Cause of fatal outbreak in horses and humans traced.

This research study details how a team of investigators identified a previously unrecognized virus causing a deadly outbreak in horses and a human in Australia in 1994. The cause was traced to a new morbillivirus, aptly named equine morbillivirus (EM).

Background

• In September 1994, a fatal outbreak occurred in Brisbane, Australia, which resulted in the deaths of eleven horses and severe illness in their trainer. This outbreak pointed towards an unidentified, potentially exotic infection raising immediate concerns about a possible epidemic.

Investigation Process

• Upon identifying the devastating impact of the unknown virus, Australian health authorities launched a significant effort to trace the origin of the disease. This involved multiple experts, including Keith Murray, chief of the Commonwealth Scientific and Industrial Research Organization’s high-security Australian Animal Health Laboratory, and Linda Selvey, a medical epidemiologist at Queensland’s health department.
• The team received the tissue samples of the deceased horses and began a rigorous process to identify the cause of the illness. Two possibilities were initially considered – poisoning or a new, highly virulent virus.

Findings

• The team’s investigation led to the discovery of a previously unknown morbillivirus, a group of viruses that include the likes of canine distemper virus, seal plague virus, rinderpest virus, and measles virus. The newly discovered virus was named as equine morbillivirus (EM).
• Despite the discovery, many mysteries about the virus remained unsolved, such as its origin or potential spread. It was noted that until the natural host of EM is determined, the possibilities of further outbreaks could not be ruled out.

Impact

• The discovery of the equine morbillivirus marked a significant progress in veterinary epidemiology. The rapid detection and identification of the virus helped prevent a potential epidemic.
• This study also emphasized the need for continuous surveillance and research for unknown pathogens to better predict, prevent, and respond to possible future outbreaks.