The Centers for Disease Control and Prevention in the U.S. have reported an outbreak of Hantavirus Pulmonary Syndrome (HPS) in a campsite in Yosemite National Park, California. Six cases have been confirmed as HPS since 10 June, of which two have died. Four cases stayed in the ‘Signature Tent Cabins’ (permanently standing tents available for hire) in the Boystown area of Curry Village in Yosemite National Park; one in the area but not the tents and one case is still under investigation. The tents were disinfected and visitors moved on 24 August.
ECDC has conducted a rapid risk assessment to assess the risk for European visitors to Yosemite National Park, and the campsite in question, and for the general public in Europe.
ECDC has concluded that the risk of infection is low as only six cases have been confirmed so far while several thousands have visited Boystown area. As HPS is not transmitted from person to person there is no risk to the wider public in Europe from this outbreak. There is no need for public health measures to be taken for contacts of cases.
Clinicians are reminded to consider the diagnosis of HPS in all persons presenting with clinically compatible illnesses and to ask about potential rodent exposure or if they had recently visited Yosemite National Park.
During the outbreak period, 591 EU citizens made bookings for these tent cabins. In total, 1 923 people in booked groups from the EU stayed at the cabins (10 June– 24 August 2012) and were therefore potentially exposed to hantaviruses. The majority of them have been contacted already by the Park and the respective European national authorities are currently informing the remainder of the potential exposure and appropriate actions to be taken should they become ill.
The incubation period for HPS can be up to six weeks so it is possible that further cases will be identified in the coming weeks. Since its recognition in 1993, 602 cases have been reported in the US, of which 50 in the state of California, not including these recent cases. HPS exposures have previously only been found in Yosemite National Park in 2000 and 2010.
Rapid risk assessment: Hantavirus Pulmonary Syndrome outbreak in Yosemite Park, California, USA
ECDC Hantavirus health topic pages
Yosemite National Park – hantavirus updates
California Department of Public Health HPS health information
CDC hantavirus surveillance data