Tuberculosis (TB) is the leading cause of death from a single infectious agent worldwide. The highest burden is found in Africa and Asia – mostly linked to the human immunodeficiency virus (HIV) epidemic in these regions. The 2020 World Health Organization (WHO) TB report showed that globally in 2019, 10 million people developed this disease.
Due to residual lung damage caused by pulmonary tuberculosis (PTB) patients are at increased risk from other chronic respiratory diseases, with one of the most common infections being chronic pulmonary aspergillosis (CPA) and aspergilloma.
TB and CPA can sometimes appear as clinically indistinguishable. CPA is often misdiagnosed as smear-negative PTB. With the high burden of PTB in developing countries, mostly being secondary to HIV, the incidence of CPA is probably higher but the index of clinical suspicion for CPA is very low. This may be partly contributed by the local shortage of mycological diagnostic capabilities. CPA destroys lung parenchyma with progressive cavitation, pleural thickening, and fibrosis. The usual lack of specific symptoms and a definitive diagnostic test leads to high mortality rates, even higher with antifungal drug resistance.
Around 373,000 people per year are thought to develop CPA as a complication of TB. There is a worldwide push to highlight the risk factors in TB patients that leave them open to developing further infections.
Here we look at some emerging case studies from India Uganda and Vietnam.
A study carried out by R. Singla and colleagues in New Delhi showed that 57% of post-TB patients have evidence of CPA. This figure is higher than originally thought and greater than in comparative studies in Uganda. Patients are on average, male, mean age of 41 and from low socio-economic backgrounds.
The Ugandan study by Richard Kwizera and colleagues in Kampala highlighted that almost 35% of subjects with CPA might be wrongly treated with anti-TB medication despite the lack of microbiological evidence. This is also very common in resource-limited settings where the index of clinical suspicion for fungal infections is very low.
Vietnam study from Ngoc Thi Bich Nguyen in Hanoi demonstrated that 54.3% of post-TB treatment patients had CPA. The male/female ratio was 3/1 (28 males and 10 females). CPA patients had an average age of 59. Patients had often been receiving treatment for TB for over 10 years before presenting with CPA. The most common identifier in these cases was pleural thickening.
These studies all recommend that every patient with TB, active or with a prior history, should be screened for CPA to prevent the possibility of having a co-infection, especially if symptoms persist despite anti-tuberculous therapy. CPA has to be an active consideration when dealing with other respiratory diseases with similar non-specific symptoms. CPA is being underestimated and often confused with another chronic pulmonary disease, especially smear-negative TB. The years of misdiagnosis of tuberculosis and incorrect treatment is addressable with clinical training and testing for fungal disease and aspergillosis.