Echinococcus granulosus (Taeniidae) and autochthonous echinococcosis in a North American horse.

This research discusses the first identified case of a horse specifically from North America, being infected with a parasite called Echinococcus granulosus leading to a condition known as echinococcosis. The study suggests that due to the horse’s contact with foxes and certain hunting practices, this strain of parasite could potentially become established in the eastern United States and thus be a risk to the equine population.

Identification of the Infection

• The researchers found Echinococcus granulosus, a parasitic worm, in a 14-year-old thoroughbred horse during a post-mortem examination. This horse was originated from Virginia and raised in Maryland. Interestingly, this is the first reported case of a North American horse being affected by this parasite.
• Three mature, viable hydatid cysts of Echinococcus granulosus were found in the horse’s liver.

Characteristics of the Parasite and its Infection

• The protoscolices (the tiny, immature form of the parasite) examined had two rows of rostellar hooks, adaption the parasite uses for attachment to the host. The dimensions of these hooks were found to be consistent with those typically seen in the E. granulosus strain that infects horses, which is primarily reported from the United Kingdom.
• The disease caused by E. granulosus – echinococcosis, is of concern as it creates cysts in various organs of the host, which can cause severe health implications.

Contributing Factors and Suggestions for Future Action

• The researchers suggest that the horse’s history of fox hunting increases its chances of acquiring infection. The infection can be maintained in horse populations due to the local practice of feeding raw horse viscera (intestines) to dogs – this can create a cycle of transmission between species.
• Given this evidence, the researchers recommend monitoring and further investigation into the possible establishment of the E. granulosus parasite strain in the eastern U.S.A. and its potential impacts on the horse population.