Salmonellosis in hospitalized horses: seasonality and case fatality rates.

This study examines patterns of Salmonella infection (Salmonellosis) in horses over an 11-year period, highlighting a peak seasonality between June and September, identifying the prominent Salmonella serotypes causing illness and death in horses, and noting an overall case fatality rate of nearly 45%.

Research Methodology and Duration

• The research examined cases of Salmonellosis in horses over a span of 11 years (July 1971 through June 1982). These horses were studied while they were hospitalized.
• A time series study was conducted using 10 years’ worth of data, encompassing 207 cases.

Findings: Seasonality and Outbreaks

• The research discovered a peak seasonality for the disease, occurring from June through September.
• Three major outbreaks were observed during this time, although no apparent periodicity, or recurring patterns in the timing of the outbreaks, was identified.

Findings: Salmonella Serotypes

• The study identified 18 Salmonella serotypes that caused clinical salmonellosis in horses.
• However, 84% of the cases and 90% of the deaths were caused by 5 dominant serotypes: Salmonella typhimurium, S typhimurium var copenhagen, S anatum, S kottbus, and S saint-paul.

Case Fatality Rate

• Overall, the case fatality rate (the proportion of sufferers who die from the disease) for horses with Salmonellosis was found to be 44.9%.
• Considering only single infections, horses infected with Salmonella typhimurium and S typhimurium var copenhagen experienced a significantly higher case fatality rate of 60.4%, compared to 32.3% for horses infected with other Salmonella serotypes.

To sum up, the study offers valuable insights into the behavior of Salmonellosis in horses over a significant period of time. It identifies the peak season for the disease, the most harmful strains of Salmonella for horses, and the associated mortality rates, which can be instrumental for future research and animal healthcare policies.