Between late 1998 and 1999, the spread of a new disease of pigs, characterized by a pronounced respiratory and neurological syndrome, sometimes accompanied by the sudden death of sows and boars, was recorded in pig farms in peninsular Malaysia. The disease appeared to have a close association with an epidemic of viral encephalitis among workers on pig farms. A previously unrecognised paramyxovirus was later identified from this outbreak; this virus was related to, but distinct from, the Hendra virus discovered in Australia in 1994. The new virus was named 'Nipah' and was confirmed by molecular characterization to be the agent responsible for the disease in both humans and pigs. The name proposed for the new pig disease was 'porcine respiratory and neurological syndrome' (also known as 'porcine respiratory and encephalitis syndrome'), or, in peninsular Malaysia, 'barking pig syndrome'. The authors describe the new disease and provide the epidemiological findings recorded among infected pigs. In addition, the control programmes which were instituted to contain the virus in the national swine herd are outlined.
Matched MeSH terms: Paramyxoviridae Infections/prevention & control
Viruses belonging to the family Paramyxoviridae generally have not been recognized as a significant cause of disease in pigs until recently. Between 1997 and 1999, there were large outbreaks of disease in pigs in Australia and Malaysia due to infection with viruses that have been shown to be new members of the Paramyxoviridae family. This article reviews current knowledge of Menangle and Nipah virus infections in pigs, the only major species of domestic animals to experience serious disease after infection with these viruses.
Matched MeSH terms: Paramyxoviridae Infections/prevention & control
An outbreak of infection with the Nipah virus, a novel paramyxovirus, occurred among pig farmers between September 1998 and June 1999 in Malaysia, involving 265 patients with 105 fatalities. This is a follow-up study 24 months after the outbreak. Twelve survivors (7.5%) of acute encephalitis had recurrent neurological disease (relapsed encephalitis). Of those who initially had acute nonencephalitic or asymptomatic infection, 10 patients (3.4%) had late-onset encephalitis. The mean interval between the first neurological episode and the time of initial infection was 8.4 months. Three patients had a second neurological episode. The onset of the relapsed or late-onset encephalitis was usually acute. Common clinical features were fever, headache, seizures, and focal neurological signs. Four of the 22 relapsed and late-onset encephalitis patients (18%) died. Magnetic resonance imaging typically showed patchy areas of confluent cortical lesions. Serial single-photon emission computed tomography showed the evolution of focal hyperperfusion to hypoperfusion in the corresponding areas. Necropsy of 2 patients showed changes of focal encephalitis with positive immunolocalization for Nipah virus antigens but no evidence of perivenous demyelination. We concluded that a unique relapsing and remitting encephalitis or late-onset encephalitis may result as a complication of persistent Nipah virus infection in the central nervous system.
Matched MeSH terms: Paramyxoviridae Infections/prevention & control