Nipah virus (NiV) is a highly pathogenic zoonotic virus belonging to the genus Henipavirus within the family Paramyxoviridae, and it has emerged as one of the most concerning viral threats to global public health in the 21st century. Since its initial identification in 1998-1999 during a large outbreak among pig farmers and abattoir workers in Malaysia and Singapore, where it caused over 265 cases with a case fatality rate of approximately 40%, NiV has caused recurrent outbreaks in Bangladesh and India, with substantially higher case fatality rates ranging from 40% to over 90%. The virus has been classified as a Category C priority pathogen by the US National Institute of Allergy and Infectious Diseases, a Blueprint priority disease by the World Health Organization (WHO), and a priority pathogen by the Coalition for Epidemic Preparedness Innovations (CEPI), reflecting the widespread recognition of its pandemic potential and the urgent need for medical countermeasures. NiV infection in humans manifests as a severe febrile illness that can progress to encephalitis, respiratory distress, and vasculitis, with a high rate of neurological sequelae among survivors and the potential for relapsed or late-onset encephalitis months to years after initial infection.
The natural reservoir of NiV is fruit bats of the Pteropus genus, commonly known as flying foxes, which are widely distributed across South Asia, Southeast Asia, and parts of East Asia, including southern China. The virus is transmitted from bats to humans through direct contact with infected bats or their bodily fluids, consumption of contaminated food products such as raw date palm sap (a well-documented transmission route in Bangladesh), or contact with intermediate animal hosts such as pigs. Importantly, NiV is also capable of human-to-human transmission through close contact with infected individuals, particularly in healthcare settings and household environments, as demonstrated by numerous nosocomial outbreaks in Bangladesh and India, which amplifies the public health risk and underscores the need for robust infection prevention and control measures.
The global epidemiology of NiV has evolved significantly since its initial emergence, with an increasing frequency of outbreaks and an expanding geographic range that raises concerns about the virus's pandemic potential. Bangladesh has experienced annual NiV outbreaks since 2001, primarily during the winter months and linked to the consumption of raw date palm sap contaminated by fruit bats, with human-to-human transmission accounting for a significant proportion of cases in many outbreaks. India has experienced several outbreaks, most notably in Kerala state in 2018 and 2019, where the virus caused clusters of cases with high mortality and demonstrated efficient human-to-human transmission in healthcare settings.
The factors driving the emergence and spread of NiV are complex and multifaceted, encompassing environmental, ecological, agricultural, and socioeconomic dimensions. Deforestation and habitat loss have forced fruit bat populations into closer proximity with human settlements, increasing the frequency of human-bat interactions and the potential for viral spillover. Agricultural intensification, particularly the establishment of commercial pig farms in areas where fruit bats are endemic, created the conditions for the initial Malaysian outbreak, as pigs served as amplifying hosts that transmitted the virus to humans. Climate change may also play a role by altering the geographic distribution and migratory patterns of fruit bat populations, potentially expanding the range of NiV-endemic areas. The growing volume of international air travel and trade further increases the risk of global dissemination, as an infected individual traveling from an endemic region could introduce the virus to new areas with susceptible populations and potentially trigger outbreaks. The absence of licensed vaccines or specific antiviral treatments for NiV further amplifies the public health threat, as outbreak response currently relies on non-pharmaceutical interventions such as case isolation, contact tracing, and infection prevention and control measures, which may be insufficient to contain large-scale outbreaks, particularly in settings with limited healthcare infrastructure.
China represents a country at particularly high risk for NiV introduction and potential outbreak, due to a convergence of ecological, geographic, and socioeconomic factors. First, southern China, including Yunnan, Guangxi, Guangdong, and Hainan provinces, lies within the geographic range of Pteropus fruit bats, which are known to be susceptible to NiV infection and could serve as natural reservoirs. Ecological studies have identified NiV-neutralizing antibodies or NiV-related viral nucleic acids in fruit bat populations in neighboring countries, and it is plausible that similar viruses circulate in bat populations in southern China, although systematic surveillance has been limited.
DOI
10.1007/s11684-026-1249-4