Dynamics of equi-factor antibodies in sera of foals kept on farms with differing histories of Rhodococcus equi pneumonia.

The article studies the presence of R. equi antibodies in foals and mares living in two different horse-breeding farms with varying history of R. equi infections. Two different tests, EFN and REO, are used to track antibodies in the study subjects. The findings show that while a higher number of antibodies were found on Farm A, which had a positive history of R. equi infection, the difference was not significant. Onset of EFN positivity was prevalent in foals from both farms at one month of age and peaked in the third and fourth months, but the resistance decreased with time.

Research Methodology

• The research was conducted in two different horse breeding farms – one with a history of R. equi infection (Farm A) and another without such history (Farm B).
• In both farms, the mares and their foals were analyzed for the presence of equi-factor antibodies.
• To conduct the tests, two types of assays were used – the equi-factor neutralization (EFN) and the reverse Elek-Ouchterlony (REO) precipitation tests.
• The researchers have chosen samples from different categories of mares i.e., 25 mares that are positive in both EFN and REO tests, and 25 mares which are negative in both tests from Farm A; from Farm B, 25 mares with negative EFN and positive REO and 25 mares with negative in both tests were studied.

Data Collection

• The researchers collected serum samples of mares one week before birthing, and then collected serum samples from both mares and foals at the end of every month up to six months after the birth of the foals.
• Further samples were collected at eight and twelve months mark.

Observations and Inferences

• A higher number of seropositive subjects were observed on Farm A. However, the difference between both farms was not found to be significant.
• The smallest number of seropositive subjects was found amongst the foals of negative EFN and positive REO mares.
• The researchers found that more foals came positive in the REO test than in the EFN test.
• They also observed that EFN positivity starts showing up for foals from both farms in the first month of their life, peaks in the third and fourth months with titres values varying between 1:64 and 1:2048, and then falls until it disappears or gets reduced to 1:4.

Conclusion

• The results demonstrate that subclinical R. equi infection is common in horse farms. The research does not establish a significant difference between the seropositivity in farms with differing histories of R. equi pneumonia.