Asthma prevalence was considered to be low in most low-income nations, but numerous studies have shown that this is not always the case. This is a narrative overview of recent articles on the prevalence of asthma in low and middle-income countries (LMICs) and underserved groups in wealthy nations. Several studies have found a low frequency of asthma in LMICs, although it appears to be growing. According to a review of the International Study of Asthma and Allergy in Childhood phase III database, while the incidence of asthma among children and adolescents is higher in industrialized countries, asthma symptoms are typically more severe in less wealthy countries. Secondary examination of data from the WHO’s world health survey, which was conducted among adults in 70 countries, shows that symptoms of asthma are less common in middle-income nations and more common in the extremes, low income and high income. Indeed, new research has linked asthma symptoms in the poor to unsanitary living circumstances, which may lower the likelihood of atopy but raise the risk of nonatopic wheeze. In LMICs, urbanization and exposure to air pollution appear to be contributing to an increase in the prevalence and severity of asthma. Access to correct diagnosis and treatment with asthma controller medicines, particularly inhaled corticosteroids, is possible and cost-effective, reducing symptoms, health resource consumption, improving quality of life, and lowering mortality in low-resource settings.

Asthma prevalence was assumed to be low in low-income nations, but numerous studies have shown that this is not always the case. Underdiagnosis, undertreatment, exposure to air pollution, and unsanitary living circumstances may all contribute to an increase in the frequency and severity of asthma symptoms among the poor. 

Reference: https://journals.lww.com/co-allergy/Abstract/2017/06000/Asthma_prevalence_and_severity_in_low_resource.5.aspx