Humidifier-associated disease in the general population:: a retrospective investigation

Background and objective: Recently an increasing number of patients presented with febrile and respiratory symptoms associated with exposure to a new type of domestic ultrasonic humidifier. Patients and methods: We report on 14 patients (5 females, 9 males: average age 42.5 +/- 17.4 years) with recurrent episodes of fever, cough and dyspnea after repeated exposure to ultrasonic misting fountains at home. Results: A diagnosis of extrinsic allergic alveolitis (humidifier lung: 12 patients) or toxic alveolitis (humidifier fever: 2 patients) was made on the basis of the history and the clinical, radiological, laboratory and immunological findings. 10 patients had a partial respiratory insufficiency at rest or on exercise, 9 had a restrictive ventilatory abnormality. The chest x-ray was abnormal in 7 patients. Of 8 patients in whom computed tomography was done 6 had typical changes of an exogenous allergic alveolitis. Bronchoalveolar lavage revealed lymphocytic alveolitis in 8 patients. In 12 patients bacteria, moulds and/or yeasts were demonstrated in the humidier fluid which they had used. 13 patients had IgG antibodies to the humidier fluid. 8 patients were subjected to inhalative challenge tests to their own ultrasonic misting fountain: all of them had positive reactions. Conclusions: These cases demonstrate the potential of ultrasonic humidifying devices to cause illness in the home. In view of their increasing popularity, humidifier lung and humidifier fever should be considered in the differential diagnosis of patients with unexplained pulmonary or flu-like illness with fever.