Epidemiological and clinical aspects on infections due to Chlamydia pneumoniae (strain TWAR).

Recently a new species of Chlamydia has been recognized and named Chlamydia pneumoniae, strain TWAR. This organism has now been causally associated with respiratory infections in humans. Serosurveys demonstrate the universal distribution of this pathogen all over the world. The antibody prevalences increase from a few per cent in pre-school children to 20-30% in teenagers. They then increase at a slower rate with prevalences of 40-60% in adults. Antibodies to the TWAR strains have so far been detected only in humans but not in birds or domestic or pet animals suggesting humans as the sole host for these organisms. The isolation and propagation of the TWAR strains and the development of monoclonal antibodies have made diagnosis of infection by these pathogens possible.