Molecular confirmation of Theileria equi Infected clinical cases in Indian Horses

Abstract

Equine piroplasmosis, a tick transmitted haemoprotozoan disease caused by Theileria equi and/or Babesia caballi, poses a serious threat in international movement of infected horses. In India, incidence of clinical cases of T. equi is not uncommon and most of earlier confirmations were based on conventional blood smear examination. Four horses were recorded as acutely infected with T. equi parasite with symptoms of haemoglobinuria, icterus, fever etc. Samples were collected and found positive for T. equi parasites and antibodies upon blood smear examination and EMA-2 ELISA, respectively. T. equi specific EMA-1 gene (Fig. 2) amplification in the DNA of these four clinically infected horses further demonstrated and confirmed this parasite at genome level. In vitro propagation of T. equi by MASP technique was successfully achieved on blood samples collected from three horses, confirming isolation of T. equi parasites. Phylogenetic analyses using 18S rRNA gene inferred the occurrence of three genotypes of T. equi (Indian isolate), which fall in clade ‘A’.