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Investigation of an outbreak of "Humidifier Fever" in a print shop.

Mamolen M; Lewis DM; Blanchet MA; Satink FJ; Vogt RL
Am J Ind Med 1993 Mar; 23(3):483-490
An outbreak of acute illness in a print shop in Vermont was investigated. The outbreak affected a majority of the workers in a shop that had no previous reports of problems such as these. The owner of the shop requested a study be made as several of his workers had become ill the previous day. Of the 31 employees at work on the day of the outbreak, 28 were interviewed and blood samples were collected from 26 workers, 5 days after the onset of the illness. Sixteen of the 28 workers had symptoms of the disease with generalized muscle aches and fever or chills being the most common. The onset of symptoms ranged from 5 to 13 hours after entering the workplace, with a median onset being 7 hours. The illness lasted 2 to 24 hours. The workers ranged in age from 20 to 54 years. Workers over the median age of 26.5 years and women showed a tendency toward an increased risk of illness. A humidifier had been operating for the first time in many months on the day of the outbreak. An examination of the humidifier revealed that the baffles were covered with brownish grey sludge as it had not been cleaned since it had been purchased 19 months earlier. The ventilation system had not been functioning on the day of the outbreak. The intake filter was plugged, causing the system to shut down. Organisms isolated from the humidifier sludge included three species of the fungus Fusarium, ameba of the genus Acanthamoeba, and Gram negative bacteria. The authors recommend that the humidifier be cleaned on a daily basis and that the ventilation system be checked daily.
NIOSH-Author; Air-quality-control; Organic-dusts; Risk-factors; Microorganisms; Printing-industry; Aerosols; Ventilation-equipment; Indoor-air-pollution; Indoor-environmental-quality
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Journal Article
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American Journal of Industrial Medicine
Page last reviewed: May 11, 2023
Content source: National Institute for Occupational Safety and Health Education and Information Division