According to a March University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) bulletin, the lab is seeing a statistically significant increase in positive Lawsonia intracellularis test results as compared to recent years.

Equine proliferative enteropathy (EPE) is an emerging disease of horses that has been reported worldwide. EPE is caused by L. intracellularis, a gram-negative bacterium that invades intestinal crypt cells, primarily in the small intestine, and causes thickening of the intestinal lining. This thickening leads to the clinical signs associated with EPE, including anorexia, weight loss, fever, lethargy, depression, and peripheral/ventral edema (fluid swelling), with colic and diarrhea seen occasionally. A thickened small intestinal wall observed by a veterinarian via abdominal ultrasound, although not reliably observed, is highly suggestive of EPE. Clinical EPE is typically found in weanlings and young yearlings, with only a few reports of older horses being affected.

Lawsonia intracellularis infections have been reported in a number of species, including pigs and laboratory animals, but not humans. EPE is significant not just because of the clinical aspects of the disease, but also because of its economic importance