Cruise Ship-Associated Andes Virus Cluster aboard MV Hondius, 2026: A Stochastic Scenario Analysis

Abstract

In April 2026, the MV Hondius expedition cruise ship became the site of the first documented cruise ship-associated Andes hantavirus (ANDV) cluster, with 13 confirmed and probable cases and 3 deaths among 149 passengers and crew. We applied a stochastic epidemic model to evaluate four embarkation scenarios under reproductive numbers anchored to published ANDV estimates. Scenario D, involving two latent infected persons at embarkation, was most consistent with the observed outbreak, yielding P(final size >= 13) = 11.6% and P(takeoff) = 58.5% at R0 = 2.12. Approximate Bayesian computation provided complementary support for multiple latent infections at embarkation, especially E1(0)=1 and E3(0)=2, but R0 remained weakly identifiable. A day-35 transmission reduction changed takeoff probability little in this counterfactual model. Findings support exposure-history assessment, early onboard surveillance, rapid isolation of symptomatic cases, and postdisembarkation monitoring for travelers from ANDV-endemic regions.