A recent survey of over forty patients fom Liverpool showed only one to be a life long non-smoker. Patients may present with acute or chronic illness that is and radiographically clinically indistinguishable from tuberculosis. Symptoms are usually chronic and include cough with sputum and sometimes haemoptysis, weight loss, malaise and night sweats. Symptoms may be insidious and occur over many months before the patient presents. A recent study looking at the symptomatic presentation of M. kansasii infection compared with tuberculosis, found that with exception of diabetes and alcohol intake, which favoured a diagnosis of tuberculosis, there were no features between the two, likely to be diagnostically helpful.
Some patients have disease presenting insidiously over more than a year.
Weight loss and cachexia are often accompanied by long standing respiratory symptoms. These are often attributed to the pre-existing pulmonary disease. Mycobacterial infection may be missed if it is not considered and the appropriate investigations requested. The chest radiograph may be difficult to interpret, often showing chronic abnormalites which may be attributed to the preexisting lung disease. Genuine infection likely if several specimens show the same strain of mycobacteria from symptomatic patients whose chest x-ray shows abnormalities consistant with mycobacterial disease.