Nipah virus, a member of the family Paramyxoviridae, genus Henipavirus, is an emerging zoonotic virus—a virus transmitted to humans via animals. First recognized in 1999 during an outbreak of encephalitis and respiratory illness among pig farmers in Malaysia and Singapore, the virus resulted in nearly 300 cases and more than 100 deaths. To stop the outbreak, nearly a million pigs were euthanized in Malaysia; since then, no outbreaks have been reported in either Malaysia or Singapore. In 2001, a different strain of Nipah virus was identified as the cause of an outbreak in Bangladesh and Siliguri, India. Since that time, outbreaks have been reported annually in Bangladesh and several times in India.
In the Malaysia and Singapore outbreaks, most people became infected because of direct contact with sick pigs, infected through contact with bats. The outbreaks in Bangladesh and India appear to have been either the result of person-to-person contact or through consumption of food, such as raw date palm sap, contaminated with excretions from infected bats. Nipah virus infects a wide range of animals and causes severe disease and death in people. Infection with the Nipah virus can cause encephalitis—inflammation of the brain—or respiratory diseases. Long-term problems, such as convulsions, have been reported, and latent infections can be reactivated.
People infected with Nipah virus can experience a range of responses, from no symptoms at all to fatal encephalitis. Following infection, symptoms usually arise within 5 to 14 days. Initial infection may cause fever and headaches, followed by dizziness, disorientation and mental confusion, which can progress to coma within 24 to 48 hours. Some people may also experience respiratory problems.
There is no treatment or vaccine available for people or animals. The main approach to managing the infection is treatment of the symptoms.
Protective clothing should be worn when handling sick animals or their tissues, including during slaughtering or culling procedures, to prevent animal-to-human transmission. To reduce the risk of bat-to-human transmission, handling of date palm sap should be reduced. Freshly collected date palm juice should not be consumed, and the fruit should be thoroughly washed and peeled before eating. To reduce the risk of human-to-human transmission, close physical contact with infected people should be avoided. Gloves and protective equipment should be worn when taking care of ill people. Regular hand washing after visiting or caring for sick people is advised.