A rare hantavirus outbreak linked to the Expedition cruise ship, MV Hondius, has prompted an international health response after multiple passengers tested positive and three people died. 

Health officials suspect the outbreak involves the Andes strain of hantavirus, which is unusual because it may spread person-to-person. Passengers and crew from more than 20 countries were evacuated and quarantined as the ship arrived near Spain’s Canary Islands. 

United States’ officials confirmed that one American passenger tested positive, while another showed symptoms during evacuation flights. 

A flight attendant connected to the operation later tested negative, easing some fears of wider spread. The Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) will continue to monitor the situation closely as investigations focus on how the virus had spread aboard the ship.