Hantaviruses are not new. They have circulated for decades in rodent populations, particularly in rats and mice. Humans can become infected if they are bitten or scratched by a rodent or by inhaling aerosolised particles. These are tiny bits of rodent urine, faeces or saliva floating through the air that are contaminated by the virus.
There are many different hantaviruses but only one can spread from person to person: the Andes hantavirus from South America. This is the strain that recently killed several cruise ship passengers.
Infections between humans can be prevented by closely observing people who were exposed and isolating those who are sick. This limits the risk of further spread, as transmission generally requires close contact.
