NEW DELHI: Nipah virus (NiV) infection is an emerging zoonosis that causes severe disease in both animals and humans. The natural host of the virus is fruit bats of the Pteropodidae Family, Pteropus genus. Here are a few facts about the virus
The natural host of this virus is believed to be fruit bats of the Pteropus species, four of which have been demonstrated to have serologic evidence of infection with this virus. The virus has also been isolated from fetal tissue and uterine fluids of these bats.
- Nipah and Hendra viruses are two related zoonotic pathogens that have emerged in the Asia-Pacific region. Both are RNA viruses that belong to the Paramyxoviridae family.
- The viruses jump the species barrier and infect a secondary animal host (eg, pigs or horses), and transmit infections to humans. In addition, the Nipah virus may be able to spread from human to human.
- Nipah virus primarily causes an encephalitic syndrome with a high mortality rate. The characteristic MRI abnormalities are multiple, small (less than 5 mm), asymmetric focal lesions in the subcortical and deep white matter without surrounding edema.
- The incubation period ranges from 7 to 40 days. The initial presentation is non-specific, characterized by the sudden onset of fever, headache, myalgia, nausea and vomiting.Meningismus is seen in approximately one-third of patients although marked nuchal rigidity and photophobia are uncommon. Patients infected with Hendra virus have presented with fever and influenza-like illnesses, or with meningoencephalitis.
- The diagnosis of Nipah virus can be established using an Enzyme-Linked Immunoassay (ELISA). Supportive care is the mainstay of treatment and infected patients may requireintensive care monitoring.
The WHO estimates the case fatality rate at 40 per cent to 75 per cent.
- Fruit bats of the Pteropodidae family are the natural host of the Nipah virus.
- Nipah virus can be transmitted to humans from animals (such as bats or pigs), or contaminated foods and can also be transmitted directly from human-to-human.
- According to the WHO, Nipah virus is a newly emerging disease that can be transmitted from its reservoir (natural wildlife host), the flying foxes (fruit bats), to both animals and humans.
- It takes its name from Sungai Nipah, a village in Malaysia where it was first identified.
- Symptoms range from asymptomatic infection, acute respiratory infection (mild, severe), and fatal encephalitis. Infected people initially develop influenza-like symptoms of fever, headache, myalgia, 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 Nipah virus was first recognised in 1999 during an outbreak among pig farmers in Malaysia.
It was also recognised in Bangladesh in 2001, and nearly annual outbreaks have occurred in that country since. The disease has also been identified periodically in India. Last year, the virus killed 17 people in Kerala.
During the first recognised outbreak in Malaysia, which also affected Singapore, most human infections resulted from direct contact with sick pigs or their contaminated tissues, according to WHO.
Transmission is thought to have occurred via unprotected exposure to secretions from the pigs, or unprotected contact with the tissue of a sick animal.