The prevalence of Francisella tularensis in horse herds in Turkey

Tularemia caused by Francisella tularensis can exist in nature over a long period of time. The disease can be transmitted by ticks, biting flies, water exposure, food, and aerosols. F. tularensis infections occur especially in the North America, Europe, and Asia. Tularemia is often water-associated and effects humans and an array of animals including domestic animals, wild small mammals, and fish. In horses, there is almost no information about tularemia. However, fever, dyspnea, incoordination and depression have been described. This study aimed to estimate prevalence of F. tularensis among horse herds in Turkey. Totally 109 horses aged 36 months and older were randomly sampled from different regions of Turkey. Blood serum samples were investigated by Microagglutination Test (MAT) in terms of F. tularensis antibody. Prevalence changes were estimated via the diagnostic values (51% for sensitivity and 99% for specificity) reported for the MAT. The animal, within-herd and between-herd apparent prevalences were calculated 40.4% (95% CI = 31.6 to 49.8%), 41.1% (95 CI = 32.3 to 50.6%) and 81.8% (95% CI = 52.3 to 94.9%), respectively. True prevalences were calculated by conversion of the apparent prevalences via the Rogan-Gladen estimator. True animal, within-herd, and between-herd prevalences were calculated as 78.7% (95% CI = 61.3 to 97.5%), 80.2% (95 CI = 62.5 to 99.2%) and 161.6% (95 CI = 103 to 187.7%), respectively. The results provide useful information regarding the prevalence of tularemia in horse herds in Turkey and will hopefully attract the special attention of veterinarians and promote the establishment of an efficient control programme.