Asthma is globally one of the most common childhood chronic disorders associated with significant hospitalization and school absenteeism [1, 19]. Therefore, it is important for countries to establish reliable data on the prevalence of childhood asthma, and to institute effective interventions to reduce the economic and social costs associated with childhood asthma.
This study compared the prevalence of childhood asthma among secondary school pupils in both rural (Bagamoyo) and urban (Ilala) districts along the Indian Ocean coastline of Tanzania. The study has shown that asthma was more prevalent among pupils living in urban areas than among those living in rural areas. Although the magnitude of differences varied, this rural–urban difference in prevalence has also been reported in other studies [8, 9, 20, 21]. The 6.6% prevalence for self-reported asthma in the rural pupils in this study is comparable to that reported from other parts of Africa, India, and tropical countries [2, 6]. Similarly, the high prevalence of 17.1% for self-reported asthma in the urban pupils from Ilala is comparable with that reported from both the western world and other African cities [2, 8, 22]. In the ISAAC study, similar prevalence rates were reported among 13 to 14 year-old pupils in Cape Town (20.3%), Polokwane (18.0%), Reunion Island (21.5%), Brazzaville (19.9%), Nairobi (18.0%), Urban Ivory Coast (19.3%) and Conakry (18.6%) . However, the reported prevalence rates for both urban and rural self-reported asthma in our study are higher than the prevalence of 1.9–5.2% that was previously estimated in Tanzania in 2004 . This discordancy is probably due to time and methodological differences between the two studies. Nonetheless, the prevalence of wheeze in the past 12 months for the rural pupils in the current study is comparable to that reported among 9–10 year old children in Northern Tanzania .
Exercise tests have been widely used in the diagnosis of asthma in children [21, 24]. Although a negative test does not automatically rule out asthma, a drop in the peak flow rate of 20% of the resting rate is considered positive . Falls in peak expiratory flow rates of 10%, 15% or even a 25% have also been used to define exercise-induced asthma in some studies [18, 21, 24]. The use of different cut-off values has not only contributed to the variation in the reported prevalence rates of exercise-induced asthma, but has also rendered comparison of findings from these studies problematic. Using a 20% fall in PEFR, the prevalence of asthma in rural Bagamoyo and urban Ilala is 2.3% and 6.4%, respectively. On the other hand, using a 15% fall in PEFR as the criteria for diagnosis of childhood asthma, the prevalence in our study increased to 4.3% and 7.2% for rural and urban areas, respectively. These rates are higher than the prevalence rates reported in a South African study that used a 15% drop in PEFR to define exercise-induced asthma and found prevalence rates of approximately 3% in urban children and 0.1% in rural children . Similar to other studies, we found a rural–urban difference in the prevalence rates of exercise-induced asthma [7, 21, 24].
In this study, the majority of pupils had received information about their asthma status from parents and health facilities. A surprising finding of our study was that schools were not significant sources of the pupils’ information about causes and pathophysiology of asthma. The findings suggest that there are gaps in the secondary school curricula regarding asthma education, an issue that needs to be revisited.
Our study also reports varying perceptions about asthma among the studied pupils, suggesting pupil belief that asthma is an infectious disease. These perceptions may be related to our additional finding that non-asthmatic pupils fear playing, eating with, or sleeping in the same room with asthmatic pupils. These observed perceptions suggest inadequate or deficient knowledge about the causes and pathophysiology of asthma on the part of the study’s pupils. The non-asthmatic pupil’s fear of their peers with asthma was found to be more pronounced among rural rather than urban pupils, a finding that may be explained by differences in socio-cultural values and access to information about asthma. Parents have been reported to play an important role in shaping the health care behaviour and beliefs of pupils. However, most parents are likely to share their own cultural norms, prejudices, fears, and beliefs. Teachers on the other hand, because of their intense and prolonged contact with pupils during the school year, are in a better position to be an important source of information about asthma. Nonetheless, teachers may not be able to provide such valuable health information, because they teach according to standard curricula, which may not include information about asthma or because of their own ignorance and/or personal beliefs about the disease. In this regard, provision of correct information to parents and teachers about childhood asthma may alleviate the fears many pupils may have about this common childhood condition.