D303 - Babesia spp.

Description:

Babesiosis is a disease of worldwide significance caused by tick-born hematozoan organisms of the genus Babesia. Babesia canis and Babesia gibsoni are the two species capable of natural infection in the dog, whereas Babesia felis, Babesia cati, Babesia herpailuri, and Babesia pantherae have been reported in cats. Transmission of babesias is by the bite of infected ixodid ticks. The adult female tick is most important in transmission, but all stages of the tick are likely to be infected. Once in the host, Babesia spp. attach to the erytrocyte membrane and are engulfed endocytosis. Once in the erytrocyte, the red blood cell membrane that surrounds the parasite disintegrates, and all subsequent stages are in direct contact with the host cell cytoplasm. Babesiosis in dogs may follow hyperacute, acute, chronic, or subclinical courses. Most infected dogs in the United States and Canada are subclinical carriers. Acute disease characterized by fever, lethargy, and acute anemia is the most common clinical syndrome, whereas the presentation characterized by shock and extensive tissue damage is rare. Acute signs of infection are typical of Babesia gibsoni and the more virulent strain of Babesia canis. The hyperacute presentation, although uncommon, can have devastating consequences. It is characterized by hypotensive shock, hypoxia, extensive tissue damage, and vascular stasis. A high percentage of dogs with this form of babesiosis die despite therapy. Kennel dogs with heavy tick exposure can be infected at a high rate with multiple, potentially zoonotic, various tick-borne pathogens such as Ehrlichia, Bartonella, Rickettsia, and Babesia species.
Cats with naturally occurring babesiosis usually show lethargy, anorexia, weakness, rough hair coat, or diarrhea. Fever and icterus are rarely observed. Chronic anemia can be severe and is the underlying reason for the clinical signs. Cats usually adapt to the anemia and may have only mild clinical signs until they experience the stress of a physical examination or diagnostic evaluation.

Diagnosis:

New methods for the diagnosis of babesiosis are needed because of the inherent limitations of traditional methods. Parasites are often missed on blood smear examination when animals with babesiosis first seek medical care, because usually less than 1% of erythrocytes are parasitized early in the course of the illness. Antibody testing is useful for the confirmation of babesiosis, but it also may yield a negative result in the early phase of illness. Dogs infected with Babesia gibsoni may have false-positive serologic test results for Toxoplasma gondii and Neospora caninum as well as for Babesia canis. PCR test should be used when acute babesiosis is considered and blood smear results are equivocal or negative.

Sample:

Whole blood (3 ml) in a lavender top (EDTA) tube.

Special Handling:

Store blood and tissue samples at 4°C until pick up or shipment.

Test Code:

D303

1. Kordick et al. (1999) Coinfection with multiple tick-borne pathogens in a Walker Hound kennel in North Carolina. J. Clin. Microbiol. 37 : 2631-2638.
2. Yamane et al. (1993) Evaluation of the indirect fluorescent antibody test for diagnosis of Babesia gibsoni in dogs. Am. J. Vet. Res. 54:1579-1584.