Tick and tick-borne parasitic diseases of dog prevalent in and around Guwahati, Assam
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Date
2022
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College of Veterinary Science, Assam Agricultural University, Khanapara Campus
Abstract
The study was conducted to record the prevalence of ticks on dog and haemoparasites borne by them. Molecular identification and characterization of the prevalent tick species was also done in order to know their taxonomic status and evolutionary relationship. The study was conducted from March, 2021 to February, 2022. 1440 dogs were examined for the presence of ticks on their body. Out of 1440 dogs, 986 (68.47%) were found to be infested with ticks. 504 (35.00%) ticks were identified as Rhipicephalus sanguineus, 260 (18.06%) were identified as Haemaphysalis bispinosa and 222 (15.42%) were found to be mixed infestation. The highest prevalence of R. sanguineus ticks during August (61%) and the lowest during February and December (25%). Highest prevalence of H. bispinosa was recorded during August (26.67%) and the lowest during February and January (10.00%). Mixed infestation was highest during August (35.0%) and lowest during December (5.0%). The month-wise prevalence was found to be non-significant by statistical analysis (P value: 0.964948). The highest prevalence of ticks was recorded during the monsoon (95.42%) followed by the post-monsoon and the lowest during winter (37.5%). Statistically season has no significant influence on the prevalence of ticks on dogs (P value: 0.6541). The highest percentage of dogs infested with Rhipicephalus and Hemaphysalis tick at the age of 2-3 years (53.49%) and 6 month to 1 year (18.24%) respectively and lowest in 9-10 years (0%). The prevalence of ticks was significantly influenced by the age of dogs (P: 2.28695E-08). Labrador breed of dogs (98.23%) were found to be most infested by ticks followed by Local/mongrel (91.30%) and the least in St. Bernard (7.14%). The breeds of dog were found to be significantly influence the prevalence of ticks (P: 2.1666E-17). The female dogs showed higher prevalence of ticks (52.54%) than their male counterparts (47.46%). The most preferred site of attachment of the ticks on the dog‟s body was ears (28.39%) followed by head (18.56%) and paws/toes (17.64%). Morphological study of both the prevalent tick species were done and characteristic diagnostic features were figured out with photograph. Molecular identification and characterization of prevalent tick species were done by amplification of the 16S rRNA gene by PCR. Phylogenetic analyses by neighbor joining method were performed and the pair wise distance of 16S rRNA were done with MEGA X software. The pair wise distance study revealed that the R. sanguineus strain As/AAU/RS-01 was found to be 100% identical to the isolates of tropical lineages and is 6.4-7.5% divergent with the isolates of temperate lineages. H. bispinosa strain AS/AAU/HB-01 formed the clade with other isolates of H. bispinosa. The closely related isolates of AS/AAU/HB-01 were observed to be Chipahikhola isolate, Itanagar isolate and Arunachal pradesh isolates. The pair wise distance of AS/AAU/HB-01 showed divergence of 0-3.6% with other isolates of H. bispinosa and with other species of Haemaphysalis was between 9.3-14%. 4119 numbers of Giemsa‟s stained thin blood smears were examined under the light microscope for presence of tick-borne hemoparasites. The prevalent of five tick borne haemoparasites in dogs were recorded were Babesia gibsoni (10.34%), Babesia canis (0.92%), Hepatozoon canis (0.39%), Anaplasma (Ehrlichia) platys (0.12%) and Ehrlichia canis (0.22%). Out of 526 positive blood samples, 100 randomly selected positive samples were confirmed with PCR by amplification of 18S rRNA gene for (B. gibsoni, B. canis, H.canis) and 16S rRNA gene for (A. platys and E. canis) and found that PCR shows more sensitivity than light microscopy. Overall prevalence of tick borne haemoparasites, irrespective of season, breed, age and sex is recorded to be highest in the month of July (16.92%) followed by September (16.19%) and lowest in the month of February (4.18%).The highest prevalence of Babesia gibsoni was noticed in Labrador breed (12.93%) followed
by local/mongrel dogs (11.53%) while Babesia canis was mostly encountered in Lhasa apso dogs (2.63%) followed by Boxer breed (2.38%) of dogs. Similarly, Pomeranian breed was found to be mostly infected by Hepatozoon canis (1.96%) followed by Doberman (1.55%) dogs. On the other hand, the rickettsial organism Anaplasma platys affect mostly Shitzu (3.85%) dogs followed by Dalmatian breed of dog (2.56%) and Ehrlichia canis was found to affect mostly Lhasa apso (2.63%) followed by Boxer dogs (2.38%). It has been noticed that out of all 18 breeds of dog in the present study, Labrador breed of dog is found to infect most by different haemoparasites followed by local/ mongrel dogs. Female dogs were recorded to be more affected than the male dogs. Statistical analysis revealed that sex of dog has significant influence on the prevalence of tick-borne hemoparasites (P: 0.040134). The highest prevalence of hemoparasites was seen in 1-2 years of age (17.70%) followed by <1 year (16.32%) and 2-3 years (14.88%) of age. The lowest prevalence was observed in 11-12 years of age (2.86%) and mixed infection of Babesia canis and Babesia gibsoni is found to be highest of all other combination of infection.