Epidemiologic and clinical surveys in dogs infected with Babesia gibsoni in South Korea.

Clinically diagnosed cases of Babesia gibsoni infection in dogs were evaluated on the basis of polymerase chain reaction (PCR) results and nucleotide sequences of the 18S rRNA gene. Twenty-nine of 117 submitted dogs were PCR positive. The breed of dogs infected with B. gibsoni varied; however, pit bull terriers were the breed most often infected. The infection rate was higher in densely populated regions and in male dogs. Young dogs (age < 3 years) were more sensitive to B. gibsoni infection, and 6 out of the 29 infected dogs had a history of tick exposure. The clinical signs observed during physical examination were related to canine babesiosis, and many dogs showed symptoms similar to those associated with anemia. The results of hematologic analysis revealed severe hemolytic anemia and thrombocytopenia in the infected dogs. However, the blood smears of 29 infected dogs showed very low levels of parasitemia. Nucleotide sequencing of the PCR products revealed that the 18S rRNA gene sequences of B. gibsoni in South Korea were very close to those reported in Spain, Japan, and the United States.