ABSTRACT
The clinical syndrome of pneumonia in adults in Port Moresby, the capital city of Papua New Guinea, has changed from the 1970s to the present. The severe lobar pneumonia commonly diagnosed in young adult men, characteristically from Goilala and living in settlements in Port Moresby, is no longer seen. Today pneumonia in adults is likely to be milder and bronchopneumonic in type. Possible explanations for the change include changes in immunity and in the bacteria found in the environment and carried in the nasopharynx of recent immigrants to the city. A change in treatment-seeking behaviour together with the wide availability of oral antibiotics is considered to be the most likely cause of the altered clinical syndrome that we have observed.