Introduction

Babesia sp. are protozoal organisms that parasitize erythrocytes, causing anemia in the host. Many different species exist with varying host specificity (5). B. canis and B. gibsoni are two organisms commonly known to infect dogs. Both organisms have Ixodid tick vectors and are found throughout Asia, Africa, Europe, the Middle East, and North America, with B. canis being more prevalent (11). Infection by B. gibsoni is increasing in frequency, particularly in North America, although no specific species of ticks in this region have been proven to transmit the disease. However, Rhipicephalus sanguineus and Dermacentor variabilis are believed to be potential vectors of disease (2). There also is evidence that some direct animal-to-animal transmission may occur, as when an infected dog with oral abrasions bites a naïve dog. Kennel settings with poor tick surveillance and control are at a higher risk for housed animals to develop babesiosis (2).

Babesiosis has been classically diagnosed by demonstrating intraerythrocytic trophozoites on a blood smear. Giemsa, Romanowsky, Field’s, and modified Wright’s stains are suitable for this purpose. B. canis generally appears as a paired, piriform figure measuring 5 x 2-3 micrometers (Fig. 1). B. gibsoni is usually smaller (measuring 1.9 x 1.2 micrometers), singular, and signet ring shaped (Fig. 2). Sampling of blood from a capillary bed (from the ear, for instance) yields more diagnostic smears than sampling blood from a larger vein (8). Isolation of infected erythrocytes with a Percoll gradient can be used to enhance the recovery and identification of parasitized erythrocytes (4). The degree of parasitemia is very low with B. canis, but may range from 2% to 6% (or greater) of the erythrocyte population with B. gibsoni (7).

Treatment and Prevention
Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.

Current chemotherapeutic agents used to treat canine babesiosis are incapable of completely eliminating the disease; they only are capable of limiting mortality and the severity of clinical signs (2). Two injections of Imidocarb diproprionate at 5.0 to 6.6 mg/kg given subcutaneously or intramuscularly at an interval of 2 to 3 weeks are reputed to be effective (8). Another possible treatment is a single intramuscular injection of Dimenazene aceturate at a dosage of 5 mg/kg (2). For a more exhaustive list of potential antiparasitic drugs, consult table 77-3 in Greene’s Infectious Diseases of the Dog and Cat (11). Supportive therapy such as intravenous fluids and blood transfusions should be employed when necessary.

Owners should be aware that animals that have survived babesiosis remain subclinically infected. These dogs may suffer a relapse of disease in the future or serve as point sources for the further spread of disease in a given area (2). In addition, dogs that have recovered from babesiosis should never be used as donors for blood transfusions because the recipients may develop the disease.

Currently, an effective vaccine is not commercially available to protect dogs against babesiosis. The previously mentioned vaccine against the soluble plasma antigen produced by Babesia organisms limits the clinical signs of disease, but does not affect the development of parasitemia. This vaccine is not available in the United States (11).

source :

http://www.vet.uga.edu/vpp/clerk/Cleveland/

Ads: Get a free $250 Petsmart gift card! - For US Only

.