Histopathological and diagnostic aspects of glanders based on a case series from Brazil.
Authors: Nassar A F C, Chiebao D P, Fava C Del, Miyashiro S, Castro V, Ogata R A, Yamamora J M, Monteiro C A S, Monteiro E J B
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Glanders Diagnosis in Brazilian Equine Populations Glanders remains a significant zoonotic threat to equine operations, particularly in endemic regions, yet subclinical infections can evade detection through clinical assessment alone. This Brazilian case series of 17 naturally infected horses (including one fetus) across three separate outbreaks examined how histopathology, bacterial culture, and PCR performed in combination, revealing that 37.5% of affected animals displayed no clinical signs despite harbouring *Burkholderia mallei*. Whilst PCR detected the pathogen in 100% of cases (41.3% of individual samples), bacterial culture proved considerably less sensitive at only 8.2% of samples, highlighting the diagnostic superiority of molecular methods for confirming active infection. The predominance of nasal and respiratory presentations over cutaneous disease reflected the typical epidemiology in these outbreaks, yet the identification of seropositive carrier animals without clinical manifestation carries critical implications for disease control: serological programmes alone will fail to identify all infected horses, and combining multiple diagnostic modalities—particularly PCR alongside histopathology—is essential for accurate case confirmation and preventing transmission through apparently healthy carriers.
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Practical Takeaways
- •Seropositive horses without clinical signs should be considered potential carrier animals and managed accordingly to prevent disease spread in control programmes
- •PCR is a more sensitive diagnostic tool than bacterial culture for B. mallei detection (41.3% vs 8.2% positive samples), making it preferable for case confirmation
- •Clinical signs alone are insufficient for glanders diagnosis—serological screening combined with molecular testing is necessary to identify all infected animals, including asymptomatic carriers
Key Findings
- •All 17 tested animals were PCR-positive (100%) for B. mallei on at least one sample, while only 8.2% (10/121) of samples yielded positive bacterial culture
- •37.5% (6/16) of naturally infected horses showed no clinical signs despite serological positivity
- •Nasal and respiratory forms were the predominant clinical presentations across three outbreaks, with cutaneous form occurring less frequently
- •Combined diagnostic approach using histopathology, bacterial culture, and PCR was essential for confirming cases and characterizing disease presentation