But horses don’t have to ship internationally to spread the EI virus. Transmission paths include:
- Introducing a new infected horse into your herd that might or might not exhibit clinical signs.
- Direct contact with people, tack, equipment, and surfaces that have been exposed to/contaminated by virus aerosolized by an infected, coughing horse.
- Contact with wild equine populations. A May 2015 outbreak in Arizona was discovered when dead wild burros tested positive for EI.
Fortunately, the mortality (death) rate associated with EI is very low, says Pusterla, adding that serious complications include the secondary bacterial infections mentioned and resulting bronchial pneumonia, which can be serious.
Veterinarians detect these secondary infections using blood counts and possibly X rays and ultrasounds and treat them with antibiotics as needed, adds Fielding. Although not common, viral pneumonia can be deadly in foals that lack maternal antibodies.