Encephalitozoon infection in a still-born foal.

This study investigates the case of a Clydesdale foal that was stillborn. An infection of the Encephalitozoon cuniculi parasite was found in the foal’s kidneys during a post-mortem examination.

Investigation Method and Findings

• The research was initiated based on the case of a Clydesdale foal that was observed to be stillborn near full term. The researchers conducted a microscopic examination on the foal.
• Upon initial macroscopic examination, the foal’s placenta appeared normal. However, the foal displayed pulmonary atelectasis and faint white mottling on its kidneys, which indicates a possible infection or inflammation.
• The microscopic examination revealed a severe lymphoplasmacytic interstitial nephritis in the kidneys. This is a type of inflammation caused by an influx of lymphocytes and plasma cells in the kidney’s interstitial tissue.

Presence of Encephalitozoon cuniculi

• In the affected kidneys, numerous organisms bearing resemblance to Encephalitozoon cuniculi were found. Encephalitozoon cuniculi is a type of unicellular parasite that often causes disease in domestic rabbits but can also infect a wide range of hosts, including horses.
• The presence of this parasite was identified in areas of inflammation, renal glomeruli, and intracellular cysts in the renal tubular epithelial cells. Gram-positive staining techniques were used to confirm the presence of these organisms.

Ultrastructural Findings

• Further examination revealed that the organisms demonstrate typical characteristics of Microsporidia. They possessed a polar vacuole and a spiral filament, both of which are distinctive traits of this group of parasitic fungi.
• However, the organisms were not detected in the other organs that were examined, suggesting that the infection with the Encephalitozoon cuniculi was confined to the kidneys of the stillborn foal.

This study provides key insights into an instance of Encephalitozoon cuniculi infection in horses, contributing to our understanding of the disease’s presentation and localization.