As humans encroach(侵害する)more and more on their native territory, Australian koalas have fewer eucalyptus trees to inhabit. The stress of their increasingly difficult living situation is bringing out a latent(潜在的な)disease that is infecting 50 to 90 percent of the population. Chlamydiosis is a virus that spreads among koalas in times of stress, leading to infections in the eyes and urinary, reproductive, and respiratory tracts. This is causing koala numbers to decline at an alarmingly fast rate. The problem earned widespread attention after Sam the Koala, famed for being photographed drinking from a fireman’s water bottle in the midst of a wildfire, died during surgery to treat the disease.