Leptospira spp. in horses in southern Brazil: Seroprevalence, infection risk factors, and influence on reproduction.

The research article undertakes a study to determine the prevalence of Leptospira bacteria in horses in Southern Brazil, understanding the risk factors of infection, and investigating its effect on horse reproduction. The study reveals a high prevalence of the bacteria, with age and gender serving as considerable infection risk factors with no evident link between Leptospira and reproductive disorders.

Methodology and Sample

• The study examined the presence of Leptospira spp. in 595 samples collected from 60 horse herds in the southern states of Brazil.
• A microscopic agglutination test was performed for 12 serovars that corresponded to 9 serogroups (Sejroe, Icterohaemorrhagiae, Australis, Pyrogenes, Pomona, Canicola, Grippotyphosa, Tarassovi, and Ballum).
• Seroprevalence, as well as risk factors for infection, were the main focus of the study, given the role these might play in reproductive disorders.

Findings

• From the sample, 45.9% of the horses were found to be seropositive, meaning they had been exposed to the bacteria at some point.
• The most frequent serogroups found in the seropositive horses were Icterohaemorrhagiae (covering Icterohaemorrhagiae and Copenhageni serovars) and Ballum (Ballum serovar).
• Among the seropositive animals, 45.4% presented with simple infections and 54.6% had mixed infections.
• The study highlighted a correlation between seropositivity and factors such as age and sex. In their findings, animals above 6 years and females were more likely to be seropositive.

Conclusion

• In conclusion, the research finds a high seroprevalence of Leptospira spp. in southern Brazil, predominantly in the Icterohaemorrhagiae serogroup, and particularly in older animals.
• Contrary to what might have been expected, the location, breed of the horse, and contact with dogs or other domestic animals were not identified as risk factors. Instead, gender emerged as a risk factor.
• On the issue of reproductive disorders, the study did not find any correlation between Leptospira infection and reproductive disorders in horses in the sampled region.