Urbanization and childhood asthma: an African perspective.

The increasing prevalence of childhood asthma in the developed world is a cause for concern. Much research is currently being conducted in an attempt to identify possible reasons for this occurrence. A so-called Western lifestyle has been the factor most commonly cited to explain this worrying increase in asthma prevalence. In essence, this implies a way of life where children are exposed from early infancy to a wide range of foods, infections, indoor and outdoor allergens, and irritants and to the effects of motor vehicle pollution. Until fairly recently, children in many African countries lived mainly in rural areas and were not exposed to the effects of a Western lifestyle. Early studies in a limited number of African countries showed a very low rural prevalence of childhood asthma, especially where children lived according to a traditional lifestyle. These same studies showed that asthma was not uncommon in urbanized African children. There has been an increasing tendency over the past 20 years for those in rural communities to move to the large urban centers. More recent childhood asthma prevalence studies, especially those from Kenya and Ghana, have confirmed the urban-rural differences but have shown a much narrower gap. In part this may be the result of exposure of rural children to agricultural pesticides and irritants as well as of an increasing tendency to adopt a more Westernized lifestyle such as the use of beds with mattresses, pillows, and blankets. These circumstances on the African continent provide a natural laboratory in the quest for factors that influence the development of asthma in susceptible children. Once more fully elucidated, it is possible that much valuable information will be available to combat the relentless increase in childhood asthma both here as well as in the developed world.