ISLAMABAD   -  Scientists say Australia’s iconic koala bear is at risk of extinction due to stress on its immune systems caused by bushfires and habitat destruction. Aussie researchers have analyzed 29 years of data from three koala hotspots in New South Wales, the country’s eastern state. Koala populations have steadily declined mostly due to disease – the most common reason that they’re admitted into care in the three locations – with chlamydia being the most common condition, they found. But bushfires and destruction of their habitat by humans – to create new building developments, for example – have made koalas more susceptible to disease by stressing their immune systems. Stress from these events triggers the production of a class of hormones called glucocorticoids, they say. ‘Any disturbance toanimals habitat activates the physiological stress response, and if said stressors do not cease, the excessive production of glucocorticoids can leave the animal with a compromised immune system and therefore likely to contract a disease,’ say the experts from Western Sydney University and the University of Queensland.