The seroprevalence of Lawsonia intracellularis in horses in The Netherlands.

The research is aimed at investigating the prevalence of antibodies against the bacteria Lawsonia intracellularis, which causes a disease affecting the growth and development of young foals, in horses in The Netherlands. The study finds that this bacteria is widespread and that the presence of antibodies doesn’t always correlate to clinical issues.

Objective and Methodology

• The researchers set out to determine the prevalence of Lawsonia intracellularis, a bacterium responsible for Equine proliferative enteropathy, a disease that affects weanling foals and their development, in The Netherlands.
• Blood samples were collected from healthy foals both pre and post-weaning, along with healthy yearlings and mature horses from multiple farms within The Netherlands.
• The samples were thoroughly analyzed using a blocking ELISA test to detect the presence of specific antibodies against Lawsonia intracellularis.
• Additionally, the study collected data on white blood cell count, packed cell volume, and total protein levels, while investigating the housing conditions of each horse, access to pastures and any possible contact with pig manure on the farms.

Findings

• The prevalence of Lawsonia intracellularis antibodies increased from 15% in foals before weaning to 23% after weaning, while it was 89% in yearlings and 99% in horses older than 2 years.
• There was no significant difference in seroprevalence between horses kept in pastures or stables; both had very high rates at 97% and 100%, respectively.
• The study did not find any significant impact of contact with pig manure on the prevalence of the bacterium.
• Interestingly, the presence of antibodies was not associated with any clinical illness in any of the horses in the study, suggesting having antibodies isn’t directly correlated to disease manifestation.

Conclusions

• The results strongly suggest Lawsonia intracellularis is highly prevalent in The Netherlands. However, seropositivity – the presence of antibodies in the blood – does not inevitably lead to clinical problems.
• The high prevalence of antibodies in adult horses could indicate a long-term persistence of these antibodies or constant exposure to Lawsonia intracellularis.