Radiographic changes in humidifier fever

Bird Fancier's Disease Due to Exposure to Birds Via a Desert Cooler

Hypersensitivity pneumonitis (HP) is an immunologically mediated pulmonary disease caused by various organic particles and some non-organic chemicals. HP is mostly associated with some occupations such as farming and bird breeding. We report a case of hypersensitivity pneumonitis in a housewife without any prior history of occupational exposures. The disease was developed due to indirect exposure of the patient to doves antigens via a desert cooler ducts.

Sump bay fever: inhalational fever associated with a biologically contaminated water aerosol

OBJECTIVE

To investigate the clinical, serological, and environmental features of a work related inhalational fever associated with exposure to an aerosol generated from a biologically contaminated 130,000 gallon water pool in a building used for testing scientific equipment.

METHOD

Cross sectional survey of all exposed subjects (n = 83) by symptom questionnaire, clinical examination, spirometry, and serology for antibody to Pseudomonads, pool water extract, and endotoxin. In symptomatic patients diffusion capacity was measured, and chest radiology was performed if this was abnormal. Serial peak flow was recorded in those subjects with wheeze. Bacterial and fungal air sampling was performed before and during operation of the water pool pump mechanism. Endotoxin was measured in the trapped waters and in the pumps. Serum cotinine was measured as an objective indicator of smoking.

RESULTS

Of the 20 symptomatic subjects, fever was most common in those with the highest exposure (chi 2 42.7, P < 0.001) in the sump bay when the water was (torrentially) recirculated by the water pumps. Symptoms occurred late in the working day only on days when the water pumps were used, and were independent of the serum cotinine. Pulmonary function was normal in most subjects (spirometry was normal in 79/83, diffusion capacity was low in five subjects, chest radiology was normal). Peak flow recording did not suggest a work relation. The bacterial content of the aerosol rose from 6 to > 10,000 colony forming units per cubic metre (cfu/m3) (predominantly environmental Pseudomonads) when the pumps were operating. High endotoxin concentrations were measured in the waters and oil sumps in the pumps. Low concentrations of antibody to the organisms isolated were detected (apart from two subjects with high antibody) but there was no relation to exposure or the presence of symptoms and similar antibody was found in the serum samples from a non-exposed population. The fever symptoms settled completely with the simple expedient of changing the water and cleaning the pumps.

CONCLUSION

Given the results of our study, the development of inhalational fever in this unique environment and clearly restricted cohort was closely related to the degree of exposure to contaminated aerosol and mainly occurred in the absence of distinct serological abnormality and independent of cigarette smoking.

Hypersensitivity pneumonitis associated with home ultrasonic humidifiers

We describe five patients with hypersensitivity pneumonitis (HP) that was related to using home ultrasonic humidifiers. All patients had micronodular infiltrates on their chest radiograph, and their lung biopsy specimens revealed alveolitis with or without epithelioid cell granulomas. Challenge tests were performed on two patients with the humidifier water and three patients using the humidifier. All patients tested exhibited a positive response. Tests for precipitating antibodies against an extract of the humidifier water gave strongly positive reactions in all patients tested. Precipitins to Cephalosporium acremonium and Candida albicans were also present in all cases, whereas precipitins to thermophilic actinomycetes were not detected. Although cultures of the water grew a variety of fungal and bacterial organisms, thermophilic actinomycetes could not be detected. These findings suggest that thermophilic organisms may not be the causative antigens of HP associated with ultrasonic humidifiers. All five patients had an increase in the bronchoalveolar lavage (BAL) lymphocytes that were predominantly CD4+ lymphocytes. The T helper cell count (CD4) to suppressor T cell count (CD8) ratio was significantly higher than that observed in summer-type HP, and lower than that observed in bird fancier's lung, indicating that the phenotypes of the BAL lymphocytes may vary with the type of HP.

Discriminant analysis of symptom pattern and serum antibody titres in humidifier related disease

BACKGROUND

The heterogeneous patterns of symptoms among factory workers exposed to aerosols from contaminated air humidifiers were analysed to assess the association between specific symptoms and the serum IgG antibody response to the humidifier water contaminants, and to test the ability of specific symptoms to predict this antibody response.

METHODS

Symptoms from 88 factory workers were surveyed by a doctor administered questionnaire and compared with their serum IgG antibody titres to humidifier water contaminants quantified by enzyme immunoassay.

RESULTS

The strength of association between individual symptoms and antibody showed that fever, shivering or chills, influenza-like symptoms, or headache were individually significantly associated with the presence and higher titres of antibody. This was also true for those subjects whose symptoms were most pronounced during the first day of the working week. Within each subject's full symptom profile there were significant associations between the description of chest tightness, breathlessness, and wheeze; between headache and influenza like symptoms; between fever and shivering or chills; and between intermittent onset and general tiredness. Discriminant analysis of the full symptom profiles showed that there was maximum information content in five independent parameters, namely, the descriptions of fever, headache, and chest tightness, the timing of their onset, and the readiness to describe miscellaneous symptoms in addition to those in the questionnaire. On the basis of these criteria 72% of subjects could be classified according to their antibody state. Cluster analysis with these five independent parameters described four symptom clusters: one associated with high median antibody levels, one with low, and two with zero median levels. These were, respectively: (1) fever with headache and chest tightness; (2) either no or few symptoms; (3) chest tightness and headache with intermittent onset; (4) headache and miscellaneous symptoms with intermittent onset.

CONCLUSIONS

The association between serum antibody titres and specific symptom patterns may identify different categories of disease which constitute the spectrum known as humidifier related disease, and strengthens the hypothesis that antibody may be involved in the pathogenesis of some components of the disease.

Quantifying serum antibody class and subclass responses by enzyme immunoassay in humidifier-related disease

Antibody activity in the major classes and IgG subclasses against antigens in factory humidifier water was quantified by enzyme immunoassay (EIA) in 88 subjects who were exposed at work to the output from these contaminated humidifiers. Those with work-related symptoms had significantly higher mean titres than those who were symptom free, although values overlapped. The individuals with the highest IgG antibody titres also had the highest titres of IgM and IgA antibody, and these parameters did not discriminate between those with and without symptoms any better than the IgG titre. This was also true for the IgG subclasses where activity was predominantly measured in IgG1. Quantifying the IgG antibody allowed us to demonstrate a significant correlation with years of work exposure (P less than 0.001). There was no significant association between antibody and cigarette smoking, as assessed by smoking history and confirmed objectively by serum cotinine levels. There was a significant correlation with total IgG level (P less than 0.001) suggesting that a non-specific immune enhancement may accompany the specific response. The antibody titres were followed up to 3 years after modification of the humidification systems, and during this time symptoms resolved and the antibody levels progressively fell to undetectable levels. The EIA was adapted to measure antigen at nanogram levels thus providing a rapid test for screening of humidifer water as well as a technique that may help identify the nature of the antigens involved.

Osmotic challenges in the assessment of bronchial hyperresponsiveness

It is now well recognized that a change in osmolarity of the periciliary fluid is a potent stimulus to airway narrowing and may be a common cause for provoking an attack of asthma. This has led to the use of nonisotonic aerosols to document bronchial hyperresponsiveness in patients with clinical asthma. These aerosols are generated by ultrasonic nebulizers, and the most commonly used are water, hyperosmolar sodium or potassium chloride, and dextrose. An increase in specific airway resistance of 100% or a reduction in FEV1 of 20% is considered as an abnormal response to these aerosols. There are a number of factors that affect the airway response to these aerosols, and these include the osmolarity of the solution and its ionic content and pH. In addition responses may be affected by a previous challenge or medication. It is not known precisely how these aerosols act to induce airway narrowing, but it is not by a direct action on smooth muscle. It is thought that a change in osmolarity of the airways causes the release of inflammatory mediators, which then act to narrow the airways. For this reason challenge by nonisotonic aerosols is different from challenge by histamine and methacholine and may be preferable for the diagnosis of asthma and assessment of its treatment.

Serological and clinical investigation of humidifier fever

A group of nineteen normally healthy subjects in a microprocessor factory reported various degrees of work-related respiratory and systemic symptoms that in some were suggestive of humidifier fever (HF). They all had normal serology against a variety of infectious agents, but serum-precipitating antibody against antigens in the factory humidifier water was present in twelve subjects, primarily those with symptoms most in keeping with HF. There was extensive serological identity between the antigens from this and other confirmed sources of HF. The antibody-positive subjects were all non-smokers and had significantly raised serum IgG. Nine months later, following modification of the humidifier system, the symptoms had resolved in fourteen of the nineteen subjects, the precipitins were reduced in seven but persisted in five subjects, and the total IgG levels were significantly reduced in all subjects. The measurement of total, as well as specific, IgG may be of value in assessing this disease.

Extrinsic allergic alveolitis caused by a cold water humidifier

Three workers developed classical extrinsic allergic alveolitis while working in a printing works that had a contaminated cold water humidifier. All had nodular shadows on their chest radiographs, reduced gas transfer measurements, and lung biopsy specimens that showed an alveolitis with giant cells and cholesterol clefts. In two subjects bronchoalveolar lavage was performed and the lavage fluid contained more than 70% lymphocytes in each case. Bronchial provocation tests with the humidifier antigen in these two workers reproduced their symptoms. Unlike previously reported cases, where exposure was to humidifiers working at generally higher temperatures, challenge with thermophilic actinomycetes in our two patients produced no reaction. Tests for precipitins to the humidifier antigen gave strongly positive reactions in the three workers but no single organism isolated from the humidifier produced a significantly positive reaction.