While Chlamydia in koalas is primarily spread as a sexually transmitted infection among adults, studies demonstrate that young joeys can acquire the bacteria directly from their mothers.
The claim states that koalas are born with or acquire chlamydia from their mothers. Multiple retrieved papers (specifically [0] and [7]) investigate young koalas/joeys and conclude that mother-to-young transmission of Chlamydia pecorum does occur alongside sexual transmission. There are no papers contradicting this finding, supporting a verdict of SUPPORTED.