Why is prevalence of asthma increasing

Strachan, a British epidemiologist who was studying hay fever. The more children in a family, he noticed, the lower the rates of hay fever and eczema, an allergic skin condition. Children in large families tend to swap colds and other infections more often than children with fewer siblings. Could it be that increased exposure to pathogens from their many siblings was protecting children from large families against allergies?

That same year Erika von Mutius, an epidemiologist at Munich University, was looking into the effect of air pollution on asthma in what was then East and West Germany. Children from dirtier East Germany, she was shocked to find, had dramatically less asthma than their West German counterparts living in cleaner, more modern circumstances. The East German children, unlike their Western counterparts, had spent more time in day care and thus had likely been exposed to many more viruses and bacteria.

These findings sparked intense debate among scientists. What is it about unhygienic living that might protect against asthma? These two groups of cells produce chemicals that inhibit each other. Early-childhood exposure to bacteria and viruses would cause the infection-related cells to become active, keeping the allergy- and parasite-related cells in check. Inconvenient Facts There was only one problem. As more data came in, they failed to tell the same story as the hygiene hypothesis.

Children in Latin America with high rates of supposedly protective infection have even higher rates of asthma than children in western Europe. Inner-city children in Chicago and New York have quite high rates of asthma, despite unhygienic living.

And the rates of asthma varied among countries with very similar histories of cleanliness—indicating that there was more to it than tidiness. In addition, research showed that the relation between asthma and allergy is not at all straightforward. Some cases of asthma are indeed triggered by allergies, although the consensus among researchers over the past decade is that the connection is probably not as clear-cut as the hygiene hypothesis would suggest. Still other layers of immune regulation must be involved.

Maria Yazdanbakhsh, a parasitologist at Leiden University in the Netherlands, has shown that people infected with parasitic worms have very high levels of the allergy-related immune cells but very low rates of asthma, disproving a direct connection between allergy and asthma in these cases at least.

What is more, a landmark review of asthma studies in by Neil Pearce, now at the London School of Hygiene and Tropical Medicine, demonstrated that at least half of asthma cases in the general population have no connection to allergic reactions at all.

This review focuses mainly on studies of asthma prevalence and symptoms among adults. Parallel with increased urbanization, we can assume that the increase in asthma prevalence in most areas of the world will continue. However, in Australia and North-West Europe studies performed, particularly among children and adolescents, indicate that the increase in asthma prevalence may now be leveling off. Acta Paediatrica. Sheikh A and Simpson CR. Trends in the epidemiology of asthma in England: A national study of , patients.

Journal of the Royal Society of Medicine. An estimate of asthma prevalence in Africa: A systematic analysis. Croat Med J. Significant rise of the prevalence and clinical features of childhood asthma in Qingdao China: Cluster sampling investigation of 10, children. Definition of critical asthma syndromes. Clin Rev Allergy Immunol. Prevalence of uncontrolled severe persistent asthma in pneumology and allergy hospital units in Spain. J Investig Allergol Clin Immunol. Current and emerging treatments for severe asthma.

Journal of Thoracic Disease. Trends in asthma morbidity and mortality. September Increasing U. National surveillance for asthma—United States—— October 19, ; 56 SS08 : 1—14, 18— Risk factors for recurrent asthma hospital visits and death among a population of indigent older adults with asthma. Ann Allergy Asthma Immunol. Patterns of hospitalization in elderly patients with asthma and chronic obstructive pulmonary disease. Bahadori K and Doyle-Waters M. Economic burden of asthma: A systematic review.

BMC Pulm Med. Maslan J and Mims JW. What is asthma? Pathophysiology, demographics, and health care costs. Otolaryngol Clin North Am. Emergency department charges for asthma-related outpatient visits by insurance status. J Health Care Poor Underserved. Asthma in the US. Accessed April 1, The costs of asthma in Poland in Pol Merkur Lekarski.

Fx Currency Exchange. Foreign currency exchange rates and currency converter calculator. Saving in medical costs by achieving guideline-based asthma symptom control: A population-based study. Costs associated with workdays lost and utilization of health care resources because of asthma in daily clinical practice in Spain.

Asthma in the global NCD agenda: A neglected epidemic. Lancet Respir Med. Interaction effect of psychological distress and asthma control on productivity loss? Asthma costs and social impact.

Asthma Research and Practice. Global Strategy for Asthma Management and Prevention available at: ginasthma. Accessed May 5, A year asthma programme in Finland: Major change for the better. Enilari, O. Annals of Global Health , 85 1 , p. Enilari O, Sinha S. Annals of Global Health. Annals of Global Health , 85 1 , 2. Enilari, Oladunni, and Sumita Sinha. Annals of Global Health 85 1 : 2. Annals of Global Health 85, no.

Enilari, Oand S Sinha. Annals of Global Health , vol. Start Submission. Abstract Asthma is a disease characterized by chronic airway inflammation, leading to intermittent symptoms of wheeze, dyspnea, cough and chest tightness in combination with variable expiratory airway obstruction.

How to Cite: Enilari, O. Published on 22 Jan Peer Reviewed. CC BY 4. Introduction Asthma is a disease characterized by chronic airway inflammation, leading to intermittent symptoms of wheeze, dyspnea, cough and chest tightness in combination with variable expiratory airway obstruction [ 1 ]. Global Epidemiology of Asthma Accurately estimating the incidence and prevalence of asthma on a global scale is challenging because the diagnosis is often based on survey responses to questions about relatively non-specific symptoms which are open to subjective interpretation [ 11 , 12 , 13 ].

Figure 1 Prevalence of symptoms of asthma in the past 12 months among persons aged 18 to 45 years in 70 countries, Worlds Health Survey — Source: To T, et al. BMC Public Health Figure 2 Age-standardised asthma mortality rates for all ages — from countries where asthma is separately coaded as a cause of death, ordered by mortality rate and country income group. Cost of Asthma Care Among chronic diseases, asthma is one of the main contributors to increased health care expenditures Table 1 [ 39 , 45 ].

Adapted from Serra-Battles J, et al. Eur Resp J. Strategies to Reduce Asthma Burden Strategies have been implemented globally to reduce asthma burden [ 3 ]. Conclusions Asthma is still a highly prevalent chronic disease that contributes to preventable healthcare resource utilization throughout the world.