Babesiosis [ba-be-si-o-sis] can affect pets as well as livestock, wildlife and humans. It is caused by the Babesia genus. These organisms are pear-shaped protozoans which live in the red blood cells of mammals. They are similar to the protozoans that cause malaria and sleeping sickness and are sometimes referred to as “piroplasms”.
In addition to transmission via infected ticks, Babesiosis can also be spread iatrogenically by blood-contaminated needles or surgical instruments and through contaminated blood transfusions. Fighting between dogs may also result in transmission of certain Babesia species. At the present time, there is no evidence of transmission via other vectors.
Following ingestation by the tick, gamogony and sporogony (stages in the sexual reproduction of Babesia protozoa) occur within the gut of the tick, resulting in production of sporozoites (cells that infect a new host). Once inoculated into the new host, the Babesia sporozoites invade the erythrocytes, where they multiply asexually by binary fission. The resultant merozoites (daughter cells) rupture the red blood cells and go on to invade additional erythrocytes.
Babesia species found in companion animals include:
In dogs – Babesia canis and B. gibsonis
In cats – B. felis and B. cati
In horses – B. equi and B. caballi
The spectrum of disease ranges from asymptomatic to the sudden onset of acute disease, which can be fatal. Symptoms generally result from the destruction of red-blood cells with the simultaneous release of haemoglobin and organisms into the blood stream. Splenectomy and immunosuppression exacerbate both parasitaemia and clinical disease from infections with Babesia species.
Animals that have survived Babesiosis remain subclinically infected. They may suffer a relapse in the future and can be a source for further spread of disease. Animals that have survived Babesiosis should NEVER be used as donors for blood transfusions because the recipients may develop the disease.
For details on the signs and symptoms, diagnostic techniques and treatment regimes in dogs, cats and horses, please follow the links to the right.