Adaptation and validation of a bacteria-specific enzyme-linked immunosorbent assay for determination of farm-specific Lawsonia intracellularis seroprevalence in central Kentucky Thoroughbreds.

This study validates a modified enzyme-linked immunosorbent assay (ELISA) test for detecting exposure to a bacteria that causes equine disease on thoroughbred farms. It revealed a significant prevalence of the bacteria Lawsonia intracellularis, particularly on farms with a recent history of the associated disease, equine proliferative enteropathy (EPE).

Research Methodology

• The researchers used an ELISA test, which was adapted to detect the presence of Lawsonia intracellularis-specific antibodies in horses.
• A total of 337 Thoroughbreds from 25 farms in central Kentucky were enrolled in the study and their blood samples were collected monthly from August 2010 to January/February 2011.
• Farms were categorized into three groups based on their history with EPE in the previous three years.

Main Findings

• The ELISA test demonstrated a within-test variation of 6.73% and a between-test variation of 9.60%, indicating reasonable consistency.
• Overall, 68% of the tested horses had antibodies specific to Lawsonia intracellularis, varying from 14-100% on individual farms.
• Farms with a recent history of EPE showed significantly higher seroprevalence, meaning a higher proportion of horses exhibited exposure to the bacteria.
• Likewise, farms with no recent EPE history showed fewer ELISA units (EU), suggesting less exposure to the bacteria.
• Exposure to the bacteria appeared to have a bimodal distribution, with peaks in fall and winter.

Conclusions and Implications

• The researchers concluded that the adapted ELISA test is useful for determining exposure levels to Lawsonia intracellularis.
• The high seroprevalence rates and bimodal exposure patterns suggest that farms with a history of EPE may continue to be at risk, even beyond the early winter period.

The findings infers a significant level of seroprevalence to Lawsonia intracellularis among Thoroughbreds on central Kentucky farms. Higher rates of exposure were observed on farms with a recent history of EPE. This study gives a better understanding of the prevalence and exposure patterns of Lawsonia intracellularis and could be fundamental in the management and prevention of EPE in Thoroughbreds.