Haemobartonella is a genus of gram-negative, nonacid-fast, epicellular rickettsial parasites of erythrocytes, currently classified in the family Anaplasmataceae. In stained blood films, H. felis appear as small, blue-staining cocci, rings, and rods. Organisms are approximately 0.5 µm in diameter and attached to the surface of the erythrocytes. Parasitized erythrocytes, lose the normal shape and become spherocytes.
H. felis infection has been transmitted by IP and IV injections and oral administration of infected blood. Saliva and urine are not believed to be infective. Dissemination of infection by blood- sucking arthropods is considered to be primary mode of transmission but has not been established. Haemobartonella can be transmitted from female cats to their new born offspring without presence of arthropods (in utero, during parturition, or via nursing). Iatrogenic transmission can occur by blood transfusion.
The severity of disease varies from mild to life threatening disease. Haemobartonellosis have four phase of disease ( i.e. Preparasitemic, Acute, Recovery, and Carrier phase). Parasites appear in the blood in a cyclic manner.
Some erythrocyte damage may be caused directly by parasites, but immune-mediated injuries appears to be more important. The anemia occurs primarily as a result of extravascular erythrophagocytosis by macrophage in the spleen, live, lungs, and bone marrow.
In my country, cats are often outdoors, and hence, they predispose to a variety of transmissible diseases. Many cats infected with this organism are asymptomatic and others show depression, weakness, anorexia, weight loss, and pale mucous membrane. In 12 outdoor cats, that presented to our clinic with signs of H. felis infections, we can't detect any arthropods infestation. Cats had fluctuant PCV and jaundice.
With attention to the H. felis transmissions, contamination of oral with infected bloods seems to be the major method of transmission. Because we never found any arthropods, and iatrogenic transmission (blood transfusion) wasn't detected. Further more, no maternal transmission were seen because all of cats was matured.
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