Asthma and chronic airflow limitation in the highlands of Papua New Guinea: low prevalence of asthma in the Asaro Valley.

The prevalence of asthma in the South Fore region of Papua New Guinea was found to be 7.3%, which is thought exceptionally high for highland areas in this country. To investigate the prevalence of asthma and of chronic airflow limitation in a different highland region with similar living conditions, adults and children from 7 villages in the Asaro Valley were interviewed. Questions were asked about smoking history and about past and present symptoms of cough, of shortness of breath, of chest tightness and of asthma. Of 743 adults interviewed, 206 underwent a clinical study with measurements of lung function, bronchial responsiveness and skin prick tests. Dust was collected from the floors and blankets of 36 houses for counts of house dust mites. We did not find any children with symptoms of asthma. Only 2 adults (0.3%) had symptoms consistent with asthma, and a further 6.2% had symptoms and/or lung function consistent with chronic airflow limitation. Most bronchial hyperresponsiveness was associated with asthma or with chronic airflow limitation. The prevalence of atopy was similar in the Asaro and South Fore populations, but the South Fore had higher house dust mite counts in blanket dust. The low prevalence of asthma in the Asaro Valley is unexplained in terms of factors normally associated with asthma. Because asthma in this area does not appear in childhood and only develops in a small proportion of adults, it may be of different aetiology to asthma in Caucasian populations.