AG index page FAO homepage
Print this page | Close

Nipah virus Frequently asked questions


updated August 2018

 

What is Nipah and where is it found?

 

Nipah is a zoonotic disease, meaning it is transmitted from animals to humans. The disease is caused by a virus closely related to Hendra virus, both of which are members of the family Paramyxoviridae. Nipah was named after the village in Malaysia where pig farmers first became ill with the disease, and other human outbreaks have been reported in Singapore, Bangladesh and India. Fruit bats of the Pteropus genus, also known as flying foxes, are the natural hosts for Nipah virus. There is evidence the virus is circulating in fruit bats in Cambodia, Thailand, Indonesia, the Philippines, Ghana and Madagascar, but there have been no reports of human disease in these countries to date.

 

How is Nipah virus spread?

 

Fruit bats are the main reservoir for Nipah and they can transmit the virus to humans through direct and indirect contact with their urine, feces, or saliva. Contact with fruit bats or their urine, feces or saliva should thus be strictly avoided in Nipah-affected areas. Transmission has also been associated with consumption of drinks made from raw date palm sap (including fermented drinks) contaminated with infectious bat saliva, urine or feces.

 

Fruit bats are the natural hosts of the disease, and pigs can become infected through contact with the urine, feces, or saliva of bats that have contaminated pig farms or feed. Humans can then subsequently become infected through direct contact with the saliva, respiratory secretions, urine and tissues from infected pigs. While pigs have an important role in amplifying the disease, which can then cause spillover to human populations, they are not a natural reservoir for Nipah. As a good sanitary practice, it is always advised to wash and disinfect hands before and after handling pigs, but this is particularly important after handling animals in at-risk areas to prevent possible exposure to the virus.

 

Human-to-human transmission of Nipah virus can occur following close contact with infected humans or their saliva, respiratory secretions or urine. This is a particularly important method of disease transmission among caregivers and family members of infected people.

 

How does Nipah affect humans?

 

Humans infected with Nipah virus can be asymptomatic (show no signs of disease) or have signs that range from mild or severe respiratory infection to fatal inflammation of the brain (i.e. encephalitis). Infected people can develop influenza-like symptoms of fever, headaches, and muscle pain. Severe cases can progress to seizures, brain inflammation, and coma in 24 to 48 hours. Typically 40 – 75% of human infections result in death, and clinical treatment is limited to supportive care. There is no vaccination or cure available. The incubation period (interval from infection to the onset of symptoms) is believed to range from 4 to 14 days, although an incubation period of 45 days has been reported.

 

For more information about Nipah in humans, see the World Health Organization (WHO) webpage.

 

How does Nipah virus affect animals?

 

Bats can contaminate dates and other collected fruit sap through their urine, feces, or saliva, and humans can become infected with Nipah virus after eating or drinking contaminated products.

 

There is currently no evidence demonstrating that Nipah has been transmitted to humans by consuming pork products, but raw tissues may still be a source of human infection. In affected and at-risk areas, Nipah virus has been found to affect the lungs and respiratory tract, brain, lymph nodes, and kidneys in infected pigs, and it is recommended these parts not be eaten. All other parts of the animal should be thoroughly cooked before consumption.  The virus is inactivated by heating at 100°C for more than 15 minutes, and is not transmitted through the consumption of well-cooked food.  

 

In general, consuming bats as wild meat poses possible serious threats to human health. Bats are not only the reservoir for Nipah virus, but potentially also for other deadly diseases that can be transmitted to humans (e.g. Ebola, rabies).

 

There is no current information available if curing meats or other methods of meat processing effectively inactivate the Nipah virus, and it is not known how long the virus may survive outside of a living host.

 

How can Nipah virus be spread through food?

 

Bats can contaminate dates and other collected fruit sap through their urine, feces, or saliva, and humans can become infected with Nipah virus after eating or drinking contaminated products.

 

There is currently no evidence demonstrating that Nipah has been transmitted to humans by consuming pork products, but raw tissues may still be a source of human infection. In affected and at-risk areas, Nipah virus has been found to affect the lungs and respiratory tract, brain, lymph nodes, and kidneys in infected pigs, and it is recommended these parts not be eaten. All other parts of the animal should be thoroughly cooked before consumption.  The virus is inactivated by heating at 100°C for more than 15 minutes, and is not transmitted through the consumption of well-cooked food.

 

In general, consuming bats as wild meat poses possible serious threats to human health. Bats are not only the reservoir for Nipah virus, but potentially also for other deadly diseases that can be transmitted to humans (e.g. Ebola, rabies).

 

There is no current information available if curing meats or other methods of meat processing effectively inactivate the Nipah virus, and it is not known how long the virus may survive outside of a living host.

 

What are good food preparation practices in Nipah-affected or at-risk areas?

 

Infectious bat saliva, urine and feces may potentially contaminate many food sources. Adhering to the following recommendations, in addition to general hygienic food preparation practices, can help prevent Nipah infections in human populations.

 

  • Boil freshly collected date palm juice and allow for cooling before drinking.
  • Thoroughly wash and peel fruits before consumption to remove any possible contamination from fruit bats.
  • Use protective coverings to prevent bat access to date palm sap and other fresh fruit products.
  • It is recommended that people in affected and at-risk areas do not hunt, dress or eat bats.
  • Avoid consuming organs that the Nipah virus has been found to affect in infected pigs, such as the lungs and respiratory tract, brain, lymph nodes, and kidneys, in affected or at-risk areas.

As a general principle to protect yourself and your family from any zoonotic disease, do not handle, slaughter, dress, sell, prepare or consume any meat or animal products which originate from an animal that is sick or that has died from unknown causes. For similar reasons, raw meat or uncooked dishes based on the blood of animals should not be consumed. Excluding bats, meat from healthy wildlife and livestock that is safely prepared and cooked remains safe to eat.

 

General good food preparation practices include:

 

  • Wash hands with soap before and after handling food (raw meat or fruits).
  • Wash hands with soap between handling raw food and cooked or ready-to eat food.
  • Keep raw meat separate at all times from cooked or ready-to-eat foods.
  • Keep utensils and surfaces (e.g. chopping boards, knives and plates) used to prepare raw meat and those to prepare fruit separate at all times and separate from those used for other foods.
  • Promptly wash with soap and disinfect all surfaces and utensils that have been in contact with fruits or raw meat.

For more information regarding food safety and foodborne diseases, see the US Centers for Disease Control and Prevention webpage on food safety, the WHO Food Safety webpage and the joint FAO/WHO Viruses in Food meeting report.

 

What specific precautions should be taken by individuals who have close contact with pigs in Nipah-affected areas?

 

Pigs infected with Nipah virus may not show any signs of sickness, but are still able to spread the disease.  It is recommended to wear personal protective equipment (PPE) in Nipah-affected areas as a common practice while handling live or dead animals, their tissues, or while slaughtering animals. Good PPE includes gloves, a cover for the mouth and nose, goggles, and other long protective clothing. Use of PPE is especially important if pigs have been reported ill in a nearby region, as the risk of disease spread to humans may be greater. Follow good biosecurity practices on pig farms and in slaughterhouses, as indicated in the FAO Frequently Asked Questions on Pig Biosecurity and Disease Reporting, to prevent the possible spread of disease.

 

One of the most important biosecurity measures for Nipah affected areas is to prevent bat access to pig farms and slaughterhouses, e.g. through roofing, shielding of feeding areas, and applying wire screens to open-sided pig sheds. Nets can also be applied to higher openings of buildings if these are used for natural sources of ventilations. Run-off from the roof may contain bat urine and/or feces and should be prevented from entering pig farms.

 

As a general principle, it is recommended to take caution and wear personal protective equipment (PPE) when working with any sick pigs.

 

What specific measures should be taken if Nipah is suspected in local pig populations?

 

As a disease that has the potential to cause devastating harm to public health as well as local economies and livelihoods, the occurrence or suspect case of Nipah should be immediately reported to the local animal health officer or appropriate animal health authority. Control measures to prevent the spread of Nipah virus focus on immediate eradication through mass culling of infected and contact pigs. Carcasses should be properly and safely disposed of as soon as possible to reduce further health risks to human and animal populations. Recommended methods of carcass disposal include burial and burning, and animal health authorities should be contacted for appropriate guidance and support.

 

After carcasses have been properly disposed, the remaining secretions of the infected pigs remain as a possible source of human infection. Any tools, equipment, and holding facilities should be washed with soap and water, and properly disinfected. The virus is susceptible to most disinfectants, including common household bleach, which is usually very inexpensive and accessible. Bleach should be diluted to a 1:10 ratio, which can be achieved by mixing 250mL (1 cup) of household bleach to 2250mL (9 cups) water.   

 

For more information on proper carcass disposal, see the FAO manual on Procedures for Disease Eradication by Stamping Out, Part 2.

 

Where can I get more information about Nipah?

 

Where can I get more information about biosecurity and disease control?