Comprehensive study of ticks and tick-borne diseases in dogs in Nepal: Molecular identification, risk analysis and hematological alterations

Background Ticks are responsible for the transmission of various viral, bacterial, and protozoal pathogens through their mouthparts while feeding on the blood of the host. Owing to the increasing trend of tick-borne diseases, they are considered major emerging public health issues throughout the globe. In South Asia, the major important canine tick-borne pathogens are Babesia spp., Hepatozoon canis , Ehrlichia canis , Anaplasma platys , and Borrelia burgdorferi. Among various diagnostic tests, molecular techniques are considered the gold standard for the detection of tick-borne diseases. A total of 341 blood samples from each individual dog were collected from Kathmandu, Pokhara, and Chitwan, Nepal. The collected blood samples were subjected to hematological analysis, DNA extraction, and conventional polymerase chain reaction to detect the presence of tick-borne pathogens. Additionally, a total of 219 ticks were collected from the sampled dogs and identified via morphometry. Results PCR assays revealed four tick-borne pathogens, Babesia spp., Ehrlichia canis , Hepatozoon canis , and Anaplasma platys, with prevalence rates of 26.09%, 5.87%, 3.52%, and 2.93%, respectively, and an overall prevalence of 31.09% (95% CI: 26.27--36.34%). However, this study could not identify the prevalence of Borrelia burgdoferi . During the hematological analysis, anemia and thrombocytopenia in the sampled dogs were significantly associated with the presence of Babesia spp. (p<0.01 and p<0.05, respectively), lymphocytosis was significantly associated with hepatoma canis (p<0.001), and thrombocytopenia was significantly associated with Ehrlichia canis (p<0.05). Among the ticks infesting dogs at the study sites, the Rhiphicephalus genus was the most prevalent, followed by Hemaphysalis and Dermacentor, with an overall tick infestation rate of 27.86%. Geographic location, type of dog (stray or pet), and body condition score were determined as potential risk factors by multiple logistic regression analysis (OR= 0.40, 2.16, 0.73; p<0.01, p<0.05, p<0.05,respectively) for the presence of canine tick-borne pathogens. Conclusions This study is among the first to investigate the prevalence of canine tick-borne pathogens in both pet and stray dogs in Nepal via molecular testing, which revealed the prevalence of at least four canine tick-borne pathogens and three genera of ticks present in the canine population of Nepal. This highlights the importance of robust treatment, control and preventive measures to mitigate the transmission of these pathogens.