Aujeszky’s disease in horses fulfils Koch’s postulates.

This research article focuses on the discovery of Aujeszky’s disease in horses, its symptoms, pathology, and how this observation confirms Koch’s postulates—a set of criteria used to establish a causative relationship between a microbe and a disease.

Isolation of Aujeszky’s Disease Virus

• The study began with the observation of a horse that displayed severe neurological symptoms, such as excessive sweating, muscle tremors, and periods of mania.
• Upon pathological examination, the researchers found signs of non-suppurative meningoencephalitis, an inflammation of the brain and the membranes that surround it. This is indicative of an infection.
• From the brain of this horse, Aujeszky’s disease virus was isolated and grown in a cell culture for further study.

Confirmation of Koch’s postulates

• Koch’s postulates are a set of guidelines used to identify whether a specific microorganism is the cause of a particular disease. They have four criteria: the microorganism is found in all organisms suffering from the disease but not in healthy organisms; the microorganism can be isolated from a diseased organism and grown in pure culture; the cultured microorganism should cause disease when introduced into a healthy organism; and the microorganism can be reisolated from the inoculated organism and shown to be the same as the original microorganism.
• To satisfy Koch’s postulates for Aujeszky’s disease in horses, the isolated virus was introduced into the conjunctiva and nostrils of two healthy ponies.
• Seven days post-inoculation, the ponies developed fevers and started showing abnormal behavior, and on the ninth day, they showed severe neurological signs, which were consistent with the original horse symptoms.
• The virus was then re-isolated from different parts of the Brains and eyes of the ponies, thus confirming that the same virus was responsible for the disease.
• This cycle fulfils Koch’s postulates, conclusively demonstrating that Aujeszky’s disease virus causes the observed disease symptoms in horses.

Implications and Recommendations

• Despite the observed fact that horses do not appear highly susceptible, the study concludes that Aujeszky’s disease should be included in the differential diagnosis of horses showcasing fatal or transient neurological signs, especially in areas where the virus is endemic.
• This inclusion would lead to the more rapid and accurate diagnosis of the disease, ultimately improving treatment.