# First molecular detection of Francisella tularensis and investigation of Coxiella burnetii in horse sera in Iran

## TL;DR

This study is the first to detect Francisella tularensis in horse sera in Iran, finding a low but significant prevalence with age and sex differences.

## Contribution

The first molecular detection of Francisella tularensis in horses in Iran, highlighting their potential as a weak reservoir.

## Key findings

- 3.4% of horse sera samples were positive for Francisella tularensis genome.
- Younger horses (<5 years) had the highest F. tularensis prevalence (3.93%).
- Stallions showed higher F. tularensis infection rates (5.84%) compared to mares (1.88%).

## Abstract

Infections caused by Francisella tularensis and Coxiella burnetii, as zoonotic diseases, pose a serious threat to the health of humans and animals. To date, there is limited information regarding these diseases in horses. This study aimed to evaluate the prevalence of F. tularensis and C. burnetii in the serum of racehorses in Iran (Golestan province). 350 blood samples were collected from racehorses in four regions of Golestan province, and demographic data (sex, age, and sampling location) were recorded. The collected serum samples were examined by PCR to identify the genomes of F. tularensis and C. burnetii. The results showed that 3.4 % (P < 0.05, 95 % CI: 1.97 % – 5.9 %) of the serum samples were positive for F. tularensis genome, while no positive cases for C. burnetii genome were detected. Additionally, a significant relationship was observed between horse age and F. tularensis infection, with the highest prevalence (3.93 %) detected in animals younger than five years (P < 0.05, 95 % CI: 2.21 % – 6.9 %). Moreover, the study revealed a significant difference in F. tularensis prevalence between sexes, with infection rates of 5.84 % in stallions and 1.88 % in mares. Statistical analysis showed no significant difference between the regions studied and the prevalence of F. tularensis. According to our knowledge, this is the first report of tularemia prevalence in horses in Iran. This study indicates that horses can be considered a potential weak reservoir for F. tularensis.