Coccidioidomycosis among Workers at an Archeological Site, Northeastern Utah

In 2001, an outbreak of acute respiratory disease occurred among persons working at a Native American archeological site at Dinosaur National Monument in northeastern Utah.Epidemiologic and environmental investigations were undertaken to determine the cause of the outbreak.A clinical case was defined by the presence of at least two of the following symptoms: self-reported fever, shortness of breath, or cough.Ten workers met the clinical case definition; 9 had serologic confirmation of coccidioidomycosis, and 8 were hospitalized.All 10 were present during sifting of dirt through screens on June 19; symptoms began 9-12 days later (median 10).Coccidioidomycosis also developed in a worker at the site in September 2001.A serosurvey among 40 other Dinosaur National Monument workers did not find serologic evidence of recent infection.This outbreak documents a new endemic focus of coccidioidomycosis, which extends northward its known geographic distribution in Utah by approximately 200 miles.C occidioidomycosis results from inhaling spores (arthroconidia) of Coccidioides immitis, a soildwelling fungus endemic to the southwestern United States and parts of Mexico, Central America, and South America.The organism is recovered from soil in areas with yearly annual rainfall averaging 5-20 inches, hot summers, infrequent winter freezes, and alkaline soil (1).Although up to 100,000 new infections may occur annually (2), reported point source outbreaks are infrequent and have followed diverse soil-disrupting activities or events, such as archeological or anthropological digs (3-5), military maneuvers (6), play involving throwing dirt (7), construction work (8), earthquakes (9), dust storms (10,11), model airplane flying competitions (12), and armadillo hunting (13).We report a point-source outbreak of coccidioidomycosis among workers who participated in soil-disrupting activities at an archeological site in Dinosaur National Monument in northeastern Utah during June and July 2001.This site was approximately 200 miles north of previously known C. immitis-endemic areas for in Utah (Figure 1).In addition, we report results of a serologic survey of Dinosaur National Monument employees performed to assess recent exposure to C. immitis. Outbreak SettingDinosaur National Monument covers 320 square miles in the Uinta Basin in northeastern Utah and northwestern Colorado (Figure 1).A total of 397,800 visitors were recorded in 2000.During summer 2001, 49 permanent and 49 seasonal employees, as well as approximately 120 volunteers, worked at the monument.