Outbreak of Nipah virus (NiV)

Nipah virus (NiV) first emerged in India with major outbreaks in West Bengal (Siliguri 2001, Nadia 2007) near the Bangladesh border, causing significant fatalities, linked to fruit bats and contaminated date palm sap. After a decade, it re-emerged in Kerala in 2018, marking a new geographical area and prompting robust public health responses, with *sporadic outbreaks continuing in Kerala (2019, 2021, 2023, 2024, 2025). These recurrent events highlight NiV as a persistent *zoonotic threat in India, requiring continuous surveillance and control measures. 

  Prevention:

• Avoid the lip- smacking fresh date palm sap, better known as khejur rosh. This refreshing drink is also a favorite of fruit bats, which can contaminate the liquid with their saliva or other body fluids and transmit it to humans.

• Health experts also cautioned people to wash fruits properly before consuming them, or peel them to be on the safe side, as these nocturnal mammals love to take a bite on fruits hanging on trees.

“This is a peak season for date palm sap, which many consume on a regular basis. For many city people who visit rural Bengal on short vacations, they relish this sap. For now, they must avoid consuming this raw sap as it is a potential source of Nipah virus,” cautioned Paediatrician Professor Prabhas Prasun Giri of the Institute of Child Health. “But our patali or nolen—that is prepared after an intense heating process of this raw sap, is safe to consume,” he added, while the fresh raw sap is not available in Kolkata, processed products like gur, or nolen gur are available in city markets. This is the time of year when sweets laden with Nolan gur are in high demand.

In fact, in most of the previous Nipah outbreaks in India, including Kerala, Bengal, and neighbouring Bangladesh, the primary source of infection was traced to fresh palm sap contaminated by fruit bats. The fresh date sap is collected in a pot that is hung overnight on the tree.

“ Fresh date sap can be a potential source of Nipah infection as it may contain the virus if it is contaminated by bats during the process of collection. Hence, people should avoid it now,” said infection disease specialist Arkendu Basu of Mission Hospital, Durgapur.

“These bats feed on different types of fruits. Therefore, we need to be very careful while eating fruits. Proper washing and peeling of fruits can be a good step to remain safe, while avoiding fruits that show signs of bat bites, and not consuming fruits that fall on the ground, as there is a chance of that these were bitten by bats. The season for Nipah outbreaks in India is mostly between December and May,” said Bhaskar Narayan Choudhuri, Chief Microbiologist of Peerless Hospital.

In fact, leftover fruits from these bats that fall on the ground are a source of infection for animals like pigs and horses that consume them, making them intermediate hosts, while no case of Nipah transmission from these animals was reported in India. Nipah infection in humans from these animals was documented in Malaysia, Singapore, and the Philippines.

Experts said the virus can survive in raw date sap or fruits for several days, making these potential modes of transmission. However, the condensed products or the dry date, which are processed, do not carry the threat.

Avoid:

1. Fresh date sap due to high chances of contamination by bats.

2. Fruits with signs of bat bites

3. Fruits fallen from the tree

Safe: Consume gur, patali, nolen gur, sweets made, Dry dates

Precautions:

1. Cleanse and wash fruits thoroughly

2. Peel fruits before consuming

3. Discard fruits that show signs of being attacked by a bat

4. Wash hands and maintain hand hygiene.

*Zoonotic diseases are infectious illnesses caused by bacteria, viruses, parasites, or fungi that spread from vertebrate animals to humans

*A sporadic outbreak refers to

a disease or infection that occurs rarely, irregularly, and in scattered locations without a specific geographic concentration