Exercise-induced bronchospasm among school children in Gusau, Nigeria

Childhood asthma was said to be rare in Northern Nigeria three decades ago. However, since then, there has been rapid industrial development with increase in especially textile and quarry factories. Hyperresponsiveness of the bronchi of asthmatic children to various challenge tests differentiate them from non-asthmatic children. One of these, the Exercise-Induced Bronchospasm (EIB) which is a reduction in post exercise Peak Expiratory Flow Rate (PEFR), is widely used to define childhood asthma in epidemiological studies. To determine the current prevalence of asthma in childhood in a Northwestern Nigerian town, pupils aged 5-14 years were enrolled in the study.

A modified ISAAC questionnaire was administered and the subjects trained to use the peak flow meter. Pre exercise PEFR was obtained thereafter they were subjected to a six minute free running exercise challenge test and the best of three post exercise PEFR taken at intervals was obtained. EIB was taken as 15% reduction or more in post-exercise compared to pre-exercise PEFR.

The prevalence of EIB was 6.0% (64/1067 subjects) while 12.7% (136/1067) had a history of wheeze. History of wheeze was found to be a sensitive (96.3%) but nonspecific (22.2%) indicator of childhood asthma. The highest prevalence of EIB was among children aged 10-14 years with male: female ratio 1.9:1. The location of the residence of the pupils did not significantly affect the prevalence of EIB.

The prevalence of childhood asthma in this region is on the increase compared to earlier studies and there should be a high index of suspicion in children with suggestive symptoms who should then undergo further screening tests.