Canadian researchers are working to develop a more effective vaccine for Rhodococcus equi that they hope will protect foals as young as three weeks of age from the harmful bacterium.

Rhodococcus equi lives in the soil and it can travel to, and multiply within, the foal’s lungs, causing a deadly pneumonia if it is not caught and treated early. The mortality rate of foals with R. equi is 28%, and the bacterium is the leading cause of disease in foals between one and six months of age.

According to the latest edition of the University of Guelph’s Equine Guelph Update, John F. Prescott, MA, VetMB, PhD, professor in the Department of Pathobiology at the Ontario Veterinary College, has been studying the process of how R. equi invades the foal’s system, hiding and replicating inside the macrophage (white blood cells) cells that would typically fight off illness. “Not only does this process prevent the foal’s immune system from responding appropriately, but additionally the bacterium seems to push the foal’s immune response into developing in a way that is guaranteed to be unsuccessful in clearing infection,” the newsletter reports.

The researchers are designing the vaccine to boost the young foal’s ability to fight R. equi and prevent its replication within the macrophages