DETECTION AND IDENTIFICATION OF EHRLICHIA SPECIES AMONG DOGS, INCONTACT HUMANS AND TICK VECTORS IN HIMACHAL PRADESH

ANGARIA, SHIVANI

DETECTION AND IDENTIFICATION OF EHRLICHIA SPECIES AMONG DOGS, INCONTACT HUMANS AND TICK VECTORS IN HIMACHAL PRADESH

Date

2019-09-30

Authors

ANGARIA, SHIVANI

Publisher

CSHHPKV Palampur

Abstract

Vector-borne diseases (VBDs) in animals and humans have gained worldwide importance in the climate change scenario. Ehrlichiosis is one of such rickettsial disease. Ehrlichia is an obligate, intra-cytoplasmic, gram-negative bacteria that cause ehrlichiosis in dogs and other vertebrates, transmitted by tick-vectors and occur mainly in the humid and warm regions. These bacteria multiply within the cytoplasm of White Blood Cells (WBCs) of vertebrate hosts and affect various organs. Canine ehrlichiosis is an important tick-borne disease of dogs worldwide and may lead to zoonosis. Till date, not much work has been done on ehrlichiosis, molecular identification and genetic characterization of native strains/species of Ehrlichia prevalent in Himachal Pradesh, therefore, this study was planned to detect the prevalence of Ehrlichia in dogs, tick vectors and humans in different locations of the state. A total of 215 samples were collected including blood samples from dogs (n = 177), blood samples from in-contact humans (n = 24) and ticks collected from the body of the dogs (n = 24). Samples were collected from 105 locations covering 38 tehsils of 9 districts of Himachal Pradesh. All the samples were tested using Ehrlichia genus and three Ehrlichia species (E. canis, E. ewingii and E. chaffeensis) specific PCR tests. 11 (6.2%) of blood samples from dogs were found positive for ehrlichiosis by examination of buffy-coat smears. By PCR tests, out of 177 blood samples of dogs, 107 (60.4%) were found positive for one or more Ehrlichia species. 61 (34.4%) samples were found harboring multiple Ehrlichia species. All the ticks were identified as Rhiphicephalus sanguineus. From ticks, 4.2 per cent samples were found positive, while no human blood sample was found positive. Phylogenetic positions of all the detected Ehrlichia species/strains were determined which were genetically characterized after nucleotide sequencing of partial 16S rRNA gene. It was found that all E. canis, E. platys species/strains were making clusters with earlier reported species/strains from different parts of India and abroad.