Hantavirus cruise outbreak: 5 critical facts you need to know
2. The cruise ship’s confined environment created conditions for prolonged close contact, increasing vulnerability
One major reason health experts have urged calm despite the alarming deaths is that the Andes virus usually requires prolonged close contact with a symptomatic person for transmission between humans. Experts say the virus doesn't spread easily through brief encounters such as passing someone in public, ordinary conversation or short contact in open spaces.
Researchers are still studying the exact mechanisms involved in human transmission. Some evidence from earlier outbreaks in Argentina suggested droplets or aerosols may have played a role in certain crowded indoor settings. WHO officials nevertheless stressed that transmission appears far less efficient than airborne viruses such as SARS-CoV-2, the virus responsible for COVID-19. Scientists also believe people are most infectious when they are visibly ill, which helps public health authorities identify high-risk contacts more effectively.
The Andes virus also has a relatively long incubation period, estimated at up to six weeks in some cases. That means infected travelers may leave one country and develop symptoms much later somewhere else, complicating international monitoring and contact-tracing efforts.
The MV Hondius created conditions unusually favorable for this type of transmission. The expedition vessel carried fewer than 150 people from more than 20 countries in a confined environment for weeks at sea, The Wall Street Journal reports.
Some passengers shared small multi-person cabins with bunk beds, while daily life involved buffet meals, wildlife excursions, lectures, exercise sessions and long hours spent together indoors during rough South Atlantic weather. Several passengers also interacted closely while comforting those who became ill or grieving family members after the first death on board.
WHO technical lead Anaïs Legand said during a briefing, as reported by MIT Technology Review, that the multinational nature of the outbreak aboard a cruise vessel was something health authorities had not encountered before. Even so, WHO officials and outside experts believe the outbreak is unlikely to trigger widespread community transmission because the virus spreads poorly compared with highly contagious respiratory pathogens.
