Three people have died aboard the cruise ship MV Hondius, en route between Argentina and the islands of Cape Verde. The World Health Organization has confirmed one case of hantavirus, with five more under investigation. The virus does not spread person to person - it is transmitted through inhalation of particles from rodent excrement. On board a ship. Among passengers.

Hantavirus is a family of viruses whose main reservoir is rodents. Infection causes two serious diseases: hantavirus pulmonary syndrome (HPS) with a 38 percent mortality rate and a haemorrhagic fever with kidney failure. There is no specific therapy - treatment is supportive: oxygen, ventilator, dialysis, intensive care.

Hantavirus is not new: 150,000 cases are recorded worldwide every year, most in Europe and Asia (China alone accounts for more than half). The US has registered 890 cases since 1993. But outbreaks on the Atlantic Ocean, on a cruise ship full of passengers, is a very different context.

The people who paid for a cruise got something else entirely. And for now, three families are missing their loved ones.