Nipah virus (NiV) is a highly virulent zoonotic RNA virus in the genus Henipavirus, family Paramyxoviridae. It is a BSL-4 pathogen that causes severe disease in both humans and animals, characterized by respiratory illness and fatal encephalitis.[1] The virus was first identified in 1998 during an outbreak among pig farmers in Malaysia, and was named after Sungai Nipah, the village where the outbreak was first recognized.[1][2] The World Health Organization (WHO) has identified Nipah as a priority disease for its Research and Development Blueprint due to its epidemic potential and case fatality rate of 40–75%.[1][2][3]
Virology[edit | edit source]
Nipah virus is an enveloped, pleomorphic virus. Its genome is a single-stranded, negative-sense, non-segmented RNA molecule of approximately 18.2 kb.[4] The genome encodes six structural proteins in the order 3′-N-P-M-F-G-L-5′: the nucleocapsid (N) protein, phosphoprotein (P), matrix (M) protein, fusion (F) protein, attachment glycoprotein (G), and the large polymerase (L) protein.[4] The G protein mediates viral attachment to host cell receptors—ephrin-B2 (EFNB2) and ephrin-B3 (EFNB3)—while the F protein facilitates fusion between the viral envelope and the host cell membrane.[4][5] The widespread expression of ephrin-B2 on endothelial cells and neurons explains the systemic nature of henipavirus infections and the tropism of NiV for the brain and blood vessels.[4]
Phylogenetic analyses have identified two major clades: the NiV-MY clade, comprising isolates from Malaysia and Cambodia, and the NiV-BD clade, which includes isolates from Bangladesh and India.[4]
Transmission[edit | edit source]
Fruit bats of the genus Pteropus (family Pteropodidae) are the natural reservoir of Nipah virus. The virus is shed in bat saliva, urine, and feces, and infection does not appear to cause disease in the bats themselves.[1][6][2]
Transmission to humans occurs through several pathways. Consumption of raw date palm sap contaminated by bat saliva or urine is a major transmission route in Bangladesh and India.[1][2][3] In the Malaysian outbreak, pigs served as amplifying hosts, and human infection occurred through direct contact with infected pigs or their bodily fluids.[1][2][6] Human-to-human transmission has also been reported following close contact with an infected person or their bodily fluids, including respiratory droplets, urine, or blood, particularly among caregivers and healthcare workers in Bangladesh and India.[1][2][6]
Clinical features[edit | edit source]
The incubation period for Nipah virus infection ranges from 3 to 14 days, with rare cases of up to 45 days reported.[1][6] Infection can be asymptomatic or present as acute respiratory illness, fatal encephalitis, or a combination of both.[1][2]
Initial symptoms are often non-specific and include fever, headache, myalgia, vomiting, and sore throat.[6][2] These may progress to dizziness, drowsiness, altered consciousness, and other neurological signs of acute encephalitis. Encephalitis and seizures occur in severe cases and can progress to coma within 24 to 48 hours.[6][2] Some patients develop atypical pneumonia or acute respiratory distress syndrome.[6][7] Most people who survive make a full recovery, but long-term neurological conditions have been reported in approximately 1 in 5 survivors.[1] Relapsed and late-onset encephalitis are also recognized features of the disease.[2][8]
The case fatality rate of Nipah virus infection is estimated at 40–75%, varying by outbreak depending on surveillance and clinical management.[1][2][3]
Diagnosis[edit | edit source]
Laboratory diagnosis of Nipah virus infection relies primarily on molecular detection by RT-PCR and serological assays such as ELISA.[8][9] RT-PCR is considered the gold standard and can be performed on nasopharyngeal or oropharyngeal swabs, cerebrospinal fluid, urine, and serum samples.[8][9] A combination of clinical history, serology, and appropriate sample type remains essential for accurate diagnosis, and high biocontainment is required for sample handling.[8]
Treatment[edit | edit source]
There are currently no approved drugs or vaccines that specifically target Nipah virus infection.[1][2][8] Primary treatment is symptomatic and supportive care, with early intensive supportive care recommended to manage severe respiratory and neurological complications and improve survival.[1][6][2]
Several therapeutic candidates have shown potential in limited or preclinical studies, including ribavirin, remdesivir, and favipiravir.[8][10] A monoclonal antibody (m102.4) is available under compassionate use in Australia.[8] Multiple vaccine platforms are in preclinical and early-phase development, including mRNA, vector-based, and subunit vaccines, but none are yet licensed.[8]
Epidemiology[edit | edit source]
Since its discovery, Nipah virus outbreaks have been reported in Malaysia, Singapore, Bangladesh, India, and the Philippines.[3][2] The initial outbreak in Malaysia (1998–1999) involved pig-amplified transmission; subsequent outbreaks in Bangladesh and India have been characterized by bat-driven spillover and limited human-to-human transmission, particularly in household and hospital settings.[3][2][6]
In Bangladesh, seasonal outbreaks occur annually during the winter months, often linked to consumption of raw date palm sap.[2] In India, outbreaks have been more sporadic, occurring in West Bengal in 2001 and 2007, and repeatedly in Kerala since 2018.[3][2] As of 2026, Kerala has reported multiple outbreaks, including a 2023 outbreak in Kozhikode district with six cases and two deaths (case fatality ratio 33.33%).[7][3] The Philippines experienced an outbreak of equine-to-human transmission in 2014.[6][2]
Prevention[edit | edit source]
No licensed vaccine is currently available for Nipah virus.[1][8] Prevention relies on reducing exposure to the virus. Recommended measures include avoiding contact with bats and pigs, particularly sick or dead animals; refraining from entering bat roosts or touching environments potentially contaminated by bat excrement; avoiding consumption of raw date palm sap or fallen fruits; and thoroughly washing and peeling fruits before consumption.[6][2] In healthcare settings, standard, contact, and airborne precautions are critical, as transmission has occurred in healthcare settings.[8]
History[edit | edit source]
The first recognized outbreak of Nipah virus occurred in 1998–1999 among pig farmers in Malaysia and Singapore. Epidemiological investigations revealed that fruit bats of the genus Pteropus transmitted the virus to pigs, which subsequently infected farmers and slaughterhouse workers in close contact with infected pigs.[2][6] No further outbreaks have been recorded in Malaysia or Singapore since that time.[2] Since 2001, outbreaks have occurred in Bangladesh, India, and the Philippines, with evidence of the virus in Pteropus bats widely reported across South and Southeast Asia.[2][3]
See also[edit | edit source]
References[edit | edit source]
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 "Nipah virus infection". World Health Organization. Retrieved 2026-11-05.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 "Nipah Virus Infection Frequently Asked Questions" (PDF). National Institute for Communicable Diseases (South Africa). January 2026. Retrieved 2026-11-05.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "Nipah Virus Infection – India". World Health Organization South-East Asia. Retrieved 2026-11-05.
- ↑ 4.0 4.1 4.2 4.3 4.4 "Genus: Henipavirus". International Committee on Taxonomy of Viruses. Retrieved 2026-11-05.
- ↑ "Nipah virus in the era of global connectivity: molecular evolution, transmission risk, and preparedness strategies". Virus Genes. doi:10.1007/s11262-026-02273-4. Retrieved 2026-11-05.
- ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 "Nipah Virus Infection". Centers for Disease Control, Taiwan. Retrieved 2026-11-05.
- ↑ 7.0 7.1 "Clinico-epidemiological presentations and management of Nipah virus infection during the outbreak in Kozhikode district, Kerala state, India 2023". Journal of Medical Virology. 96 (3): e29559. March 2024. doi:10.1002/jmv.29559. Retrieved 2026-11-05.
{{cite journal}}: CS1 maint: article number as page number (link) - ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 "Nipah Virus: What Clinicians Need to Know". NETEC. 2025-07-22. Retrieved 2026-11-05.
- ↑ 9.0 9.1 "Nipah virus transmission: a persistent threat to public health demanding rapid diagnosis, innovative therapeutics, vigilance, and research progress". Annals of Medicine and Surgery. 86 (5): 2370–2372. May 2024. doi:10.1097/MS9.0000000000001747. Retrieved 2026-11-05.
- ↑ "Advancing the frontiers: Revolutionary control and prevention paradigms against Nipah virus". Open Veterinary Journal. 13 (9): 1056–1070. 2023-09-30. doi:10.5455/OVJ.2023.v13.i9.1. Retrieved 2026-11-05.