Seroprevalence and associated epidemiological drivers of glanders in horses: a systematic review and meta-analysis (2002-2026).

Overview

• This research article systematically reviews and analyzes the prevalence of glanders, a contagious disease in horses, by examining studies conducted between 2002 and 2026.
• It also identifies epidemiological factors influencing the disease’s spread and highlights the need for improved surveillance and control strategies.

Background and Objective

• Glanders, caused by the bacterium Burkholderia mallei, is a zoonotic disease primarily affecting equids (horses, mules, donkeys).
• The disease is highly contagious and remains a transboundary issue despite extensive control efforts worldwide.
• There has been no comprehensive synthesis of the epidemiological patterns or factors driving glanders in horses.
• The research aims to estimate the overall seroprevalence (proportion of horses with antibodies indicating infection) and identify key epidemiological drivers based on published studies up to April 2026.

Methodology

• The study follows PRISMA 2020 guidelines for systematic reviews to ensure rigor and transparency.
• Databases searched include PubMed, Scopus, Web of Science, ScienceDirect, Cochrane Library, ProQuest, and Google Scholar.
• Inclusion criteria required studies to report on glanders seroprevalence in horses.
• Quality assessment of studies was done using the Joanna Briggs Institute checklist for prevalence studies, which evaluates risk of bias and study robustness.
• Statistical analyses involved:
  • Random-effects meta-analyses to pool seroprevalence estimates accounting for study variation.
  • Subgroup analyses to evaluate prevalence differences across regions, seasons, and animal condition.
  • Meta-regression to explore temporal trends and other influencing factors.
  • Publication bias assessments to determine if the results might be skewed by selective reporting.
• These analyses were performed using RStudio software version 4.4.3.

Key Findings

• Twenty studies satisfied inclusion criteria for the review and meta-analysis.
• The pooled global seroprevalence of glanders in horses was estimated at approximately 3.02%, with a confidence interval ranging from 0.82% to 6.36%, indicating variability and uncertainty.
• Geographical distribution showed glanders was mainly reported in South Asia and South America.
• The highest prevalence rates were observed in specific locations such as French Guiana and Iraq.
• ELISA (Enzyme-Linked Immunosorbent Assay) was the most commonly used diagnostic method across studies, reflecting its importance in detecting glanders antibodies.
• Environmental and animal-specific factors influenced prevalence:
  • Higher seroprevalence was noted during the rainy season, possibly due to environmental conditions favoring the bacteria’s survival or transmission.
  • Animals with poor body condition showed higher infection rates, suggesting that weaker or immunocompromised horses might be more susceptible.
• Meta-regression showed an increasing temporal trend in glanders seroprevalence, indicating that the disease may be re-emerging or spreading over time despite control efforts.

Implications and Recommendations

• These findings highlight the ongoing public and animal health threat posed by glanders, particularly in endemic regions.
• The study suggests that current surveillance and control measures need strengthening to effectively monitor and reduce the disease burden.
• Standardizing diagnostic approaches, such as wider use of ELISA with validated protocols, could improve detection accuracy and comparability across regions.
• Targeted control strategies taking into account seasonal and animal health factors could aid in reducing transmission.
• The study underscores the importance of coordinated international efforts to prevent further resurgence and to protect equids as well as humans at risk from this zoonotic pathogen.