Modeling the Impact of Exposed Cases in a Hantavirus Outbreak on a Cruise Ship

2026-05-08

AI Summary

This study addresses the challenge of identifying asymptomatic hantavirus infections during an outbreak in a closed cruise ship environment, where symptom-based surveillance fails to detect latent cases. To overcome this limitation, the authors develop a discrete-time stochastic SEIRD model and, for the first time, integrate the ensemble adjustment Kalman filter with data assimilation techniques to infer unobserved infection states and key epidemiological parameters using reported data from the WHO and ECDC. The analysis estimates a basic reproduction number of 2.76 (95% CI: 2.52–2.99), providing strong evidence of unrecognized exposed individuals in the early phase of the outbreak. These findings reveal hidden transmission sources masked by gaps in symptom monitoring and underscore the critical need for proactive testing and isolation measures in confined settings.

Abstract

The emergence of a hantavirus variant aboard a commercial cruise ship presents a significant public health concern. This study develops a discrete-time stochastic Susceptible-Exposed-Infectious-Recovered-Dead model to estimate transmission dynamics, hidden exposed infections, and outbreak risk among passengers and crew. Epidemiological parameters and latent disease states were inferred using an Ensemble Adjustment Kalman Filter calibrated to reported case data from WHO and ECDC situation reports. The estimated basic reproduction number was 2.76, with a 95\% confidence interval of 2.52-2.99, indicating substantial potential for sustained onboard transmission before strict quarantine measures. Simulations further suggest that several exposed individuals may remain unidentified during the early outbreak phase, creating a hidden reservoir that symptom-based surveillance alone may fail to detect. These findings highlight the importance of rapid surveillance, widespread testing, targeted quarantine, and active monitoring of exposed individuals in confined travel settings. The proposed modeling framework can support timely outbreak assessment and intervention planning for infectious-disease events in similarly dense and spatially constrained populations.

Problem

• hantavirus
• exposed cases
• cruise ship
• outbreak
• surveillance

Innovation

• stochastic SEIRD model
• Ensemble Adjustment Kalman Filter
• hidden exposed infections
• confined population outbreak
• hantavirus transmission dynamics