Airborne Equine Pathogens Surveillance at Major Equestrian Events

ABSTRACT We propose to develop and validate an airborne pathogen surveillance method that will provide early- on detection of Equid herpesvirus -1 (EHV-1) during equestrian events. Once established other relevant pathogens will be included. EHV-1 is an airborne pathogen that can infect the respiratory tract of horses. This infection can lead to further complications such as neurologic disease affecting the horse''s gait, Equid herpesvirus associated myeloencephalopathy (EHM), or abortions. Typically, there is direct and indirect horizontal spread from horse to horse via highly contagious nasal secretions. Despite copious shedding a horse may not show prominent clinical signs of infection. Multiple days/weeks equestrian events with combined stabling of horses with different backgrounds are vulnerable to the incursion of respiratory tract pathogens onto the event grounds. Nasal swab testing at the point of entry to an event will likely catch many/most of the actively pathogen shedding animals. Highly sensitive and specific amplification assays such as PCR or isothermal amplification, are ideal tests for this purpose. However, an animal may be in an early, yet undetectable phase of shedding, which likely will increase in volume with time. Furthermore, EHV-1 is a member of the large herpesvirus family. One unique characteristic of all herpesviruses is ''chronic- persistent infection'' in a dormant stage of latency after first and typically at ''young age'' infection. Latent virus can reactivate and return to the respiratory tract for replication and spread at any time point. While reactivation from latency is rare, it is associated with travel, stress and excitement. Therefore, it is a constant threat for horses housed together at an equestrian event.