Glanders re-emerging in few horses in East-Azerbaijan, Iran

Glanders is a zoonosis caused by Burkholderia mallei (B. mallei). Glanders has been re-emerging in recent years due to war in the Middle East, unauthorized transfer, the lack of formulated action plans, etc. The prevalence of glanders in Iran and the risk of B. mallei transmission and infection is high, therefore requires the quick identify this disease in animals, particularly in horses. This study investigated glanders re-emerging in horses in East Azerbaijan Province, Iran. From 22 September 2020 to 20 March 2021, six-month periodic tests such as the complement fixation test (CFT) were implemented by the Veterinary Administration of East Azerbaijan to detect glanders in horses. In the case of positive CFT results, the mallein test was conducted. According to the test results, blood samples were taken to culture and prepare serum for the ELISA test. Deep swab samples were collected from nasal mucosa, lymph fluid, and blood. The CFT results indicated 12 horses were susceptible to glanders, and three horses were diagnosed with glanders based on the mallein confirmatory test results. B. mallei were not isolated in culturing the samples. Three cases were positive in the ELISA test which was consistent with the CFT and mallein test results. However, the molecular test results were negative. It is challenging to isolate B. mallei in the early stage of disease, and the negative molecular diagnostic test result may be misleading in glanders diagnosis. In susceptible cases with a positive CF test result, glanders can be diagnosed by skin mallein and ELISA tests.