Ocular onchocerciasis in the horse.

This research paper investigates ocular onchocerciasis, a disease affecting horses’ eyes caused by a parasite, and attempts to understand the role of the parasite in the development of eye disorders in horses.

Background

• The research commences with an introduction to Onchocerca, a parasite that causes a variety of pathological changes in the host’s eyes, hence termed ocular onchocerciasis. This condition has been observed in humans since 1931, notably impacting a significant populace in Africa.
• The manuscript references Rodger’s study in 1960 that disclosed that 38 million people were suffering from onchocerciasis, with half a million having lost their sight due to it. The author expresses that Rodger’s comprehensive study of the disease progression and pathology provides valuable insight into the various ways this parasite affects the eyes.

Ocular onchocerciasis in Horses

• The existence of ocular onchocerciasis in horses was initially proposed by Iyer in 1939 by observing a horse with uveitis, an inflammation of the eye’s middle layer.
• Subsequently, Bohm and Supperer proposed that changes in horse’s eyes could be linked to the parasite Onchocerca cervicalis. Supporting evidence for this theory was supplied by both Lagraulet and Roberts.
• The author conducted studies in Austria and California, pinpointing equine ocular onchocerciasis as an acute or chronic kerato-uveitis. Symptoms recurrent iridocyclitis were observed. The author also commented upon certain skin lesions and ocular indicators of onchocercal infection.
• Dimic, however, challenged this represented relationship between the microfilariae and equine periodic ophthalmia, arguing the symptoms were rather coincidental. He argued that these parasites are so common that they are considered normal inhabitants and not associated with any ocular diseases.

Objective of the Paper

• The author aspires to clarify the role of this parasite in causing eye diseases in horses through extensive research that began in 1960 in Vienna, Austria and continued at the School of Veterinary Medicine at the University of California.