Chronic pulmonary aspergillosis (CPA) -- a common fungal infection that claims 340,000 lives every year worldwide, can turn lethal for about 1 in three people with lung diseases, according to a study by researchers including from the All India Institute of Medical Sciences (AIIMS), Delhi.

CPA, caused by exposure to airborne spores of the mould Aspergillus, causes gradual scarring of the lungs for months and years. It is a debilitating condition that causes severe tiredness, weight loss, breathlessness, and coughing up blood. While exposure to Aspergillus is harmless to most people, it may affect those with lung damage.

The international study of CPA is  led by Professor David Denning from The University of Manchester and published in the leading journal Lancet Infectious Diseases showed that around 32 per cent of people who have had prior damage from lung diseases will die after five years if they also get infected by CPA.Nearly 15 per cent of people with CPA will die in the first year following other lung diseases.

Co-authors Dr Abinhav Sengupta and Dr Animesh Ray from Delhi-based AIIMS examined the death rates in 8,778 patients described in the literature from all continents except Antarctica.

The international study including researchers from the University of Manchester, showed that CPA patients with prior tuberculosis (TB) had a lower overall 5-year mortality of 25 per cent.

However, they also found that patients with CPA end up being misdiagnosed as having TB, and then not treated with antifungal agents.

Treatment with antifungal drugs or surgery is key to improving symptoms and also reducing the risk of death, the researchers said.

Though patients with TB tend to be younger, a multivariable analysis showed prior TB was 24% less lethal than other lung conditions, even accounting for age, though the reason for the difference in outcome was not identified.

Being older than 60, having interstitial lung disease, current cancer and smoking-related lung disease carried worse outcomes, said the team.

Caused by exposure to airborne spores of the mould Aspergillus, it is harmless to most people, but not to those with lung damage, maintained the  researchers.