Nipah virus (NiV) remains a major zoonotic threat due to its high mortality and potential for rapid spread.

Since its first detection in India in 2001, outbreaks have recurred intermittently, with Kerala emerging as a

hotspot in recent years. Understanding the interplay between viral reservoirs, clinical outcomes, and public

health responses is critical for strengthening preparedness and limiting future transmission.

Investigations confirmed the persistence of NiV in Pteropus medius bats, with viral RNA and antibodies

detected, alongside evidence of distinct viral lineages. Human case data revealed variability in outbreak

severity: the 2018 Kozhikode event showed high fatality and nosocomial spread, while subsequent incidents in

2019 and 2021 were rapidly contained with minimal transmission. Public health interventions, including on-

site diagnostics, strict contact tracing, and infection control, proved effective in reducing secondary spread.

Sero-surveys among contacts indicated no subclinical infections during the 2019 outbreak, highlighting the

impact of timely intervention.

Findings underscore both progress and persisting vulnerabilities in NiV management. Strengthened laboratory

capacity, rapid detection, and coordinated responses have contributed to reduced morbidity and mortality in

ability to cause severe disease in humans with a high case fatality rate. First identified during outbreaks among

pig farmers in Malaysia and Singapore in 1998–1999, NiV belongs to the genus Henipavirus within the family

Paramyxoviridae(Hauser et al., 2021). Since its discovery, the virus has been associated with sporadic but

often deadly outbreaks across South and Southeast Asia, notably in Bangladesh and India. Transmission

pathways include direct contact with infected animals, most commonly fruit bats of the genus Pteropus, as well

as human-to-human spread through close contact or exposure to bodily fluids. Clinical manifestations range

from mild, self-limiting symptoms to acute respiratory distress (ARDS) and fatal encephalitis, often with rapid

deterioration(Luby et al., 2012).

In India, NiV has demonstrated a recurrent yet geographically constrained pattern of emergence. Early

outbreaks in West Bengal in 2001 and 2007 were followed by a long period of apparent absence until the virus

Kerala’s experience with NiV has also highlighted the critical role of rapid detection, coordinated response,

and rigorous contact tracing in limiting transmission. The establishment of on-site diagnostic facilities,

deployment of molecular and serological assays, and implementation of strict infection prevention measures

have been instrumental in reducing the scale of later outbreaks. Nevertheless, these responses have been largely

reactive, triggered by the recognition of clinical cases rather than proactive identification of viral circulation in

animal hosts or early-stage human infections.

The public health challenge posed by NiV lies not only in its high lethality but also in the unpredictable nature

of its emergence. Environmental factors, changing land-use patterns, and increasing human encroachment into

bat habitats may alter spillover dynamics, complicating prediction and prevention efforts. Current

understanding of NiV ecology in India remains incomplete, with limited longitudinal data on viral prevalence

in bat populations, the frequency of asymptomatic infections in humans, and the effectiveness of different

The significance of this work extends beyond regional public health, as NiV is listed by the World Health

Organization among priority pathogens for research and development due to its epidemic potential and absence

of licensed vaccines or specific antiviral therapies(Madhukalya et al., 2025). Understanding how local

epidemiology, reservoir ecology, and response capacity interact to shape outbreak outcomes in Kerala can

inform not only state and national preparedness but also global strategies for managing high-consequence

zoonotic threats. Through this comprehensive analysis, the study seeks to provide evidence-based

recommendations to strengthen early detection, optimize containment, and reduce the human toll of future NiV

events.

This research employed a descriptive, multi-source design, drawing upon data from confirmed Nipah virus

(NiV) outbreaks in Kerala between 2018 and 2023. The study integrated findings from human case

investigations, wildlife reservoir surveillance, and sero-epidemiological surveys of close contacts.

Human case data were obtained from outbreak reports, clinical studies, and public health records. Confirmed

cases were identified through laboratory testing using real-time reverse transcriptase polymerase chain reaction

(qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) for NiV-specific IgM or IgG antibodies.

Information collected included demographic characteristics, clinical presentation, laboratory findings,

transmission routes, and outcomes.

Bat surveillance involved targeted sampling in locations linked to human cases. Pteropus medius and Rousettus

leschenaultii bats were captured using mist nets set near roost sites or feeding areas. Biological specimens

samples were collected under aseptic conditions, and sera were tested for NiV-specific IgM and IgG

antibodies. Exposure histories were recorded to classify participants into high- and low-risk categories.

Data from all sources were collected and analysed to identify patterns in viral occurrence, transmission, and

clinical outcomes. Descriptive statistics summarized demographic, clinical, and laboratory findings, while

comparative analysis examined trends across different outbreak years. This integrative approach allowed for a

comprehensive assessment of NiV epidemiology and public health responses within the Kerala context.

spotlight. Investigations confirmed Pteropus fruit bats as the source and documented clear human-to-human

transmission, with 16 fatalities among 18 reported cases. This event emphasized the value of a One Health

insight into the spectrum between symptomatic and subclinical infections and highlighted the effectiveness of

containment measures and contact tracing(Ramachandran et al., 2022).

In Siliguri, West Bengal 2001 the outbreak involved 45 cases and 16 deaths, with strong evidence of

WHO’s core outbreak control strategies, when implemented promptly, have enabled many nations to limit NiV

attributed to rigorous contact tracing and decisive public health action.

6. Luby, S. P., Gurley, E. S., & Hossain, M. J. (2012). TRANSMISSION OF HUMAN INFECTION

7. Madhukalya, R., Yadav, U., Parray, H. A., Raj, N., Lupitha, S. S., Kumar, V., Saroj, A., Agarwal, V.,