Molecular identification of babesiosis in stray dog at Chittagong Metropolitan Area

Abstract

An epidemiological study of babesiosis in stray dogs was conducted at Chittagong Metropolitan area, Bangladesh, for six months. Blood samples of 130 stray dogs were collected from nine randomly selected locations along with the information of age and sex. Blood samples were initially examined by Giemsa's stained blood smear method. DNA was extracted from microscopy positive blood samples and Babesia spp were confirmed by amplifying 18S rRNA gene. The prevalence was determined 6.92% in microscopic technique and the percentages of PCR positive samples from the microscopy positive samples were 66.67% (6 out of 9). The highest prevalence of babesiosis was found in Alankar (16.67%) compared to other areas. Significantly higher frequency of babesiosis was found in adult dog than younger (p<0.05). Again, Babesia infection was common in male (11.94%) than female (1.59%) and were statistically significant (p<0.05). Furthermore, we sought to develop a seminested PCR to detect and differentiate Babesia gibsoni (Asia genotype), B. canis subsp. vogeli, B. canis subsp. canis and B. canis subsp. rossi DNA in canine blood samples. An outer primer pair was designed to amplify a 340 bp fragment of the 18S rRNA genes in the seminested primary reaction. Then specific internal primers were designed for B. gibsoni (Asian type) (BgibAsia-F) and B. canis subsp. canis (BCC-F) that were paired with the outer reverse primer in the seminested secondary reaction to amplify 185 bp and 198 bp respectively. Based on seminested PCR and sequencing of the PCR products, all parasitic isolates were identified as Babesia gibsoni (Asian type) and B. canis subsp. canis. These results recommended that Babesia gibsoni (Asian type) and B. canis subsp. canis parasites are widespread in stray dog in Chittagong Metropolitan area, Bangladesh. Further investigations are required to clarify the origin, distribution, vector and pathogenesis of these parasites tracking in dogs in Bangladesh.