First report on molecular prevalence and identification of Anaplasma platys in dogs in Khon Kaen, Thailand

Abstract

Background and Aim: Anaplasma platys is a blood parasite that infects platelets, causing thrombocytopenia. Rhipicephalus sanguineus ticks are believed to transmit A. platys. To identify A. platys, nested polymerase chain reaction (PCR) has proven to be an effective diagnostic tool. In this study, the molecular prevalence of A. platys infection in dogs was investigated for the 1st time in the Khon Kaen region of Thailand. The association between risk factors and A. platys infection was also evaluated. Materials and Methods: A total of 130 blood samples were collected from dogs in Khon Kaen, Thailand. DNA from the samples was extracted and nested PCR was applied for molecular analysis. Platelet count and packed cell volume (PCV) levels were measured. Platelet counts were categorized into four grades: Non-thrombocytopenia (platelets >200,000 cells/μL), mild thrombocytopenia (platelets 150,000-200,000 cells/μL), moderate thrombocytopenia (platelets 100,000-150,000 cells/μL), and severe thrombocytopenia (platelets <100,000 cells/μL). Four categories for PCV levels of >37%, 30-37%, 20-29%, and <20% were defined as no anemia, mild anemia, moderate anemia, and severe anemia, respectively. DNA sequencing was analyzed using BTSeq™ (Barcode-Tagged Sequencing; CELEMICS, Seoul, South Korea) for similarity index. Results: Among the 130 samples, 9 (6.9%) were positive for A. platys infection. There was an association between low platelet count and infection (p<0.05). PCV level was also associated with A. platys infection (p<0.05). DNA sequencing results of the nine positive samples showed similarity to known sequences of A. platys with 99.36-100% nucleotide identity. These results suggested low genetic diversity in A. platys infecting dogs in the Khon Kaen area. Conclusion: By amplifying 16S rRNA, A. platys infection was detected in the blood of Thai dogs. Further work should be performed to identify risk factors potentially associated with A. platys infection in dogs in Khon Kaen. Other related factors should also be considered, such as location and breeding, as well as the environmental characteristics of each locality. In addition, sampling a larger number of animals may reveal predictors for the positivity of A. platys in dogs in this region.