Evaluation of temporal and spatial clustering of horses with Corynebacterium pseudotuberculosis infection.

The research studied patterns of temporal or spatial clustering in horses with Corynebacterium pseudotuberculosis infections that were taken to a veterinary hospital between July 1, 1992, and June 30, 1994, finding out that the infection can be directly or indirectly transmitted.

Methodology

• The study included 134 horses with Corynebacterium pseudotuberculosis infection (case horses) and a control group of 800 horses randomly selected from all horses admitted during the same study period that did not exhibit the infection (non-case horses).
• Admission dates and geographic locations were recorded and analyzed.
• Various statistical tests including Scan, Cuzick & Edwards’, and Knox tests were implemented to verify if there were any patterns of temporal or spatial clustering among the case horses.

Results

• The results from the Scan test were significant for all assessment windows equal to or above 3 days for the 134 case horses, and equal to or above 7 days for a subset of 69 case horses.
• The Cuzick & Edwards’ test results were significant for all data sets.
• A substantial spatial cluster of horses with the infection was seen during the months of October, November, and December 1992.
• Results from the Knox test were significant for temporal intervals between 7 and 56 days and spatial intervals between 4.3 and 6.5 km.
• The Knox(x) test showed higher proportions for temporal intervals of 0 to 7, 8 to 14, 22 to 28, and 29 to 35 days.

Conclusion

• The study found significant spatial and temporal clustering of horses with C pseudotuberculosis infection.
• Analysis strongly suggests that the disease can either be directly transmitted from an infected horse to a healthy one or indirectly via vectors such as insects or contaminated soil within a short distance and time.
• Additionally, the findings indicated an incubation period of the infection to be approximately 3 to 4 weeks.