Allergic asthma in developing and developed regions around the globe

Allergic asthma a well-known chronic disease, of heterogeneous nature, affects respiratory airways. It presents several phenotypes on the basis of the disease progress. These phenotypes form recognizable demographic and clinical clusters around the globe. These phenotypes include allergic asthma, non-allergic asthma, late-onset asthma, asthma with fixed airflow limitation and asthma with obesity. Amongst all the different phenotypes, allergic asthma is recognized most easily. It has become highly prevalent since the latter half of 20th century, in both developing and developed nations.

This rising menace of asthmatic allergy in both developing and developed nations requires an in-depth study to determine the significant factors. It demands the exploration of increasing prevalence in nations which differ in socio-demographic, technological, living standards and other measures. Here, the present article throws light on extrinsic or allergic asthma in developing and developed regions. Extrinsic asthma involves exposure to aeroallergens resulting in inflammation of mucosa.

Asthma in developed and developing regions

The spread and diagnosis of asthma assume a complex process, with multifaceted systems for assessment, treatment and management in different nations. Therefore, the task of global level surveillance is even more cumbersome. Hence, it is necessary to periodically assess and document the findings from different studies, reporting relevant results.

Childhood asthma

In developed regions, several studies indicate commonalities of chronic asthma among children. International Study of Asthma and Allergies in Childhood (ISSAC) is the largest study with the purpose of summarizing the prevalence trends on a global level. Currently, in Phase 3, the study surveyed 1,200,000 children from 233 centers around the world in 98 regions. The results of Phase three have shown a global prevalence rate of 14.1% in children belonging to 13-14 years and 11.7% for 6-7 year group. The tables below show asthma prevalence among children in developed and developing continents as given by ISSAC.

Developed Developing
Region Prevalence of current symptoms of asthma (%) Region Prevalence of current symptoms of asthma (%)
Male Female Male Female
North America 19.8 23.3 Africa 14 14
Northern and Eastern Europe 8.9 10.5 Asia Pacific 8.9 8.6
Western Europe 13.8 15 Eastern Mediterranean 10.6 7.9
Oceania 17.2 17.6 Indian Sub-continent 8.6 5.4
Latin America 14.6 17.1

Table 1: Prevalence of current symptoms of asthma in developing and developed regions for 13-14 yr olds (Mallol et al., 2013).

Developed Developing
Region Prevalence of current symptoms of asthma (%) Region Prevalence of current symptoms of asthma (%)
Male Female Male Female
North America 21.5 16.7 Africa 10.8 9.3
Northern and Eastern Europe 9.9 7.5 Asia Pacific 10.8 8.2
Western Europe 10.9 8.3 Eastern Mediterranean 10.3 8.5
Oceania 24.3 19.2 Indian Sub-continent 7.4 6.1
Latin America 18.9 15.8

Table 2: Prevalence of current symptoms of asthma in developing and developed regions for  6-7yr olds (Mallol et al., 2013).

Adult asthma

With respect to the occurrence of asthma amongst adults, the findings from cross-sectional world health survey of 2012 are shown below (Table 3). In the Western Pacific region, amongst the developing regions, Philippines presented highest rate of prevalence, 7.21%. Also, the statistics from developed regions show high asthma prevalence.

Developed Developing
Region Prevalence of doctor-diagnosed asthma (%) Region Prevalence of doctor-diagnosed  asthma (%)
North America 7.7 Africa 3.94
Europe 5.1 Southeast Asia 3.24
Australia 20.96 Eastern Mediterranean 2.93
Latin America 4.27

Table 3: Prevalence of doctor-diagnosed asthma in developing and developed regions for adults (To et al., 2012).

The childhood and adult asthma prevalence rates indicate the high prevalence of the disease in resource-rich regions. However, studies also indicate towards the continued blurring of lines of difference in prevalence between developing and developed regions. The low and middle-income nations are also witnessing an increase in asthma prevalence (The Global Asthma Network, 2014).

In the context of the present discussion, the developing and developed regions present socio-economic and geographical differentiation. Hence, the causative factors of extrinsic asthma in these regions are discussed with respect to the nature of allergen exposure. The epidemiological studies present a range of supporting evidence for different causative factors in different regions.

Causes of allergic asthma in developing regions

Wang et al. (2008) in their study brought out the difference in residing in developed and developing nations. The focus on Chinese population migrating to Canada allowed the identification of asthma prevalence due to environmental factors. Chinese adolescents residing in mainland China showed minimal prevalence, whereas prevalence was higher for China-born migrants. However, the prevalence was highest among those Chinese adolescents who were born in Canada.

It has also been stated that inhabitants of developing nations are more susceptible to allergic asthma as they are exposed to fewer and less diverse microbes. The inhabitants of developing nations on the other hand face higher exposure and thus fewer instances of allergies are seen (Riiser 2015). A study from Pakistan investigating the prevalence of allergic asthma showed no relation between sex and the respective disease. However, the results linked socioeconomic status and atopy with allergic asthma, with high significance (Noori et al. 2007).

Causes of allergic asthma in developed regions

The westernization of environment involving low exposure to infections and allergens besides the high use of antibiotics are seen as prominent reasons for allergic asthma (Bryant & Knights 2014). The exacerbation of asthma in Barcelona, Spain finds its basis in heavy exposure to soybean dust. The cargo handling activities at the local ports result in the release of soybean dust in the atmosphere (Rodrigo et al. 2004). In Germany, the reunification of eastern and western Germany is a proven social factor responsible for a change in the pattern of allergic manifestations. The population shows higher tendencies for house dust mite sensitization, responsible for a steep increase in adults. Being single child in the family is another prominent reason, as shown by vanished west/east difference among children, which is prominent in adults (Krämer et al. 2015).

These findings support the hygiene hypothesis. A research from Tokyo shows that high usage of antibiotics within first 2 years of life, enhances the risk for asthma (Odds ratio = 1.72, CI = 1.10-2.70) (Yamamoto-Hanada et al. 2017). In New Zealand, gender (higher disposition of females), hyper-responsiveness of airways in middle and later childhood and house dust mite sensitization are the causative factors of childhood asthma. Also, New Zealand, Australia, USA, UK, Canada, report seasonal cycles in exacerbation of asthma. The instances of allergic asthma peak during late summer and early autumn times, related with the return to school. In UK and Canada, these exacerbations occur in the first week of September, whereas for Scotland and Sweden the active period is the third week of August (Johnston & Sears 2006).

Factors responsible

The brief examination of the epidemiological literature on the issue of asthma unraveled the differences between developed and developing regions. Both the regions evidently differ from each other in prevalence patterns and the causative factors. The rising urbanization in developing nations, however, is resulting in increasing instances of allergic asthma. This is because people continue to adopt the western style of living. The difference also highlights that it is necessary to practice a balance between lifestyle habits to allow the biological functions to take their natural course of development and action. The western habits of extensive hygiene and antibiotic usage render the body of essential microbial exposure. Therefore, it is necessary to educate people and try to render control over the upsurge of allergic asthma.

References

  • Bryant, B. & Knights, K., 2014. Pharmacology for health professionals, Elsevier Australia.
  • Johnston, N.W. & Sears, M.R., 2006. Asthma exacerbations · 1: Epidemiology. Thorax, 61(8), pp.722–728.
  • Krämer, U. et al., 2015. What can reunification of East and West Germany tell us about the cause of the allergy epidemic? Clinical & Experimental Allergy, 45(1), pp.94–107.
  • Mallol, J. et al., 2013. The international study of asthma and allergies in childhood (ISAAC) phase three: A global synthesis. Allergologia et immunopathologia, 41(2), pp.73–85.
  • Noori, M.Y., Hasnain, S.M. & Waqar, M.A., 2007. Prevalence of allergies and asthma in Pakistan. World Allergy Organization Journal,, pp.S206–S207.
  • Riiser, A., 2015. The human microbiome, asthma, and allergy. Allergy, Asthma & Clinical Immunology, 11(1), p.35.
  • Rodrigo, M.J. et al., 2004. Epidemic asthma in Barcelona: an evaluation of new strategies for the control of soybean dust emission. International archives of allergy and immunology, 134(2), pp.158–164.
  • The Global Asthma Network, 2014. The global asthma report, Auckland.
  • To, T. et al., 2012. Global asthma prevalence in adults: findings from the cross-sectional world health survey. BMC public health, 12(1), p.204.
  • Wang, H.Y. et al., 2008. Prevalence of asthma among Chinese adolescents living in Canada and in China. Canadian Medical Association Journal, 179(11), pp.1133–1142.
  • Yamamoto-Hanada, K. et al., 2017. Influence of antibiotic use in early childhood on asthma and allergic diseases at age 5. Annals of Allergy, Asthma & Immunology, 119(1), pp.54–58.
Yashika Kapoor

Yashika Kapoor

Research analyst at Project Guru
Yashika has completed her bachelors in life sciences and holds a masters in forensic sciences. Being a major in forensic biology, she is trained in techniques of DNA extraction and sequencing. She also has hands on experience of dealing with sensitive evidences and case files. She aims at developing her knowledge base through fact based learning. With a penchant for reading, and writing, she likes to keep her facts concrete. She is a confident person and aims at achieving perfection in every task assigned to her. She aims at securing a place in her professional life which allows her to explore different areas relevant to her field of work. Along with academics, she is a creative soul. Food, art and craft are some of her other passions.
Yashika Kapoor

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