Surveillance of equine glanders in India (2019-2023): Prevalence estimate, risk analysis and future strategy

Equine glanders, a notifiable zoonotic disease caused by Burkholderia mallei, continues to pose a significant health and regulatory challenge in India. This study summarizes the outcomes of a nationwide sero surveillance programme conducted between January 2019 and December 2023 to assess the distribution and temporal trends of glanders in equid populations. A total of 158,798 serum samples collected from 391 districts across 19 states and three union territories were screened using Hcp1-based indirect ELISA, followed by confirmatory testing through the complement fixation test. During the five-year period, 728 seropositive equids were detected from 138 districts. The overall seroprevalence showed a marked decline from 0.627% in 2019 to 0.253% in 2023, indicating improved disease control, likely supported by the implementation of the National Action Plan for Glanders (2019). Uttar Pradesh accounted for approximately 60% of all positive cases, reflecting intense equine movement and trade in the region. Seasonal analysis revealed higher seropositivity during winter (0.569%) compared with spring-summer (0.377%) and monsoon months (0.43%). Among agroclimatic regions, the East Coast Plains and Hills recorded the highest prevalence (1.462%). Several risk factors-including unorganized equine management systems, frequent animal movement for cultural events, and insufficient awareness of glanders regulations among field veterinarians-were identified as contributors to disease persistence. Enhanced surveillance, particularly in southern, eastern, and northeastern India, covering at least 10-15% of the equine population, is recommended for timely detection and control. Given the zoonotic nature of glanders, testing of in-contact human samples should be conducted for glanders testing.