Situation at a glance
Between 17 May and 12 July 2025, the Information and Public Relations Department, Government of Kerala informed through a series of official press releases about four confirmed cases, including two deaths, due to Nipah virus (NiV) infection in two districts of Kerala State.
NiV infection is a bat-borne disease transmitted to humans through infected animals (such as bats or pigs), contaminated food or, less commonly, through close contact with infected individuals.
Since 1998 NiV outbreaks have been reported in Bangladesh, India, Malaysia, the Philippines, and Singapore.
In India, NiV infections have occurred multiple times since 2001 with outbreaks in West Bengal State in 2001 and 2007, and in Kerala State regularly since 2018.
Since 2018, Kerala has reported a total of nine NiV outbreaks. While the state has a strong healthcare system and improved infection control measures since 2023, it is advisable to maintain strong preparedness and surveillance efforts while ensuring continued care for patients.
At the same time, States that may be at risk should be encouraged to continue strengthen their detection systems and response capacities.
With no licensed vaccine or treatment available, public health efforts should focus on raising awareness of risk factors and promoting preventive measures to reduce exposure to the virus, and on early case detection supported by adequate intensive supportive care.
Currently, the risk of international disease spread is considered low. There is no evidence of human-to-human transmission of NiV internationally in this event.
Description of the situation
Between 17 May and 12 July 2025, the Information and Public Relations Department, Government of Kerala through a series of official press releases informed about four confirmed NiV cases, including two deaths, due to NiV infection from two districts of Kerala State.
Of the four cases, two were reported from Malappuram and two from Palakkad district.
This marks the first-ever outbreak in Palakkad District.
Of the four cases, one case was reported in May (with symptom onset in April) and three in July with symptom onset June (two cases), and July (one case).
The first patient was an adult woman from Malappuram district with symptom onset on 25 April. The patient was admitted in critical condition to a local hospital in Malappuram with fever, cough, and respiratory distress due to worsening of symptoms. She was transferred to intensive care on 2 May due to acute encephalitis syndrome. Samples were collected and tested positive for NiV at Calicut Medical College on 6 May. Confirmatory testing was conducted by the National Institute of Virology, Pune, and results confirmed on 8 May.
The second patient, also an adult woman from Malappuram district developed symptoms on 23 June and died on 1 July. She visited multiple healthcare facilities, before being transferred to a government medical facility, where clinical suspicion of NiV led to sample collection and laboratory testing.
The third patient is an adult woman from Palakkad district who developed symptoms on 25 June. She sought care at several healthcare facilities, before being admitted to a multi-specialty hospital, where she remains in critical condition on ventilator support. This is the first confirmed NiV case in Palakkad district.
The fourth case was an adult male also from Palakkad district, who developed symptoms on 6 July 2025. He sought initial medical care on the same day, was admitted to a private hospital on 10 July, and transferred to a multi-specialty hospital on 11 July. On 12 July, he died and was confirmed with NiV infection. This is the second confirmed case in Palakkad district.
The sources of infection of the cases remain under investigation.
None of these cases appear to be linked to each other, suggesting independent spillover events from the natural reservoir.
A significant presence of fruit bats, the known reservoir for NiV has been observed in the affected areas.
Epidemiology
NiV infection is a bat-borne zoonotic disease transmitted to humans through infected animals (such as bats or pigs), or food contaminated with saliva, urine, and excreta of infected animals. It can also be transmitted directly from person to person through close contact with an infected person (although less common). Fruit bats or flying foxes (Pteropus species) are the natural hosts for the virus.
The incubation period ranges on average from 4 to 14 days. However, an incubation period of up to 45 days has been reported once. Laboratory diagnosis of a patient with a clinical history of NiV infection can be made during the acute and convalescent phases of the disease by using a combination of tests. The main tests used are Reverse Transcription Polymerase Chain Reaction (RT-PCR) from bodily fluids and antibody detection via enzyme-linked immunosorbent assay (ELISA).
Symptoms range from acute respiratory infection and fatal encephalitis. Further information about NiV infection can be found here.
The case-fatality rates in outbreaks across Bangladesh, India, Malaysia, and Singapore typically range from 40% to 100%, depending on local capabilities for early detection and clinical management. Although candidate products are in development, there are no licensed vaccines or therapeutics available for the prevention or treatment of NiV infection.
Public health response
Several public health measures have been implemented by local authorities including:
-- The Kerala state health minister chaired an emergency meeting to assess the situation and confirmed that preventive measures have been strengthened in accordance with the established NiV protocol.
-- As of 17 July, contact tracing is intensively implemented. A total of 723 individuals have been identified as contacts of confirmed Nipah virus (NiV) cases across several districts: Palakkad (394), Malappuram (212), Kozhikode (114), Ernakulam (2), and Thrissur (1).
-- Based on an in-depth investigation, Kerala health authorities have released route maps for the movement of three confirmed NiV cases reported in July, to trace potential community exposures.
-- Alerts have been issued by health authorities in Kozhikode, Malappuram, and Palakkad districts. In response, 26 special teams were deployed to carry out contact tracing, monitor symptoms among contacts and inform the public.
-- Additionally, a special alert has been issued to hospitals in Kannur, Kozhikode, Malappuram, Palakkad, Thrissur and Wayanad districts, instructing them to remain vigilant and promptly report any suspected cases with NiV symptoms.
-- The public has been advised to avoid non-essential visits to healthcare facilities to minimize the risk of transmission.
-- WHO is closely coordinating with the National Centre for Disease Control on One Health and capacity building for high threat pathogens including NiV.
WHO risk assessment
As of July 2025, a total of nine NiV outbreaks have been reported in Kerala State. Recent case numbers reported in Kerala State are consistent with trends observed in previous years and are therefore not entirely unexpected.
However, they continue to highlight a localized risk associated with NiV in that area.
At this time, the overall risk to the broader national and regional population remains low.
The first outbreak was reported in 2018 (23 cases including confirmed and probable; CFR: 91%), followed by subsequent outbreaks in 2019 (a single case who survived), 2021 (one case; CFR: 100%), 2023 (six cases including two deaths; CFR: 33%), 2024 (two cases; CFR 100%), and 2025.
So far in 2025, four confirmed cases of NiV, have been reported, all from Kerala State, with the symptom onset in April (one case), June (two cases) and July (one case).
These recurrent spillover events highlight the ongoing risk of NiV in Kerala. In addition, studies indicated that fruit bats tested positive for NiV antibodies in several other Indian states, suggesting that NiV infection may potentially emerge in other States.
Kerala State has a robust healthcare system. While nosocomial transmission was confirmed during the 2023 outbreak, the Infection Prevention and Control (IPC), and waste management practices have since been strengthened and audited.
The sources of infection for the 2025 cases are yet to be confirmed.
WHO advice
In the absence of a vaccine or licensed treatment available for NiV disease, the only way to reduce or prevent infection in people is by raising awareness of the risk factors and supporting people with measures they can take to reduce exposure to the virus.
Case management should focus on the delivery of timely, supportive care and be supported by a good laboratory system. Intensive supportive care is recommended to treat severe respiratory and neurologic complications.
Public health educational messages should focus on:
-- Reducing the risk of bat-to-human transmission
-- Efforts to prevent transmission should first focus on decreasing bat access to date palm sap and other fresh food products. Freshly collected date palm juice should be boiled, and fruits should be thoroughly washed and peeled before consumption. Fruits with signs of bat bites should be discarded. Areas where bats are known to roost should be avoided.
-- Reducing the risk of human-to-human transmission.
-- Close unprotected physical contact with NiV-infected people should be avoided. Regular hand washing should be carried out after caring for or visiting sick people.
-- Controlling infection in health care settings
-- Health-care workers caring for patients with suspected or confirmed infection, or handling specimens from them, should implement standard infection control precautions at all times.
-- As human-to-human transmission has been reported, in particular in health-care settings, contact and droplet precautions should be used in addition to standard precautions. Airborne precautions may be required in certain circumstances.
-- Samples taken from people and animals with suspected NiV infection should be handled by trained staff working in suitably equipped laboratories.
-- WHO does not recommend any travel and/or trade restrictions toward India based on the currently available information.
Further information
- Department of Public Relations, Government of Kerala. https://www.prd.kerala.gov.in/ml/node/307801
- Directorate of Health Services, Kerala. IDSP Daily Report 1 August 2025. Thiruvananthapuram: DHS Kerala; 2025. Available from: https://dhs.kerala.gov.in/wp-content/uploads/2025/08/IDSP-Daily-Report-01.08.2025.pdf
- Information & Public Relations Department, Government of Kerala 29 May 2025. Relief in Nipah: A total of 114 people tested negative after the quarantine period of all those on the contact list was over. Available from: https://prd.kerala.gov.in/index.php/ml/node/300946
- Public Relations Department, Government of Kerala. Nipah virus infection updated official report, May 2025. Thiruvananthapuram: Government of Kerala; 2025 [cited 2025 May 12]. Available from: https://prd.kerala.gov.in/ml/node/297643
- Public Relations Department, Government of Kerala. Nipah virus infection updated official report, May 2025. Thiruvananthapuram: Government of Kerala; 2025 [cited 2025 May 12]. Available from: https://prd.kerala.gov.in/ml/node/297971
- Department of Public Relations, Government of Kerala. Confirmed Nipah Cases in Malappuram and Palakkad Districts [press release]. Thiruvananthapuram: DPR Kerala; 4 July 2025. Available from: https://www.prd.kerala.gov.in/ml/node/307104.
- Department of Public Relations, Government of Kerala. Nipah Virus Infection: Health Department Intensifies Surveillance and Containment Measures [press release]. Thiruvananthapuram: DPR Kerala; 2 July 2025. Available from: https://www.prd.kerala.gov.in/ml/node/306853.
- Department of Public Relations, Government of Kerala. Health Department Issues Nipah Virus Alert in Palakkad and Malappuram [press release]. Thiruvananthapuram: DPR Kerala; 1 July 2025. Available from: https://www.prd.kerala.gov.in/ml/node/306653.
- Department of Public Relations, Government of Kerala. A total of 499 people are on the Nipah contact list; 10 July. https://www.prd.kerala.gov.in/ml/node/307528
- Department of Public Relations, Government of Kerala. A total of 609 people are on the Nipah contact list in the state; 14 July https://www.prd.kerala.gov.in/ml/node/307873
- Department of Public Relations, Government of Kerala; 17 July: https://www.prd.kerala.gov.in/ml/node/308413
- Department of Public Relations, Government of Kerala. High-level meeting convened in connection with the spread of Nipah virus [press release]. Thiruvananthapuram: DPR Kerala; 11 July 2025. Available from: https://prd.kerala.gov.in/ml/node/307707
- World Health Organization, Regional Office for South-East Asia. Regional strategy for the prevention and control of Nipah virus infection: 2023 2030. New Delhi: WHO SEARO; 2023. Available from: https://www.who.int/publications/i/item/9789290210849
- World Health Organization. Technical brief: Enhancing readiness for a Nipah virus event in countries not reporting a Nipah virus event: interim document. Geneva: WHO; 2024 Feb. Available from: https://www.who.int/publications/i/item/9789290211273
- World Health Organization. Nipah virus [Fact sheet]. Geneva: WHO; 2018. Available from: https://www.who.int/news-room/fact-sheets/detail/nipah-virus
- 10th edition, Epidemiological Bulletin WHO Health Emergencies Programme WHO Regional Office for South-East Asia , 21 May 2025 Reporting period: 05 - 18 May 2025 Available from: https://www.who.int/southeastasia/publications/i/item/9789290220831
Citable reference: World Health Organization (6 August 2025). Disease Outbreak News; Nipah virus infection – India. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON577
Source: World Health Organization, https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON577
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