Yosemite National Park hantavirus outbreak: 10 confirmed cases, 3 deaths

Since the outbreak began in mid-August, there have been 10 cases and three deaths of Hantavirus Pulmonary Syndrome (HPS) linked to Yosemite National Park’s “signature” cabins in Curry Village, according to a CDC Morbidity and Mortality Weekly Report (MMWR) for release Nov. 23.

The 10 confirmed patients came from three states: California (eight), West Virginia (one), and Pennsylvania (one). Ages ranged from 12 years to 56 years; four were female. Nine patients had typical symptoms of HPS, and one lacked respiratory symptoms; three died.

Nine patients stayed in Curry Village “signature” cabins, which have insulation between the canvas exterior and interior hard walls. Rodent infestations were detected in the insulation, and all 91 signature cabins were closed indefinitely on August 28.

The CDC notified public health officials and clinical providers in the United States and internationally. The National Park Service notified by e-mail, telephone, or mail all registered overnight Yosemite National Park visitors (approximately 260,000 guests) who had stayed at the park during June 1–September 17, 2012.

According to the agency, HPS is a nationally notifiable disease caused in the United States most commonly by Sin Nombre virus. The deer mouse (Peromyscus maniculatus) is the reservoir. Infected mice shed virus in urine, feces, and saliva. Humans become infected through inhalation of aerosolized virus from rodent excreta and via direct contact from rodent bites.

The incubation period ranges from 1 to 6 weeks. Early symptoms include fever, chills, myalgia, headache, and gastrointestinal symptoms for 1–7 days, progressing rapidly to respiratory distress and shock . Most patients require hospitalization, supplemental oxygen, and intubation. The case-fatality rate is approximately 36%.

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