Abstract
Background
Nipah 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.
Methods
We 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.
Results
Pooling 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.
Conclusion
NiV 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.
Source: Plos Neglected Tropical Diseases, https://doi.org/10.1371/journal.pntd.0014876
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