Two people have died and a further 12,000 people could be infected by a virus believed to have begun in California's Yosemite national park.
The hantavirus could have been spread through mouse faeces, saliva and urine, as the animals nested in rentable tents used by campers.
The tent-owning company have contacted over 3,000 people who used the tents in the Curry Village area of the park in June and July, while a further 9,000 could also be affected when they used the tents earlier in the year.
California's public health department have so far admitted that six people have contracted the hantavirus pulmonary syndrome at Yosemite, while further possible cases are being investigated.
According to the Guardian, 36% of people who contract the incurable virus die from the disease, which begins with flu-like symptoms before progressing to organ failure and respiratory problems.