Nipah Virus

Nipah virus (NiV) infection is a newly emerging zoonosis, a disease which can be transmitted to humans from animals, that causes severe rapid, fatal respiratory and neurologic disease in both humans and animals. The natural host of the virus are fruit bats of the Pteropodidae Family, and the Pteropus genus but they are symptomless carriers… The organism which causes Nipah Virus encephalitis is an RNA or Ribonucleic acid virus of the family Paramyxoviridae, genus Henipavirus, and is closely related to Hendra virus.

Nipah Virus is not an airborne transmission infection and can affect those who come in direct contact with contaminated bodies. Infection with the Nipah virus is associated with encephalitis (inflammation of the brain). After exposure and an incubation period of 5 to 14 days, common signs and symptoms of NiV are headache, fever, nausea, dizziness, disorientation, drowsiness and mental issues such as confusion. These symptoms can last up to 7-10 days. Watching out for respiratory illness during the early stages is also a must. These signs and symptoms can progress to coma within 24-48 hours. Some patients have a respiratory illness during the early part of their infections, and half of the patients showing severe neurological signs showed also pulmonary signs. It has a mortality rate in humans of up to 75 per cent.

Before 1998 there had been no reports of a disease of wildlife, domestic animals or humans that would subsequently be considered infection with the Nipah virus.  Pigs were the intermediate hosts during this outbreak of disease that took place in Kampung Sungai Nipah, Malaysia. Nipah virus infection got its name from a village in Malaysia where the person from whom the virus was first isolated succumbed to the disease. The virus has been listed in the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code and must be reported to the OIE (OIE Terrestrial Animal Health Code).  The virus is present in bat urine and potentially, bat faeces, saliva, and birthing fluids.

There is no vaccine for either humans or animals. The primary treatment for human cases is intensive supportive care. Treatment is focused on managing fever and neurological symptoms. Ribavirin may alleviate the symptoms of nausea, vomiting, and convulsions. The most crucial way of limiting future human disease is early recognition of illness in intermediate animal hosts.  can be transmitted person-to-person, standard infection control practices and proper barrier nursing techniques are important in preventing hospital-acquired infections (nosocomial transmission). Detection is another issue with NiV and anyone who feels the symptoms should get tested thoroughly by a recognized facility.

Due to the migratory habit of the locally abundant fruit bats in South Asia, Nipah outbreaks occur more in this region. Previous outbreaks have been reported in India, Bangladesh, Thailand, Cambodia, the Philippines, Laos and Malaysia. Before the outbreak in Kerala in 2018, India had two outbreaks in West Bengal, in Siliguri in 2001 and in Nadia in 2007. Both these outbreaks are thought to have been caused by infected bats.

In fact, there are two distinct strains of the virus; NiVM refers to the strain found in Malaysia and NiVB is the strain found in Bangladesh. NiVb is thought to be more pathogenic than NiVM because of its quicker transmission pattern and higher mortality rate. Antibodies for the virus have been found in bats in Indonesia, Thailand and Timor-Leste indicating the presence of the virus in these countries but without any spillover into human populations.

Epidemiologist says that the emergence of bat-related viral infections can be attributed to the loss of the animal’s natural habitats. Another direct consequence of habitat loss and climate change is nutritional stress through the loss of food resources that made bats closer to urban areas. According to a study in Malaysia, rapid urbanization of bat-rich rainforests contributed to the emergence of Nipah virus there: the regions most adversely affected were those that suffered from maximum deforestation. Forest fragmentation and hunting bats for food also bring them closer to humans and is often an important cause of disease transmission, says Rohit Chakravarty who studies bats in India.

According to a report by WHO “As the flying fox habitat is destroyed by human activity, the bats get stressed and hungry, their immune system gets weaker, their virus load goes up and a lot of virus spills out in their urine and saliva.” Hunger and stress in fruit bats resulted in the fast multiplication of Nipah viruses inside their bodies. Now, overpopulated Nipah viruses inside fruit bats spilt out from their excreta and saliva and reached humans to kill them.

The WHO report further says that seasonal variations may also have a role in virus shedding by flying foxes due to stressful physiological conditions. Evidence of seasonal preference for transmission of the Nipah virus was found in a study conducted in Thailand. The period between April and June is understood to be the suitable time for the Nipah virus outbreak with the month of May showing the highest infection.

Following are some preventive measures:-

  1. We can protect ourselves by maintaining good personal hygiene and washing our hands after being out in public and before eating.
  2. Doctors also recommend avoiding drinking any unpasteurized juices in regions with Nipah outbreaks and fruit that have fallen from trees or show any signs of bites.
  3. Fruit should be washed thoroughly, peeled or cooked before eating.
  4. Do not consume date palm sap as the chances of it being contaminated are very high. Fruit bats are very likely to visit the date palm trees and lick the sap.
  5. Domestic animals can also be the carriers of NiV as fruit bats often drop partially eaten fruits which they can consume. Try to keep them indoors and feed them yourself or if there’s a chance of them being infected, keep your distance from them and get them treated.
  6. Don’t climb trees where bats may have left their saliva or secretions. Physical barriers can be put in place in order to prevent bats from accessing and contaminating palm sap.
  7. In the case of animals, wire screens can help prevent contact with bats when pigs are raised in open-sided pig sheds. Run-off from the roof should be prevented from entering pig pens.

Don’t panic! It’s always important to be aware and take preventive measures. There is a complex interaction between human health, animal health and the health of ecosystems and the environment. Only by understanding and caring for all three will we be able to truly predict and control the next spillover epidemic. Instead of culling Bats, we need to understand them better and recognize their connection to us. Also, we need to remember, that as we exert a greater effect on our surrounding ecosystems and the environment, we need to be aware that it just might just come back to us.