Is it TB or a fungal lung infection? New life saving guidelines released today
August 08 2018
Currently 45% of TB diagnosis is only clinical and not confirmed with tests. Up to 20% of these diagnoses are incorrect. A common missed diagnosis is fungal lung infection. The most common of these is chronic pulmonary aspergillosis or CPA. The treatment of TB and CPA treatment is completely different and untreated CPA has an 80% 5 year mortality.
An example of severe CPA in the upper left lung (arrow) with fluid in the cavity.
To address this, the Global Action Fund for Fungal infections, GAFFI, convened an expert international panel to develop a workable definition of CPA for resource-constrained countries. In the studies on CPA done to date several different combinations of criteria have been used to define the disease. In most of these studies a CT scan of the chest is necessary, but this facility is not routinely available for the majority of the world’s population.
The panel debated several iterations and combinations of defining characteristics for CPA which are published online today in the prestigious Emerging Infectious Diseases journal. These are the final conclusion – 1, 2 and 3 required:
1 - Symptoms for 3 months or longer (haemoptysis and/or persistent cough, and/or weight loss) (other symptoms are common, but not required, notably fatigue, chest pain, breathlessness and sputum production)
2 - Radiological features (progressive cavitation on chest imaging AND/OR intracavitary fungal ball AND/OR pleural thickening or pericavitary fibrosis or infiltrates all adjacent to cavities)
3 - Microbiological evidence of Aspergillus infection (positive Aspergillus-specific IgG and/or sputum microscopy showing hyphae consistent with Aspergillus and/or Aspergillus growth on 2 or more sputum or other respiratory samples)
In addition the panel noted that TB and non-tuberculous mycobacterial infection should be ruled out with smear, GeneXpert and/or mycobacterial culture. It is possible for mycobacterial infection and CPA to be present concurrently, and further testing is required.
Professor David Denning who lead the workshop (University of Manchester and Chief Executive of GAFFI) stated: “Basing a diagnosis of TB solely on a chest radiograph, without laboratory confirmation, leads to many errors. CPA and other fungal lung infections are slower in evolution than TB, but too often lead to years of ill health and then death if not diagnosed. Recognising that some tests (fungal cultures and CT scanning) are not available in many resource-constrained countries, we have developed a diagnostic algorithm and set of diagnostic criteria to reduce the number of incorrect ‘TB’ diagnoses.”