A suspected hantavirus outbreak aboard an international cruise ship traveling between Argentina and Cape Verde has resulted in three fatalities, triggering global public health scrutiny over how the typically rodent-borne pathogen spreads in enclosed passenger settings. The World Health Organization (WHO) has formally confirmed one case of the potentially lethal virus so far, while moving quickly to reassure global populations that the overall public risk remains low. Even with this official assessment, the unusual cluster of illnesses on the vessel has reignited longstanding questions about whether hantaviruses can spread from person to person in closed environments. Virginie Sauvage, who leads France’s National Reference Centre for Hantaviruses, told Agence France-Presse (AFP) that genetic sequencing of the virus strain involved will be the critical next step to unpack what occurred during the voyage.