BASICS
- HeV (formerly known as equine morbillivirus) is an acute and frequently fatal viral disease of horses that causes respiratory and/or neurologic signs and is zoonotic
- An outbreak of HeV in 1994 (Hendra, Queensland, Australia) was characterized by rapidly progressive primarily respiratory signs and death/euthanasia in 14 of 21 Thoroughbred horses. Most cases since have displayed primarily neurologic signs. There have now been 72 confirmed equine cases, confined to Queensland and New South Wales, all of which have died/been euthanized
- There have been 7 confirmed human cases of HeV, 4 of these fatal
- Natural asymptomatic seroconversion was confirmed in 1 dog
- Apart from the 1994 Hendra outbreak and an outbreak in 2008, most other incidences have involved single horses, occasionally 2–4 horses. Individual cases have been easily isolated and the virus does not appear to be highly contagious
- HeV is a member of the genus Henipavirus in the Paramyxoviridae family
- Flying foxes (fruit bats or Pteropodidae) are the natural reservoir of HeV
- The incubation period in experimentally infected horses is 5–16 days (possibly up to 31 days)
- The clinical course is very acute, with death occurring within 48–72 h of onset in approximately 75% of cases
- Initial signs are nonspecific—anorexia, depression, fever (up to 41°C), and restlessness, with progression to acute respiratory and/or neurologic signs that are rapidly progressive
- Commonly reported signs in natural cases include tachycardia and tachypnea, nasal discharge, congested/hyperemic mucous membranes, muscle fasciculations, ataxia, circling, blindness, seizures, and recumbency
- Sudden death of 1 or more horses in an affected region should be treated with high suspicion
- HeV is not endemic in the Queensland horse population—flying foxes (fruit bats or Pteropodidae) are the natural reservoir for HeV, with sporadic “spillover” of HeV to horses causing natural cases of infection
- No outbreaks of HeV have been identified outside Australia
- HeV has been isolated from flying fox urine, uterine fluid, and fetal tissue. The source of infection for the horse is likely food or water contaminated with these materials
- Unvaccinated horses kept outside in areas attractive to flying foxes are at higher risk
- Close contact appears necessary for disease transmission between horses or from horses to humans, via infected body fluids or on fomites
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS