Chlamydia pneumoniae Infections in Norway 1981–87 Earlier Diagnosed as Ornithosis

Abstract

Ornithosis has been a notifiable disease in Norway since 1957. During an outbreak of respiratory disease in 1981–82, described as ornithosis, contact with birds was stated in only 50% of the cases, suggesting that the infection was spread by interhuman transmission. A similar outbreak occurred in the western part of Norway in 1987. Serum specimens from altogether 260 patients, collected during the outbreaks in 1981–82 and in 1987, were investigated for antibodies against Chlamydia pneumoniae (strain TWAR). Evidence of recent infection with C. pneumoniae was found in 67.7% of the cases. The results indicate that the increased incidence of ornithosis in 1981–82 and in 1987 was due mainly to C. pneumoniae infections.