Equine leptospirosis in tropical Northern Queensland.

The research paper investigates the spread and impact of leptospirosis in horses in Northern Queensland (NQ), Australia, focusing particularly on the Townsville-Burdekin and Atherton Tableland regions. The study found a high prevalence of the disease across a range of leptospiral serovars, with serovar Arborea observed most frequently, and identified geldings, higher rainfall and proximity to pigs and sugarcane fields as key risk factors.

Methodology

• The researchers conducted a cross-sectional survey across the NQ region. They used serum samples from 429 horses from 172 horse-owning properties to analyze the spread and impact of leptospirosis.
• These samples were taken at veterinary clinics and regional horse shows and were subsequently analyzed using a microscopic agglutination test.
• In addition, the process included interviews with horse owners to assess potential risk factors related to leptospirosis.

Results

• The study found that of the 172 properties that provided samples, horses from 60 properties—equivalent to 35%—showed evidence of exposure to at least one of the Leptospira serovars.
• The prevalence of seropositive properties was at 25% in the Atherton Tableland region and 36% in the Townsville-Burdekin region.
• In terms of serovar divergence, 81 horses had been exposed to a single serovar, while the remainder had been exposed to two or more serovars.
• Out of 20 serovars identified, serovar Arborea was the most dominant and was detected in horses from 29 properties.

Associated Risk Factors

• Geldings—castrated male horses—were more at risk and had an odd ratio of 3.3 of being seropositive for serovar Arborea.
• The study found a strong relationship between the detection of serovar Arborea-positive horses and the average annual rainfall on each property.
• Additionally, the presence of pigs and sugarcane fields in the vicinity was associated with a higher prevalence of serovar Arborea.

Conclusion

• The study concludes that the serological evidence points towards a high prevalence of leptospirosis across horses in NQ.
• The research also indicates that these horses have been exposed to a wide range of Leptospira serovars, with the serovar Arborea being the serodominant.
• The study provides valuable insights and data that can contribute to the development of targeted future efforts in managing and controlling the spread of this bacterial disease.