Objective To investigate a humidifier fever event in a workshop, and provide evidence for dealing with such events in the future.
Methods Field epidemiological survey such as case investigation and field environment investigation combining laboratory test was conducted to collect data.
Results A total of 32 cases were reported in the event, with a morbidity rate of 50%. Two ultrasonic humidifiers were equipped in the workshop, and the use of humidifiers was closely related to the occurrence of humidifier fever. Drinking water, humidifier pipe water, and tank water samples were detected. Bacillus cereus and Pseudomonas aeruginosa were detected in the water samples from humidifier tanks. The total bacterial counts in the pipe water and tank water samples from the 2nd humidifier were 1 800 cfu/mL and 600 cfu/mL, respectively.
Conclusion The humidifier fever event is caused by the pathogenic microorganisms (mainly Bacillus cereus and Pseudomonas aeruginosa) in water from humidifier tanks and pipes.
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