Chlamydia in koalas is caused by two kinds of bacteria, Chlamydia pecorum and C. pneumoniae, which are different from the bacteria that usually causes the disease in humans.

How did koalas get chlamydia?

Koalas in the wild are exposed to chlamydia through sexual contact, and newborns can contract the infection from their mothers.

Can a koala scratch give you chlamydia?

The more common strain, Chlamydia pecorum, is responsible for most of the outbreak in Queensland and cannot be transmitted to humans. The second strain, C. pneumoniae, can infect humans if, say, an infected koala were to urinate on someone, though it's unlikely.