Definition of Encephalitis, Nipah virus

Encephalitis, Nipah virus: Brain inflammation (encephalitis) due to the Nipah virus that infects pigs and people. Nipah is the name of the first village the virus struck near Kuala Lumpur in Malaysia. (The Nipah virus is similar to Hendra virus that was discovered in Australia in 1994.) Nipah virus caused a severe outbreak of viral encephalitis in Malaysia in 1998-1999.

The main risk factor for Nipah virus encephalitis is recent contact with pigs. Most patients have had direct contact with pigs in the two weeks preceding the onset of the illness. The infection may spread to people through contact with pig secretions such as feces or saliva or through contact with infected dogs.

The spread of the Nipah virus illustrates a problem due to trends in livestock production -- large-scale production and international commerce. Huge hog farms can have tens of thousands of animals. Some infectious agents such as the Nipah virus are associated with intensity of production and concentration of animals in limited spaces. International commerce in meat and poultry now increases the chance of the worldwide dissemination of exotic infectious agents like the Nipah virus.

Bats are believed to be the natural host of Nipah virus. The virus is similar but not identical to Hendra virus, another agent of zoonotic viral disease in which bats are the usual host.