Nipah henipavirus also known as Nipah virus (NiV) is a zoonotic RNA virus present in the genus Henipavirus. NiV was first isolated and identified in 1999 amongst pig farmers and people in close contact with pigs in Malaysia and Singapore. The outbreak lead to the euthanisation of more than one million pigs, having a huge impact on trade in Malaysia. NiV was also identified in Bangladesh in 2001 and the country has suffered outbreaks almost annually since then. Transmission of NiV to humans occurs after direct contact with infected bats (the natural host), pigs or other humans. The 1999 Malaysian outbreak is thought to have occurred as a result of unprotected exposure to secretions or contact with the tissue of infected pigs. The source of infection in Bangladesh in subsequent years has been attributed to contact with contaminated fruit and/or fruit products. In humans, NiV can range from being asymptomatic to acute respiratory infection and fatal encephalitis. After exposure and incubation over a period of 5-14 days, fever and headaches follow, after which comes drowsiness and disorientation. Within 24-48 hours this can progress to a coma. As of May 2018, the case fatality rate was estimated at 40% to 75%. Survivors normally make a full recovery, but approximately 20% of patients can be left with neurological conditions including seizure disorders and personality changes. Control and prevention of NiV can be achieved through thorough cleaning and disinfection of pig farms. In the instances that an outbreak does occur, the premises should be quarantined immediately, and culling of infected animals may be necessary to reduce the risk of human transmission.
