The CDC urged lab testing of patients who exhibit symptoms consistent with the lung disease, hantavirus pulmonary syndrome, after a stay at the California park between June and August and recommended that doctors notify state health departments when it is found.
Two men have died from hantavirus linked to the Yosemite outbreak and four others were sickened but survived, while the CDC said additional suspected cases were being investigated from "multiple health jurisdictions."
Most of the victims were believed to have been infected while staying in one of 91 "Signature" tent-style cabins in Yosemite''s popular Curry Village camping area.
"An estimated 10,000 persons stayed in the ''Signature Tent Cabins'' from June 10 through August 24, 2012," the CDC said. "People who stayed in the tents between June 10 and August 24 may be at risk of developing HPS in the next six weeks."
Yosemite officials earlier this week shut down all 91 of the insulated tent cabins after finding deer mice, which carry the disease and can burrow through holes the size of pencil erasers, nesting between the double walls.
Park authorities said on Friday that they had contacted approximately 3,000 parties of visitors who stayed in the tent cabins since mid-June, advising them to seek immediate medical attention if they have symptoms of hantavirus.
Nearly 4 million people visit Yosemite, one of the nation''s most popular national parks, each year, attracted to the its dramatic scenery and hiking trails. Roughly 70 percent of those visitors congregate in Yosemite Valley, where Curry Village is located.
The virus starts out causing flu-like symptoms, including headache, fever, muscle ache, shortness of breath and cough, and can lead to severe breathing difficulties and death.
The incubation period for the virus is typically two to four weeks after exposure, the CDC said, with a range between a few days and six weeks. Just over a third of cases are fatal.