Transmission dynamics of Nipah virus in Bangladesh and India, 2001-2026: systematic review and inference on reproduction number, offspring dispersion, and serial interval
- 1London School of Hygiene & Tropical Medicine
Abstract
BackgroundNipah virus (NiV) is a priority zoonotic pathogen causing high-fatality outbreaks. Early NiV outbreaks in Malaysia and Singapore had limited transmission beyond spillover events. However, since 2001, NiV outbreaks with person-to-person transmission have occurred in Bangladesh and India, driven by the NiV-Bangladesh genotype and NiV-India genotype. Our study aims to estimate the reproduction number, offspring dispersion, and serial interval governing NiV transmission in Bangladesh and India during 2001-2026.
MethodsWe conducted a systematic review of NiV outbreak investigations in Bangladesh and India, searching PubMed, Embase, Web of Science, and grey literature through 28 February 2026. Case-level offspring counts from 27 sources (323 cases across 67 outbreaks) were used as input to a hierarchical Bayesian negative binomial offspring distribution model. The serial interval was estimated by parametric distribution fitting to 137 transmission pairs. We conducted country-specific analysis and performed sensitivity analyses to evaluate the robustness of estimates.
ResultsPooling across 67 outbreaks, we estimated a median reproduction number of 0.43 (95% CrI: 0.26-0.75), an offspring dispersion parameter of 0.04 (0.03-0.06), and a serial interval of 13.3 days (95% CI: 12.8-13.8). Country-specific median reproduction numbers were 0.47 (0.22-0.98) for India and 0.35 (0.19-0.63) for Bangladesh, and dispersion parameters were 0.03 (0.02-0.06) and 0.05 (0.03-0.09), respectively, indicating marked overdispersion in both settings.
ConclusionNiV transmission is self-limiting on average and highly overdispersed, suggesting that a disproportionate share of onward transmission arises from a small number of cases. This epidemiological profile supports targeted containment measures, including contact tracing and quarantine, for effective NiV outbreak control.
Author SummaryNipah virus is a lethal infection that spreads from bats to people and, in some cases, from one person to another. Despite its severity as a high-consequence pathogen, there is no licensed vaccine or specific treatment. Since 2001, outbreaks have occurred almost every year in Bangladesh and India, which are the only places with person-to-person transmission. We gathered case reports from these outbreaks over twenty-five years and used a statistical model to measure how the virus spread between people. We found that, on average, each infected person passes the virus to fewer than one other person, so outbreaks tend to die out on their own without repeated introductions from animals. However, spread is heterogeneous: most people infect no one, while a small number infect many, occasionally producing large clusters. We estimated the typical time between one person falling ill and the next (serial interval) to be thirteen days. Together, these findings provide a better understanding of Nipah virus transmission and updated numbers needed to plan future prevention and control strategies for Nipah outbreaks.
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BibTeX
@misc{kim2026transmission,
title = {{Transmission dynamics of Nipah virus in Bangladesh and India, 2001-2026: systematic review and inference on reproduction number, offspring dispersion, and serial interval}},
author = {S. Kim and V. V. Mogasale and J. F. Vesga and H. Kang and L. Skrip and S.-m. Jung and A. Islam and A. Endo and W. J. Edmunds and K. Abbas},
howpublished = {medRxiv},
year = {2026},
month = jul,
doi = {10.64898/2026.07.16.26357631},
url = {https://www.medrxiv.org/content/10.64898/2026.07.16.26357631v2},
note = {CC BY},
}
RIS
TY - UNPB
TI - Transmission dynamics of Nipah virus in Bangladesh and India, 2001-2026: systematic review and inference on reproduction number, offspring dispersion, and serial interval
AU - S. Kim
AU - V. V. Mogasale
AU - J. F. Vesga
AU - H. Kang
AU - L. Skrip
AU - S.-m. Jung
AU - A. Islam
AU - A. Endo
AU - W. J. Edmunds
AU - K. Abbas
PY - 2026
DA - 2026/07/16
PB - medRxiv
DO - 10.64898/2026.07.16.26357631
UR - https://www.medrxiv.org/content/10.64898/2026.07.16.26357631v2
AB - BackgroundNipah virus (NiV) is a priority zoonotic pathogen causing high-fatality outbreaks. Early NiV outbreaks in Malaysia and Singapore had limited transmission beyond spillover events. However, since 2001, NiV outbreaks with person-to-person transmission have occurred in Bangladesh and India, driven by the NiV-Bangladesh genotype and NiV-India genotype. Our study aims to estimate the reproduction number, offspring dispersion, and serial interval governing NiV transmission in Bangladesh and India during 2001-2026. MethodsWe conducted a systematic review of NiV outbreak investigations in Bangladesh and India, searching PubMed, Embase, Web of Science, and grey literature through 28 February 2026. Case-level offspring counts from 27 sources (323 cases across 67 outbreaks) were used as input to a hierarchical Bayesian negative binomial offspring distribution model. The serial interval was estimated by parametric distribution fitting to 137 transmission pairs. We conducted country-specific analysis and performed sensitivity analyses to evaluate the robustness of estimates. ResultsPooling across 67 outbreaks, we estimated a median reproduction number of 0.43 (95% CrI: 0.26-0.75), an offspring dispersion parameter of 0.04 (0.03-0.06), and a serial interval of 13.3 days (95% CI: 12.8-13.8). Country-specific median reproduction numbers were 0.47 (0.22-0.98) for India and 0.35 (0.19-0.63) for Bangladesh, and dispersion parameters were 0.03 (0.02-0.06) and 0.05 (0.03-0.09), respectively, indicating marked overdispersion in both settings. ConclusionNiV transmission is self-limiting on average and highly overdispersed, suggesting that a disproportionate share of onward transmission arises from a small number of cases. This epidemiological profile supports targeted containment measures, including contact tracing and quarantine, for effective NiV outbreak control. Author SummaryNipah virus is a lethal infection that spreads from bats to people and, in some cases, from one person to another. Despite its severity as a high-consequence pathogen, there is no licensed vaccine or specific treatment. Since 2001, outbreaks have occurred almost every year in Bangladesh and India, which are the only places with person-to-person transmission. We gathered case reports from these outbreaks over twenty-five years and used a statistical model to measure how the virus spread between people. We found that, on average, each infected person passes the virus to fewer than one other person, so outbreaks tend to die out on their own without repeated introductions from animals. However, spread is heterogeneous: most people infect no one, while a small number infect many, occasionally producing large clusters. We estimated the typical time between one person falling ill and the next (serial interval) to be thirteen days. Together, these findings provide a better understanding of Nipah virus transmission and updated numbers needed to plan future prevention and control strategies for Nipah outbreaks.
ER -