Acute presentation: flu-like illness with cough;
Subacute: recurrent "pneumonia";
Chronic: exertional dyspnea, productive cough, and weight loss;
The exposure is to microbially contaminated, water-based metalworking fluids (MWFs) used by machinists, and the antigens are mainly Mycobacteria immunogenum; [Occupational Exposure to Metalworking Fluids, NIOSH, Publication No. 98-102; ATS/IDSA Statement: Nontuberculous Mycobacterial Diseases) Forty-four cases of MWF HP occurring in ten different plants have been confirmed by lung biopsy. Concentrations of MWF aerosols in these plants were in most cases below the current OSHA standard. Recent studies have implicated Mycobacteria immunogenum, closely related to M. chelonae, as the causal agent. Improved engineering controls are needed to reduce exposure to MWFs. [Rosenstock, p. 1043-54] The main species involved is M. immunogenum (identified previously as M chelonae or M. abscessus; [PMID 18821262
] See Table 1: "Diagnostic criteria for hypersensitivity pneumonitis." [Trout D, et al. Evaluation of Hypersensitivity Pneumonitis Among Workers Exposed to Metal Removal Fluids. Appl Occup Environ Hyg 2003 Nov,18(11):953-60] Quantitative PCR can measure M. immunogenum load in MWF samples with greater sensitivity and shorter processing times than cultures. [PMID 18821262
] "Contamination of MWFs with mycobacteria is often underestimated because of laboratory methods that lack sensitivity to detect them." [PMID 23546507
] See "Hypersensitivity pneumonitis."