90-Second Read: The Hantavirus Andes strain: can it be contained?

He also showed that Hantaviruses, which are carried by rodents, can be inhaled by humans in dust contaminated by droppings or urine. They divide into two groups: Old World Hantaviruses, in Europe and Asia, cause kidney dysfunction and have a mortality rate of 1% to 15%; New World ones, in the Americas, lead to severe lung infections and are fatal in around 40% of cases. The Andes strain does not spread easily: it requires intimate or very close contact. Since then, numerous strains that can be transmitted to humans have been identified.

Health officials have stressed that we are not facing a pandemic. And though many passengers left the ship weeks ago, there have so far been no "third-generation" cases, among people who were not on board. Given the virus's incubation period, clinicians say that 21 June is the date to watch: if there have been no third-generation cases by then, it means the outbreak has run its course. Get the facts behind the news, plus analysis from multiple perspectives.

Doctors suspected that a virus might be to blame, but it wasn't until 1978 that a Korean scientist isolated the culprit in a mouse, and named it after a nearby river, the Hantan. The troops had likely kicked the virus up as they dug foxholes. A Dutch ornithologist who fell ill on 6 April and died five days later has been identified as "patient zero". This week, 20 British nationals on board flew home to the UK, and were bussed to an isolation facility on the Wirral, said Sarah Knapton in The Daily Telegraph.