High Seroprevalence of Lawsonia intracellularis in Thoroughbred Farms in Southern Brazil.

The research paper investigates the prevalence of a bacterium named Lawsonia intracellularis in Thoroughbred horses from six farms located in Southern Brazil, reporting that over half of the studied horses exhibited antibodies against the bacterium.

Objective and Methodology

• The study aimed to identify the seroprevalence, or the level of a pathogen in a population as measured in blood serum, of Lawsonia intracellularis in Thoroughbred horses living on six farms in Southern Brazil.
• Researchers collected blood samples from a total of 686 horses during the period of 2019 and 2020. The horses were grouped by age for the purpose of the study.
• The blood samples were collected through a method called venipuncture, directly from the horse’s external jugular vein.
• The researchers used a method called Immunoperoxidase Monolayer Assay to detect the presence of antibodies (IgG). Antibodies serve as an indicator of exposure to an infection, as they are produced by the immune system in response to said infection.

Findings

• The study found that 51% of the evaluated horses had specific antibodies (IgG) against Lawsonia intracellularis, revealing a high prevalence of the bacterium in the horse population. This suggests that the horses had a strong and continuous exposure to the bacterium.
• The highest detection rate of these antibodies was 86.8% in broodmares (female breeding horses older than 5 years), while the lowest detection rate was 5.2%, found in the youngest group of foals aged between 0-6 months.
• With respect to location, Farm 1 presented the highest prevalence of seropositivity against L. Intracellularis at 67.4%. Conversely, Farm 4 had the lowest seroprevalence, recorded at 30.6%.
• Despite the high seroprevalence, there were no evident clinical signs of Equine Proliferative Enteropathy, which is a disease caused by Lawsonia intracellularis, in the sampled horses. This may potentially suggest that horses can be exposed and develop an immune response to the bacterium without showing noticeable symptoms.