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Subject: Veterinary Parasitology × Author: GATCHANDA SHRAVAN KUMAR × End date: 2023 × Start date: 2020 × Type: Thesis ×
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    ThesisItemOpen Access
    MOLECULAR DETECTION OF HAEMOPROTOZOAN AND HAEMORICKETTSIAL ORGANISMS IN COMMUNITY OWNED DOGS OF KERALA
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES POOKODE, 2022-02-11) GATCHANDA SHRAVAN KUMAR; Anju Varghese
    India's diverse climatic zones are ideal for a wide range of vectors and pathogens. Most of the community/stray dogs suffers from a variety of diseases due to malnutrition and lack of basic health care. Stray dogs are thought to be suitable reservoirs of several zoonotic parasites. The objective of the present study was to detect haemoprotozoans and haemorickettsial organisms from community owned dogs of Kerala. A total of (n=150) peripheral blood smears and whole blood samples were collected from community owned dogs from different zones of Kerala. The peripheral blood smear examination revealed prevalence of 21.33 per cent and 8 per cent for Babesia gibsoni and B. vogeli infection by microscopy. None of the blood smears were positive for any other haemoparasites. The genomic DNA was extracted from all the blood samples and used as a template for detection of haemoprotozoan and haemeorickettsial organisms. The B. gibsoni genus specific primer targeting 18S rRNA showed an amplicon size of ~1655 bp length in 61 samples (40.67 per cent) by primary PCR. The PCR product of primary PCR was utilized as a template for nested PCR using a set of internal primers and amplified a ~308 bp fragment of 18S rRNA gene in 87 samples (58 per cent). The polymerase chain reaction targeting B. gibsoni TRAP gene showed an amplification at ~855 bp size in 90 samples (60 per cent). The PCR amplification of B. vogeli and Hepatozoon canis targeting 18S rRNA gene showed an amplicon size of ~590 bp length in 59 samples (39.33 per cent) and 666 bp length in 42 samples (28 per cent) respectively. Trypanosoma evansi was positive in 41 samples (27.33 per cent) using T. evansi specific RoTat 1.2 gene giving out a product size of ~205 bp. Only a single sample showed PCR amplification for Ehrlichia canis VirB9 and gp-200 genes with amplicon sizes of ~380 bp and ~1286 bp respectively. Amplification at ~678 bp length by PCR targeting 16S rRNA gene of Aanaplasma platys was obtained only in one sample. Among canine vector borne diseases in community owned dogs of Kerala, B. gibsoni was highly prevalent followed by B. vogeli, H. canis, T. evansi, E. canis and A. platys. Mixed infection of B. gibsoni with other haemoprotozoans and haemorickettsiales was recorded from all zones of Kerala with a high co-infection of B. gibsoni and B. vogeli (32.67 per cent) followed by B. gibsoni and H. canis (18 per cent). Selected amplicons of B. gibsoni, B. vogeli, H. canis, T. evansi, E. canis and A. platys were sequenced. The phylogenetic analysis based on 18S rRNA gene of B. gibsoni and H. canis, 16S rRNA gene of A. platys and VirB9 and gp-200 gene of E. canis does not showed any genetic diversity. However, the phylogenetic analysis of TRAP gene of B. gibsoni sequences indicated that B. gibsoni field isolates of Kerala in the present study formed a single clade with other Indian and Bangladesh isolates and separated away from East Asian countries. Thus, the isolates of B. gibsoni from Indian subcontinent are genetically unique compared to other Asian isolates showing a maximum genetic diversity. The phylogenetic analysis based on 18S rRNA gene of B. vogeli indicated that the B. vogeli isolates circulating in pet and community owned dogs of Kerala and other parts of India are genetically different from other Babesia spp. isolates from other countries, indicating two lineages of B. vogeli in the world. The phylogenetic analysis of T. evansi using RoTat 1.2 gene showed that the isolates from dogs formed a monophyletic clade with the T. evansi isolates from Buffalo of India and Indonesia. The high nucleotide variation with in our sequences may be the possible attributes for showing the high genetic diversity within T. evansi population from other countries and different hosts. Data from the current study suggest that the tick- borne pathogens are highly prevalent among community owned dogs of Kerala. The hot and humid climatic conditions of Kerala is congenial for the survival of ticks and tick- borne pathogens. The difference in prevalence in the present study from community owned dogs and pet dogs could be due to area of sample collection, sample size, the type of dogs screened and selection of clinically suspected samples from pet dogs. In the present study, blood samples have been collected from community owned dogs from Animal Birth Control Centres (ABCs) and not from clinically suspected hospital cases for different haemoprotozoan organisms. The 129 present study formed the first and foremost prevalent study of haemoparasites in community owned dogs of Kerala.