# Nationwide Serological Survey of Equine Trypanosomosis in Kazakhstan

## TL;DR

This study surveyed equine trypanosomosis in Kazakhstan using blood tests and found regional differences in antibody levels, suggesting exposure to parasites but not confirming specific infections.

## Contribution

This is the first nationwide serological survey of equine trypanosomosis in Kazakhstan, revealing regional variation and diagnostic limitations.

## Key findings

- Seropositivity to equine trypanosomes was detected in 4.73% of samples, with regional variation from 0% to 16.52%.
- PCR testing did not confirm Trypanosoma equiperdum, but one sample tested positive for Trypanosoma evansi.
- CFT results suggest exposure to trypanosomes but cannot reliably distinguish between T. equiperdum and T. evansi.

## Abstract

Equine trypanosomosis remains an important veterinary concern in regions where horses play a significant economic and cultural role. In Kazakhstan, comprehensive nationwide data on the seroepidemiological status of equine trypanosomes are limited. The aim of this study was to assess the serological distribution of equine trypanosomosis across all administrative regions of Kazakhstan using complement fixation testing (CFT). A total of 6065 equine serum samples were collected from seventeen regions between 2023 and 2025. Antibodies against members of the Trypanozoon subgenus were detected using a WOAH-recommended CFT protocol. Overall seropositivity was 4.73%, with substantial regional variation ranging from 0% to 16.52%. Statistically significant differences in seroprevalence were observed between regions (p < 0.001), and mixed-effects modelling indicated considerable regional clustering. PCR testing of seropositive samples did not confirm the presence of Trypanosoma equiperdum, while one sample tested positive for Trypanosoma evansi. These findings suggest that CFT seropositivity reflects exposure to equine trypanosomes rather than confirmed dourine infection. Given the inability of CFT to reliably distinguish between T. equiperdum and T. evansi, species-level attribution remains uncertain. This study provides the first nationwide overview of serological reactivity to equine trypanosomes in Kazakhstan. The results highlight regional heterogeneity in antibody detection and underscore the need for expanded molecular surveillance and improved species-specific diagnostic tools to clarify the epidemiological status of equine trypanosomosis in the country.