Nipah virus is an RNA virus that was first identified after an outbreak involving severe respiratory illness in pigs and encephalitic disease in humans in Malaysia and Singapore in 1998 and 1999.
Although Nipah virus has caused only a few outbreaks, it infects a wide range of animals and causes severe disease and death in people, making it a public health concern.
- Nipah virus is a zoonotic virus (a virus transmitted to humans from animals). During the initial outbreaks in Malaysia and Singapore, most human infections resulted from direct contact with sick pigs or their contaminated tissues.
- Nipah virus can be transmitted to humans from animals (bats, pigs), and can also be transmitted directly from human-to-human. Fruit bats of the Pteropodidae family are the natural host of Nipah virus.
- Transmission is thought to have occurred via respiratory droplets, contact with throat or nasal secretions from the pigs, or contact with the tissue of a sick animal.
- In the Bangladesh and India outbreaks, consumption of fruits or fruit products (e.g. raw date palm juice)contaminated with urine or saliva from infected fruit bats was the most likely source of infection.
Signs and symptoms
- Infected people initially develop influenza-like symptoms of fever, headaches, myalgia (muscle pain), vomiting and sore throat.
- This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis.
- Some people can also experience atypical pneumonia and severe respiratory problems, including acute respiratory distress.
- Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours.
- The incubation period (interval from infection to the onset of symptoms) is believed to range between from 4-14 days. However an incubation period as long as 45 days have been reported.
- Initial signs and symptoms of Nipah virus infection are non-specific and the diagnosis is often not suspected at the time of presentation. This can hinder accurate diagnosis and creates challenges in outbreak detection and institution of effective and timely infection control measures and outbreak response activities.
- Main tests including real-time polymerase chain reaction (RT-PCR) from bodily fluids as well as antibody detection via ELISA.
- Different tests include:
- Enzyme-linked Immunosorbent Assay (ELISA)·
- Polymerase Chain Reaction (PCR) Assay·
- Virus Isolation by cell culture.
There are currently no drugs or vaccines specific for Nipah virus infection although this is a priority disease on the WHO R&D Blueprint. Intensive supportive care is recommended to treat severe respiratory and neurologic complications.
- Controlling Nipah virus in domestic animals
- Currently, there are no vaccines available against Nipah virus. Routine and thorough cleaning and disinfection of pig farms (with appropriate detergents) may be effective in preventing infection.
- If an outbreak is suspected, the animal premises should be quarantined immediately. Culling of infected animals – with close supervision of burial or incineration of carcasses – may be necessary to reduce the risk of transmission to people. Restricting or banning the movement of animals from infected farms to other areas can reduce the spread of the disease.
- Reducing the risk of infection in people
- In the absence of a licensed vaccine, the only way to reduce infection in people is by raising awareness of the risk factors and educating people about the measures they can take to reduce exposure to and decrease infection from Nipah virus.