NCCID Disease Debriefs provide Canadian public health practitioners and clinicians with up-to-date reviews of essential information on prominent infectious diseases for Canadian public health practice. While not a formal literature review, information is gathered from key sources including the Public Health Agency of Canada (PHAC), the World Health Organization (WHO) and peer-reviewed literature.
This disease debrief was prepared by William To-Dang. Questions, comments, and suggestions regarding this debrief are most welcome and can be sent to nccid@umanitoba.ca.
What are Disease Debriefs? To find out more about how information is collected, see our page dedicated to the Disease Debriefs.
Questions Addressed in this debrief:
- What are important characteristics of Nipah virus?
- What is happening with current outbreaks of Nipah virus?
- What is the current risk for Canadians from Nipah virus?
- What measures should be taken for a suspected Nipah virus case or contact?
What are important characteristics of Nipah virus?
Cause
Orthohenipavirus nipahense (Nipah virus, hereafter NiV) is a negative sense, single-stranded RNA genome virus belonging to the genus Henipavirus within the Parmyxoviridae family. It is a highly fatal disease, known to cause severe neurologic disease and respiratory disease. NiV was first identified in swine and people who interacted with infected swine, but has now been identified in cats, dogs, goats, horses and is known to naturally occur in certain fruit bat types. There are three main modes of transmission:
- Contact with infected animals
- Consumption of food (commonly raw dates, palm juice and fresh fruit) contaminated with the saliva or urine of infected fruit bats
- Close contact with the bodily fluids and waste of an infected person
The virus is currently endemic to Southeast Asia, in the natural habitat of the fruit bat. However, it is considered an emerging viral agent with both epidemic and pandemic potential.
Nipah Virus: A Multidimensional Update — Faus-Cotino et al., 2024
Nipah virus: Causes — Government of Canada
Nipah Virus Disease — Government of Canada
Pathogen Safety Data Sheets: Infectious Substances – Nipah virus — Government of Canada
Signs and Symptoms
NiV infection is mild or sub-clinical in 8-15% of cases. The incubation period typically ranges from 3-14 days, with incubation taking up to 45 days in some rare instances. In a small proportion of patients, onset of illness may be delayed, and relapses after recovery from acute infection may occur.
In symptomatic cases, individuals typically present with flu-like symptoms, including:
- Headaches
- Cough
- Sore throat
- Fever and chills
- Muscle pain
- Nausea
- Vomiting
- Diarrhea
- Confusion
- Giddiness
Neurological symptoms are also common, including:
- Altered consciousness
- Drowsiness
- Dizziness
- Disorientation
In more severe cases, atypical pneumonia and acute respiratory distress can develop, which may be missed or incorrectly attributed to neurological symptoms. Neurological symptoms often overshadow respiratory symptoms at the time of presentation.
There are clinical differences between Malaysian (NiV-M) and Bangladesh (NiV-B) variants. Respiratory symptoms are observed in ~70% of NiV-B patients, but there is no significant respiratory involvement in the majority of NiV-M cases. NiV-B cases are more commonly transmitted person to person and through food-borne routes, whereas NiV-M cases tend to specifically involve pigs such as direct contact with pigs for transmission. NiV-B also has a narrower average incubation period.
Nipah virus: Symptoms and treatment — Government of Canada
Pathogen Safety Data Sheets: Infectious Substances – Nipah virus — Government of Canada
Nipah virus: pathogenesis, genome, diagnosis, and treatment — Madhukalya et al., 2025
Nipah Virus — Rathish & Nguyen, 2026
Nipah virus infection (Symptoms) — World Health Organization
Severity and Complications
Serious NiV symptoms involve the central nervous system (CNS) and include:
- inability to breathe
- low level of consciousness
- hypotonia
- areflexia
- myoclonus
- brainstem dysfunction
- cerebellar signs
The most distinct CNS manifestations are neurological signs indicating inflammation and swelling of the brain (encephalitis) – these include abnormal doll’s eye reflex, reduced level of consciousness, seizures, and pinpoint pupils. NiV disease may progress to encephalitis or meningitis, followed by coma, within 1-2 days. In fulminant illness, renal failure, gastrointestinal bleeding and multiorgan dysfunction can occur. The 2 strains differ in their mortality rates as the NiV-M strain has a 40% mortality rate, while NiV-B has a 75% mortality rate. The high lethality of NiV is attributed to its evasion of the innate immune response.
Early detection and clinical management are predictors of survival, whereas severe brainstem involvement is a predictor of death. In around 8% of survivors, there is the potential for relapse months, or even years, after initial infection. While most patients who survive acute encephalitis make a full recovery, 20% of the patients who survive acute encephalitis have lasting neurological effects: seizures and personality changes. Some other long-term neurologic effects include fatigue, ocular motor palsies, focal weakness, facial paralysis, cervical dystonia, and encephalopathy.
Nipah virus infection: A review — Aditi & Shariff, 2019
Nipah Virus Disease — Government of Canada
Nipah virus: Symptoms and treatment — Government of Canada
Pathogen Safety Data Sheets: Infectious Substances – Nipah virus — Government of Canada
Nipah virus: pathogenesis, genome, diagnosis, and treatment — Madhukalya et al., 2025
Nipah Virus — Rathish & Nguyen, 2026
Nipah virus infection – Bangladesh — World Health Organization
Epidemiology
The reservoir of Nipah virus, bats in the Pteropus genus, is distributed around coastal regions and various islands in Southeast Asia, India, the Indian Ocean and Oceania. The first NiV outbreak, where the virus was transmitted from the natural bat host species to pigs and subsequently to humans, occurred in Malaysia between 1998-1999 among pig farmers and residents of villages where pigs were farmed. There were 265 cases and 105 NiV-M-related fatalities. The second outbreak occurred in 1999 in Singapore, among abattoir workers who were handling pigs imported from the Malaysia outbreak; this outbreak involved 11 cases and 1 fatality. Subsequent outbreaks of the NiV-B strain occurred in Bangladesh and India during 2001, 2003, 2004 and 2007. There was one outbreak in the Philippines during 2014, involving equine livestock.
Since the 2001 outbreak, cases have been reported in Bangladesh on a nearly annual basis, seasonal outbreaks occurring primarily between December and May, around the time when date palm sap is harvested and when bats are more likely to move towards villages due to climate pressure. There have been 347 documented NiV cases with a case-fatality rate of 71.7%. Outbreaks have been reported in India periodically, including most recently in 2026.
Nipah Virus: A Multidimensional Update — Faus-Cotino et al., 2024
Pathogen Safety Data Sheets: Infectious Substances – Nipah virus — Government of Canada
Studying Nipah virus in pigs — Government of Canada
Nipah virus — World Health Organization
Nipah virus infection – Bangladesh — World Health Organization
Laboratory Diagnosis
Any testing relating to suspected Nipah virus must be carried out in a containment level 4 (CL4) lab to ensure proper containment. In Canada, the National Microbiology Laboratory (NML) is the only facility permitted to work with live Nipah viruses. If a sample needs testing in Canada, it is recommended to contact the 24-hour emergency line at 1-800-545-7661 to facilitate safe shipping of sample to the NML and the development of an Emergency Response Assistance Plan.
During early stages of NiV infection, reverse transcriptase-polymerase chain reaction (RT-PCR) is the gold standard for diagnosis based on its high sensitivity, high specificity and ease while performing the assay. RT-PCR involves detecting traces of viral RNA which can be done using a sample from any of the following: blood, urine, cerebrospinal fluid, or throat swabs. There are complementary tests to help confirm diagnosis such as immunohistochemistry and PCR. As vascular endothelium is the site of NiV replication, various tissues may be used for immunohistochemistry: brain, lungs, kidney, lymph nodes, and spleen.
Blood samples can also be tested for the presence of anti-NiV IgM and IgG antibodies, through interactions with purified NiV antigens in enzyme-linked immunosorbent assays (ELISA). IgM antibodies are detectable in the first week after symptom onset, typically peaking at 9 days and persisting for at least 3 months after onset of illness. IgG antibodies are detectable after the second week of illness, persisting for more than 8 months.
Nipah virus infection: A review — Aditi & Shariff, 2019
Nipah virus: For health professionals — Government of Canada
Nipah virus: a summary for clinicians — Levine et al., 2025
Nipah virus: pathogenesis, genome, diagnosis, and treatment — Madhukalya et al., 2025
Transmission
The reservoirs of NiV are the fruit bats of the genus Pteropus (flying foxes), specifically Island flying foxes (Pteropus hypomelanus). The range of hosts for transmission includes: humans, fruit bats, pigs, horses, goats, dogs and cats.
Transmission from animals to humans occurs from direct contact with contaminated body fluids or tissues of animals; with NiV, the common route is human consumption of raw date palm sap which is contaminated with the feces, urine or saliva of infected bats. Outbreaks coincide with the sap-harvesting season of December-May.
Transmission from human to human occurs from close physical interactions or direct exposure to respiratory secretions and saliva, as well as blood, urine, cerebrospinal fluid and other tissues of an infected individual. Secondary human to human transmission has been becoming more observed in the recent outbreaks around Bangladesh specifically with coughing and sneezing creating large droplets for transmission. NiV is easily spread between people in healthcare settings where:
- family and caregivers are close with infected individuals
- ventilation is poor
- overcrowding is abundant
- and there is insufficient implementation of infection, prevention and control (IPAC) measures
Pathogen Safety Data Sheets: Infectious Substances – Nipah virus — Government of Canada
Nipah virus — World Health Organization
Nipah virus infection – Bangladesh — World Health Organization
Prevention and Control
There are measures one should take if travelling or temporarily working in a region where NiV is endemic:
- Avoid contact with animals, especially bats and pigs; wear gloves and protective clothing if working in animal slaughterhouses or handling animal tissues or sick animals
- Eat and drink safely when in regions where Nipah virus is endemic (see Eat and drink safely outside Canada for more specifics)
- To handle food and drinks safely:
- protect foods and drinks from bats
- avoid food that may have come into contact with animals
- do not consume food or drink that has been potentially contaminated by animals, such as partly eaten fruits and raw date palm: sap, juice and toddy unless it has been boiled for 2 minutes
- before any consumption, rigorously wash then peel fruits;
- Keep hands away from face
- Do not share drinking or eating utensils
- Prevent contact with sick people and their body fluids
- Clean surfaces that are often touched (ex. doorknobs, counters)
- Wash hands frequently with soap and water, especially after visiting sick individuals
Control measures for workers in healthcare settings are essential. These include:
- Placing individuals with suspected or confirmed NiV cases in single-patient rooms
- Using contact and droplet precautions such as eye protection, well-fitting medical masks, fluid-resistant gowns, and examination gloves when working with patients
- During aerosol-generating situations, applying airborne precautions such as putting patients in airborne-infection isolation rooms and using fit-tested filtering facepiece respirators instead of medical masks; for relatives, caregivers and other visitors of patients, similar precautions must be exercised
Bedding and clothing should be bagged and removed, with sharps disposed in puncture-proof containers. When feasible, waste containers should be steam sterilized in an autoclave. In low-resource settings, burning or incineration can be used.
Given the nature of NiV involving animals, humans and the environment, a One Health approach is recommended for prevention and control measures. This approach should cover various sectors, practices and communities at various levels of society to cumulatively predict, prevent, identify and respond to NiV.
Nipah virus: Prevention and risks — Government of Canada
Nipah virus: a summary for clinicians — Levine et al., 2025
Nipah virus — World Health Organization
Vaccination
There is no NiV vaccine currently available. Since 2017, the virus has been repeatedly included in the WHO list of priority pathogens needing investment for developing diagnostic, therapeutic, and preventive countermeasures. It is also in the priority list of viral agents needing the development of vaccination measures in the Coalition for Epidemic Preparedness Innovations (CEPI).
Nipah Virus: A Multidimensional Update — Faus-Cotino et al., 2024
Treatment
There are no specific NiV treatments, however, early diagnosis can allow for intensive, supportive medical care and prevent deaths. Treatment should include:
- Identifying any complications (encephalitis, pneumonia, other organ damage)
- Personalizing treatment to consider the other comorbidities in a patient
- Treating patients with oxygen where appropriate
- Applying specific organ support therapies where appropriate (e.g. maintenance of airway, breathing, circulation and ventilation for pneumonia and acute respiratory failure; renal dialysis for renal failure)
- Ensuring sufficient rehydration and nutrition for fluid and electrolyte balance through constant monitoring
Nipah virus infection: A review — Aditi & Shariff, 2019
Nipah virus — World Health Organization
What is happening with current outbreaks of Nipah virus?
Bangladesh
Bangladesh has had 1 newly confirmed case in the Rajshahi Division of Northwestern Bangladesh. The case involves a middle-aged female in the Naogaon District, developing symptoms in line with NiV infection on January 21, 2026, being referred to a tertiary hospital on January 27 and then admitted January 28. The day she was admitted to hospital, the NiV surveillance team collected blood samples and throat swabs, where the patient also reported repeated consumption of raw date palm sap between January 5-20, 2026 before passing away later that day. Contact tracing of 35 persons was performed in relation to the confirmed case, with 6 symptomatic contact persons having samples taken and ultimately testing negative.
During 2025, there were four temporally unrelated fatal NiV cases between January 1 to August 29, from 4 different districts across 3 separated geographical divisions. The first 3 cases had a history of consuming raw palm sap, while the fourth case did not and had no confirmed source of infection.
Nipah virus infection – Bangladesh — World Health Organization
Nipah virus infection – Bangladesh (2) — World Health Organization
India
As of January 26, 2026, there were two confirmed NiV infection cases around West Bengal State.. Both cases developed symptoms representative of severe infection around late December 2025, being admitted to hospital in early January, 2026. The associated contacts of the cases included 190 in number, ranging from health and care workers to community persons and with all testing negative for NiV infection. There have thus been no new confirmed cases in West Bengal starting from December 2025 to date.
Between May 17, 2025, and July 12, 2025, there were 4 NiV cases including 2 fatalities. Two of the cases were reported from Malappuram, while 2 were from the Palakkad District (marking the first ever outbreak in this region). There was no connection between cases, no confirmation of sources of infection for any of the cases, and yet there have been suggestions of independent spillover events from a natural reservoir as fruit bats have been observed in the affected areas.
Nipah virus infection – India — World Health Organization
Nipah virus infection – India (2) — World Health Organization
What is the current risk for Canadians from Nipah virus?
The risk to Canadians is very low as until now there have been no official cases of NiV found in Canada nor are there fruit bat species in Canada. Additionally, there are no official Travel Health notices relating to NiV.
Those that may be working with swine around Southeast Asia who should be aware of the risks, and similarly those that are travelling to, or working temporarily in, South Asia or other regions where NiV is endemic should be cautious and knowledgeable about the prevention and control measures (see first list of recommendations under “Prevention and Control” section above).
Nipah Virus Disease — Government of Canada
Nipah virus: Prevention and risks — Government of Canada
What measures should be taken for a suspected Nipah virus case or contact?
NiV is a nationally notifiable disease, needing to be reported in both confirmed and suspected cases. If someone has travelled to an area where NiV is present and has also: developed symptoms of NiV infection; and/or has contacted someone who has had NiV, this individual must tell a health professional, also detailing where they have been travelling or living. All suspected or probable NiV cases must be reported immediately, with reports being made at any time with the 24-hour emergency line: 1-866-262-8433.
Individuals who have had contact with an infectious patient must be identified and closely monitored. Contacts should have their temperature taken every day for 3 weeks after their last exposure to the infectious patient. If a high temperature (above 38°C) presents, the individual should be tested for infection immediately, since early supportive care can prove instrumental given the lack of licenced treatment.
Nipah virus: Symptoms and treatment — Government of Canada
Nipah virus: Surveillance — Government of Canada
Immediately notifiable diseases — Government of Canada
Nipah virus: For health professionals — Government of Canada