Faecal shedding and serological cross-sectional study of Lawsonia intracellularis in horses in the state of Minas Gerais, Brazil.
Authors: Guimarães-Ladeira C V, Palhares M S, Oliveira J S V, Ramirez M A, Guedes R M C
Journal: Equine veterinary journal
Summary
# Editorial Summary: *Lawsonia intracellularis* in Brazilian Horses Proliferative enteropathy, caused by the intracellular bacterium *Lawsonia intracellularis*, has been well-documented in horses across North America, Australia and Europe, yet remained unreported in Latin America until this investigation. Guimarães-Ladeira and colleagues conducted a cross-sectional serological and faecal screening of 223 horses across 14 commercial farms and a university teaching herd in Minas Gerais, Brazil, employing immunoperoxidase serology to detect anti-*Lawsonia* IgG antibodies and PCR to identify bacterial shedding in faeces. Of the cohort, 21 horses (9.4%) tested seropositive with IgG titres of 1:60 or higher, whilst 7 animals (3.1%) shed bacterial DNA in faeces—notably, all shedding horses displayed no clinical signs, confirming subclinical infection circulating in the population. This finding is clinically significant because practitioners in regions where proliferative enteropathy remains undiagnosed should now consider *L. intracellularis* in their differential diagnoses for enteric disease, and the presence of asymptomatic shedders raises questions about herd transmission dynamics and whether testing protocols should be expanded in at-risk populations. The study essentially maps a previously unrecognised pathogen within a major equine population, alerting the global equine health community that geographic boundaries for this disease may be considerably wider than previously assumed.
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Practical Takeaways
- •Clinicians in regions where equine proliferative enteropathy has not been reported should consider L. intracellularis as a differential diagnosis for cases of enteric disease
- •Healthy-appearing horses can shed L. intracellularis in faeces, meaning subclinical infection may go undetected without targeted screening
- •Serological testing and faecal PCR are useful diagnostic tools to identify L. intracellularis in horse populations where disease prevalence is unknown
Key Findings
- •9.4% (21/223) of horses were seropositive for L. intracellularis IgG antibodies at titre ≥1:60
- •3.1% (7/223) of horses were faecal shedders of L. intracellularis DNA detected by PCR
- •All faecal shedding horses appeared clinically healthy, indicating subclinical infection occurs in the population
- •This is the first report of L. intracellularis presence in Latin American equine populations