Sunday, February 9, 2014

Vector Borne Diseases Part 6: Babesia

Babesia are another genus of protozoa that infect dogs via tick bites.  In addition to tick bites females can spread the organism to puppies via the placenta and direct dog to dog transmission is possible via bite wounds or blood transfusion.  Once they gain access to the bloodstream the Babesia set up shop in the red blood cells.  The body, of course, notices the intruders and sets out to destroy the infected cells  Sometimes the body gets carried away with this and begins destroying uninfected cells as well creating both a direct and immune-mediated hemolytic (destruction of red cells) anemia.  Greyhounds, pit bull terriers, dogs with previous splenectomies, and those with an already compromised immune system (aka dogs undergoing chemotherapy) are most commonly affected.

Most common signs are those that go along with anemia-pale gums, lethargy, weakness, anorexia, jaundice, etc.  Other signs can include fever, enlarged spleen and lymph nodes, elevated liver enzymes and renal failure.  In addition to the anemia the inflammation associated with this disease can cause platelet counts to drop leading to bleeding disorders.

Diagnosis can be make via visualization of the organism in the bloodstream, history of ticks and compatible clinical signs and by sending off for a PCR test.

Treatment often involves addressing any shock or hypovolemia with fluid therapy, possible blood transfusion pending the degree of anemia and clearing of the organism itself.  There are several suggested protocols for this but currently the treatment of choice is azithromycin and atovaquone.  In addition immune suppressive drugs are sometimes needed to stop the red cell destruction.

Babesia is present worldwide and any dog can become infected.  Prevention is aimed at tick control, reducing bite incidences, screening blood donors and not breeding infected females.  Ticks must feed for greater than 24 hours to transmit the disease so daily checks and use of routine tick control products are helpful.

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