Hendra Virus Returns To Australia

The Australian Animal Health Laboratory has confirmed that the Hendra virus (HeV), otherwise known as equine morbillivirus, has made a third appearance in Australia. According to ProMED (Program for Monitoring Emerging Diseases), "The diagnosis is based on histology, immuno-peroxidase, and PCR (polymerase chain reaction) testing of formalized lung tissue and electron microscopy." Hendra virus is an often-fatal respiratory disease that can affect humans and horses.

The first documented cases of Hendra virus, occurred in 20 Thoroughbred racehorses in the Brisbane suburb of Hendra in 1994. The disease migrated from horse to human when the trainer of those horses and a stable hand also were found to be infected by the virus. Both humans infected could be traced back to having contact with the infected horses in 1994. The Hendra virus proved fatal for the trainer. All horses either died or were euthanized.

The second incident took place in Mackay, a coastal town north of Brisbane. Two horses and a farmer died. The farmer died from severe meningoencephalitis which was the result of the Hendra virus after it lay latent for one year before reactivating to cause the fatal encephalitis.

No connection was found between the Brisbane and Mackay incidents.

The most current case of Hendra virus occurred in January of this year, according to a release by ProMED. The horse involved was an adult Thoroughbred mare used for polocrosse. According to ProMED's web site, "The mare died early on Jan. 18, 1999, after an illness lasting 24 hours. Clinical signs included anorexia, depression, gait abnormality, ataxia, and facial edema. At death, large quantities of froth flowed from the nostrils. This froth was described as yellow in color. The appearance of sclera suggested some jaundice."

The mare was kept in a paddock within the residential area of a beachside community near Cairns. Since her death, her paddock companion has tested negative for HeV by an ELISA test (enzyme-linked immunosorbent assay). According to ProMED, "Both horses occupied the paddock continuously for the past two months with no reported horse movement onto or away from the paddock."

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