A review of zoonotic chlamydiae species in Africa: assessing their burden and potential impact through One Health perspective

Chlamydia species, a group of obligate intracellular Gram-negative bacteria, affect humans, livestock, companion animals, and wildlife, with infections ranging from asymptomatic to severe depending on host species and strain. Diagnosis can be difficult due to mild lesions or co-infections. Because Chlamydiaceae infect multiple hosts, a One Health approach, integrating human, animal, and environmental health is essential for effective control and prevention. C. trachomatis remains endemic in many regions, while Chlamydia pneumoniae is implicated in community-acquired pneumonia. C. abortus threatens livestock and people in pastoralist communities. Other species, including C. caviae, C. felis, C. muridarum, C. pecorum, and C. psittaci, cause high morbidity in animals, and many are zoonotic, posing risks to humans through cross-species transmission. Closely related Chlamydia-like bacteria also pose emerging threats in both human and animal populations. In Africa, diverse ecosystems facilitate frequent cross-species contacts that can drive disease emergence. Rapid urbanization, population growth, and widespread poverty increase transmission, while political instability and food insecurity reduce public health responses. As the continent faces a disproportionate burden of emerging and re-emerging infections, strengthening surveillance and targeted interventions is crucial. This review examines current knowledge on the transmission dynamics and public health implications of Chlamydiaceae species in African settings.