deformed markedly, showing invaginations of the surface membranes. Coccoid, bacillary or doughnut-shaped organisms about 0.2-0.6 μm in diameter were located in grooves (Figs. 6 and 7). In transmission electron microscopy, the organisms were bound with a single trilaminar unit-membrane and packed with much dense granular substance (Fig. 8). This is the first report on the existence of H. canis in Japan.
