Waddlia chondrophila: from a bovine abortigenic agent to a potential cause of human adverse pregnancy outcomes

<i>Waddlia chondrophila</i> is a strict intracellular bacterium belonging to the <i>Chlamydiales</i> order, which also encompasses important human and animal pathogens, including <i>Chlamydia trachomatis</i> and <i>Chlamydia psittaci</i>. Like all other members of the order, <i>W. chondrophila</i> displays a biphasic developmental cycle, alternating between infectious extracellular and replicative intracellular forms.First isolated from a bovine aborted foetus, <i>W. chondrophila</i> was later demonstrated to be associated, in women, with adverse pregnancy outcomes, such as miscarriage. Furthermore, recent studies have demonstrated a high prevalence of anti-<i>W. chondrophila</i> antibodies in asymptomatic women who consulted doctors regarding infertility problems, and in the male patients of infertile couples. Additionally, a role for this bacterium in respiratory tract infections has been suggested, as it has also been recovered from respiratory samples.Although the cause of miscarriage is not identified in ∼50% of cases, nowadays, no systematic diagnostic testing for the presence of <i>W. chondrophila</i> is routinely performed. Implementing large-scale testing in women with reproductive health issues would undoubtedly increase our knowledge of <i>W. chondrophila</i> prevalence and its implications for disease outcomes.