Study of antibodies against viruses, chlamydiae, rickettsiae and Mycoplasma pneumoniae in children with respiratory diseases.

: Seroconversion to different viral, chlamydial, rickettsial and mycoplasma antigens was followed up in 134 children aged 0-6 years, hospitalized with different respiratory diseases. Parainfluenza viruses type 1, 2 and 3 and adenoviruses appeared to be involved in the etiology of most of the cases; respiratory syncytial virus was often found to play a role in pneumonia/bronchopneumonia and in "influenza-like illness", while chlamydiae and M. pneumoniae could be incriminated in cases of "influenza-like illness", as well as in the other categories of respiratory disease. Mixed infections with the agents studied could be detected.