Koalas are susceptible to chlamydia. In 2012, a koala ward in Australia treated approximately 300 cases of chlamydia. Chlamydia in koalas is not the same strain found in humans.
Koala chlamydia can be transmitted through blood and sexual contact. As of 2013, there is a 90 percent infection rate in some parts of Australia. The disease can affect males, females and joeys. Symptoms of an infection include conjunctivitis and "dirty tail" caused by urinary tract infections and incontinence. Without treatment, chlamydia in koalas can lead to blindness, infertility and death. The infection can be treated with antibiotics if it is caught early. Treatment lasts a few months before healthy koalas are released.