New virus is identified in Malaysia epidemic

BMJ 1999; 318 doi: (Published 08 May 1999) Cite this as: BMJ 1999;318:1232
  1. Adam Easton
  1. Manila, Philippines

    Most of the cases, including 98 deaths, in the recent viral encephalitis outbreak in Malaysia have been due to contact with a newly identified virus, spread from pigs to humans, which government officials have named “nipah.” Thousands of pigs have been slaughtered in an attempt to combat the disease.

    Initially, the Malaysian government believed the outbreak, which occurred in the pig farming states of Perak, Negri Sembilan, and Selangor and which has affected 256 people since October 1998, was due to Japanese encephalitis. But epidemiological inconsistencies soon began to be noticed—for instance, most people affected were adult males, rather than very young or old, the groups that tend to be most at risk from Japanese encephalitis.

    Virological studies have now identified a hendra-like virus of the paramyxo family. It has been called a hendra-like virus because of its similarities to a virus first isolated in the Hendra suburb of Brisbane, Australia, in 1994, when 13 racehorses and their trainer died. The natural host for the virus was found to be fruit bats.

    In the Malaysian epidemic the virus seems to be transmitted from pigs to humans through direct contact with body fluids of pigs. There is, as yet, no evidence that transmission can take place from person to person or from eating cooked pork. The incubation period ranges from four to 18 days; severe headache is the first symptom. Severe cases can result in coma and death.

    The Malaysian government has given the virus the name “nipah,” after the plant used in the construction of traditional Malay dwellings.

    The WHO reports that, of the deaths for which tests have been completed, 40 were due to the “nipah” virus, eight to Japanese encephalitis, and 17 to dual infection. People most at risk have been workers at piggeries and abattoirs. A major pig culling operation has proved effective in eliminating the source of human infections.

    Forty one people are still in hospital.

    Embedded Image

    The Malaysian government has ordered 64 000 pigs to be killed

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