Nipah Virus: What You Should Know

Medically Reviewed by Brunilda Nazario, MD on September 09, 2021
4 min read

Nipah virus (NiV) is zoonotic, which means it spreads to humans through animals. The first known outbreak happened in Malaysia and Singapore in 1999. Now, outbreaks are common in other parts of Asia, like Bangladesh and India.

Only 10% of people with Nipah spread the virus to others, but experts aren’t sure what might affect whether someone passes it on.

The virus can cause a range of symptoms in people, and cases can range from mild to deadly.

Infected fruit bats, also known as flying foxes, are the animal host for this virus. The bats can spread it to other animals, such as pigs, horses, goats, sheep, cats, and dogs. And those animals -- or the bats themselves -- can give it to people.

Once there’s an initial infection from animal to human, human-to-human transmission is possible.

Nipah virus spreads through:

  • Direct contact with infected animals or the fluids from their bodies (like blood, pee, or saliva)
  • Food contaminated with infected animals’ body fluids
  • Close contact with an infected person or their body fluids (like nasal or respiratory droplets, pee, or blood)

The 1999 Nipah outbreak affected pigs and humans. Nearly 300 people were infected, and more than 100 died.

Some people with Nipah virus are asymptomatic, which means they don’t notice any signs at all.

Other cases can be more serious. Symptoms of Nipah virus usually show up within 4 to 14 days of exposure and include:

  • Fever
  • Headache
  • Cough
  • Sore throat
  • Trouble breathing
  • Vomiting

These may be followed by seizures and encephalitis, or brain swelling, which causes problems like disorientation, drowsiness, and confusion. Within 24 to 48 hours, the person may go into a coma.

The virus is deadly in an estimated 40% to 75% of cases. The severity of an outbreak depends on how well the affected area manages its cases.

In some people, the virus can cause dormant or latent infections. This means symptoms or death could happen months or even years after contact with the virus.

Most people with Nipah who survive encephalitis make a full recovery. Some may have long-term side effects such as convulsions or personality changes.

Because the initial signs of the virus can also be symptoms of other conditions, doctors rarely diagnose Nipah at first.

But if you show more symptoms or if you’ve been in an area where Nipah is common, your doctor may diagnose it through tests like:

  • Real-time polymerase chain reaction (RT-PCR). This test uses throat or nasal swabs, cerebrospinal (brain and spine) fluid, pee, and blood to test for Nipah virus in its early stages.
  • Enzyme-linked immunosorbent assay (ELISA). Doctors use this test to look for antibodies. This will help identify Nipah virus in later stages or after recovery.

There are no drugs or vaccines that directly treat a Nipah virus infection.

Doctors use supportive care instead. This means they focus on rest, hydration, and treating specific symptoms as they happen.

Researchers are looking into Nipah virus treatments that involve the immune system, called monoclonal antibodies. Experts have also studied remdesivir, an antiviral medicine, in infected primates.

Doctors used the antiviral ribavirin to treat a small number of people during the initial Malaysian outbreak. But it’s unclear how well it works.

Because there’s no vaccine against Nipah, the key to lower infection rates in people is through awareness. This includes avoiding contact with infected people and washing your hands regularly, especially after visiting with someone who’s sick.

The best way to prevent any outbreak is to cut it off at the start. Experts recommend routine and thorough cleaning and disinfection of pig farms. If there is an outbreak, areas with animals should go into quarantine right away.

In areas where the virus is common, public health groups also recommend:

  • Keeping bats away from date palm sap and other fresh foods
  • Boiling freshly collected date palm juice
  • Thoroughly washing and peeling all fruits before you eat them
  • Throwing away any fruit with signs of bat bites
  • Using gloves and other protective coverings when around sick animals and their tissue
  • Avoiding contact with infected pigs
  • Considering the presence of fruit bats when establishing a farm
  • Keeping pig feed and pig sheds protected from bats

Sometimes, infected animals may need to be culled -- killed to cut their population -- to lower the risk of transmission to humans. Experts must carefully bury or cremate the animal remains to reduce any chances of further spread.