You only have so much space': the limits of reducing infection risk on cruise ships

"It was a voyage that promised such stuff as dreams are made of, yet within weeks the Atlantic expedition of the MV Hondius had become a nightmare, with three passengers dead from hantavirus and more showing symptoms. Meanwhile, an outbreak of norovirus is under investigation on another cruise ship, while flu, E coli and varicella the virus that causes chickenpox have also caused problems in such settings. Perhaps most memorably, in 2020 the Diamond Princess became a breeding ground for Covid, with passengers and crew quarantined for two weeks off the coast of Japan and more than 700 of the 3,711 people onboard eventually testing positive."

"In some ways, it is hardly a surprise that cruise ships can become hotbeds of infection: many are floating behemoths where those onboard interact frequently and at close quarters. Researchers also note that many of those onboard will have come from different countries, have travelled to different locations and have different degrees of immunity to diseases. What's more, the ship moves. Which means you have people potentially in contact with pathogens that they don't encounter on the day to day, says Dr Charlotte Hammer, an infectious diseases epidemiologist at the University of Cambridge."

"David Heymann, a professor of infectious disease epidemiology at the London School of Hygiene & Tropical Medicine, says: Whether or not [outbreaks] begin on a ship depends on who comes onboard, if any people are infected when they come onboard, and with which pathogen they might be infected. As Heymann points out, infections can be transmitted in different ways. One is through respiratory transmission between people, either via aerosols tiny particles that linger in the air and can be inhaled or via droplets that can either fall on people directly or contaminate sur"

An Atlantic cruise on the MV Hondius became a nightmare within weeks after hantavirus caused three passenger deaths and additional symptomatic cases. Other cruise outbreaks under investigation include norovirus, alongside problems from flu, E coli, and varicella. In 2020, the Diamond Princess became a major Covid outbreak, with passengers and crew quarantined off Japan and more than 700 of 3,711 testing positive. Cruise ships can act as infection hotbeds because onboard interactions are frequent and close, travelers come from many countries with different immunity levels, and the ship’s movement can expose people to pathogens encountered elsewhere. Older passengers may be more susceptible, increasing outbreak risk. Whether outbreaks begin depends on who boards, whether infected people are present, and which pathogens they carry, with transmission occurring through multiple routes.

Read at www.theguardian.com