# The first molecular detection of equine piroplasmosis in Vietnam and genetic characterization of three co-circulating genotypes of Theileria equi

## TL;DR

This study reports the first molecular detection of equine piroplasmosis in Vietnam and identifies three genotypes of Theileria equi.

## Contribution

The first molecular detection and genetic characterization of Theileria equi in Vietnam.

## Key findings

- T. equi was detected in 15.58% of sampled horses in northern Vietnam.
- Three genotypes (A, C, and E) of T. equi were identified through phylogenetic analysis.
- Babesia caballi was not detected in any of the samples.

## Abstract

Equine piroplasmosis, caused by Theileria equi, T. haneyi and Babesia caballi, significantly impacts on the veterinary and economic aspects of the global horse industry. However, many countries, including Vietnam, have not yet conducted epidemiological surveys to determine the prevalence of these haemoparasites. This study aimed to detect T. equi and/or B. caballi infections in horses and to identify their genotypes. Blood samples were collected from 154 apparently healthy horses in eight districts of Hanoi, Thai Nguyen, and Son La provinces located in the northern part of the country. Twenty-four horses (15.58%, 95%CI: 10.70–22.14%) were found to be infected with T. equi across six districts. Babesia caballi was not detected. No significant association was found between gender, host age, and the number of infected horses. Phylogenetic analysis of the 18S rRNA sequences from the positive DNA samples revealed genotypes A, C, and E. These results confirm the presence of equine theileriosis in northern Vietnam, highlighting the need for nationwide studies of equine piroplasmosis involving larger sample sizes.

The online version contains supplementary material available at 10.1007/s00436-026-08630-4.