Identification of Ehrlichia spp in canines in Thailand.

Canine ehrlichiosis is an endemic parasitic disease widely found in Thailand. The causative microorganism is tick-borne Ehrlichia spp, an obligate intracellular rickettsia residing in leukocytes. Ehrlichia spp in morulae-positive canine blood samples were identified using polymerase chain reaction amplification and direct sequencing of Ehrlichia spp. 16S rDNA 396 bp fragment and 36 of 59 were positive for E. canis. E. chaffeensis and E. ewingii were not detected. Sequencing alignment and phylogenetic analysis showed that 16S rDNA sequences of E. canis strains are 99.1-100% identical among E. canis strains from different countries worldwide. Further studies are required in order to determine new target sequence for genotyping of E. canis strains in the dog population in Thailand.