Asthma, the bane of modern life, stalks the young ones and the affluent. It will strike 32 million people in India by 2010. The silent strangler has a propensity to waylay its victims, striking with stealth. An analysis into what triggers the killer which garrottes nearly 500 victims every day and leaves several others suffering a life of anticipated terror
LIKE A FISH out of water, she chokes and gasps. Writhes. She struggles to snatch a lungful of air, while watching television she suddenly hits a vacuum. She is asthmatic. She is just about anybody. One of the 150 million that are reminded the hard way that life in today's world is just a breath away from turning into a statistical entry in the death register.
But asthma doesn't discriminate, not between sexes, at least. She could just as well be a boy. The medical fraternity is sure though, asthma does prefer the affluent and the children of affluence, more so. It is the curse of modernity. A morbid attendant at the door to the new world, waiting to catch the entrant unawares. A murderer that chokes 180,000 people to death each year. And the lists of its victims only grow longer each year with humans increasingly embracing a lifestyle that is too cushioned to resist the onslaught of allergen. Doctors try to fathom the method to the madness, predict a trend. But trends emerge as chaotic as the life of an asthmatic.
If you are not an asthma patient here's how you can experience the misery of one: take a deep breath. No, do not exhale. Not just now. Hold it for 20 seconds. Now exhale. But only for two seconds. Inhale again, holding it this time for 15 seconds. Repeat this for intervals by holding your breath for 10-15 seconds more. Never before did oxygen feel this precious. To slip from the precipice into an abyss, just about. To be pulled back, finding your feet grounded again, only to fall back once more. Repeatedly. Millions of people, often children, regularly endure this near death experience. Attacks occur suddenly, without any provocation. Today in India, about 15-20 million asthmatics daily live this encumbering reality. One out of 10 children in the country are asthmatic. In Delhi alone 700,000 people live under the spectre of asthma.
Asthma is more prevalent in Australia, the UK and New Zealand. In the US, asthma cases have shot up by 75 per cent between 1980 and 1994. The disease kills 5,000 US citizens each year. The rates of affliction are much lower in Asia - about eight per cent on an average, compared to the global average of 14 per cent. Across countries in Asia, and within each country, significant variations exist.
But experts are unanimous that in case of India the disease is one of the most underreported ones. In fact, nine out of 10 cases of asthma in children go undetected say some guesstimate. And while children may be the primary targets, asthma in adults too seems to be on the rise. The British Medical Journal reports on a Scotland-based study that showed asthma in adults to have doubled in the past two decades.
Baffled by figures
And the rate of those inflicted with the debilitating disease increases by 12 per cent every decade. This is the world average and it is a conservative figure. Real figures, however, may never emerge. Diagnosing asthma is never easy.
A plethora of triggers bring the disease into play. Just as the number of those afflicted rises, so does the list of triggers. Environmental triggers like diesel, lifestyle-related ones like junk food consumption - the range is maddening and frustrating for the patient, the doctor and the researcher.
In India, data on asthmatics is not collected officially. The data bank created could help find patterns - trends that help focus medical and pharmacological research. So a comprehensive picture of the disease continues to elude experts. Elsewhere, there is a great wealth of research on asthma, but with little consensus. Some report that smoking, exposure to allergen, dust mite or cockroaches cause asthma. Others report that there is a genetic link. While one section of the research looks for reasons behind asthma's spread, the other tries to find cures and disease mitigating drugs.
An asthmatic, trying to figure out just what triggers the spasmodic dance of the devil inside, cannot wait for a medical breakthrough or a cure. The asthmatic learns to live with whatever drug regime is affordable, whatever provides some solace. This moment.
Asthma is easily caused. Innumerous allergen, from pollen grains to dust mite, play havoc, exacerbating the disease. While experts are unable to reach a consensus, one thing's clear: modern lifestyle contributes to this disease
ASTHMA affects people of all ages, runs in families and can be severely debilitating, even fatal. It picks on the vulnerable children. Recent research suggests that genetic, lifestyle, medical and environmental factors combine together, often inextricably, to cause asthma. This is undisputed. Researchers are now investigating other triggers and risk factors such as family size, exertion, housing, socioeconomic status and allergen in air and food that contribute to its onset and severity. Genetic causes
ATOPY: The propensity, usually genetic, for developing immunoglobin E (IgE) mediated responses to allergen is probably the strongest identifiable risk factor for asthma development. A review of clinical evidence by Adnan Custovic of Wythenshawe hospital in the UK in 1998 showed most asthma patients to be atopic - they are prone to producing abnormal amounts of IgE when exposed to allergen like domestic mite, animal proteins, pollen and fungi. Atopy occurs in 30-50 per cent of the population, but overall asthma prevalence is usually much lower. In other words, most asthmatics are atopic but only some with atopy will develop asthma. Yet, when expressed in the lower airways, atopy remains among the strongest predisposing factors for developing asthma. J K Suri, head of respiratory medicine at Safdarjung Hospital, Delhi, says, "While environmental factors aggravate asthma, they cannot be supported without a strong genetic base."
ETHNICITY: Asthma occurs among all races. Yet marked ethnic differences have been observed. Minority groups are not only asthma-prone, they also are more likely to die. African Americans are 2.5 times more likely to die of asthma than whites. Puerto Ricans have asthma rates 2-3 times more than whites while, paradoxically, Mexican Americans have rates significantly lower than whites, says Malcolm Blumenthal, a professor of medicine at the University of Minnesota-Twin Cities. Another study observed that in the group aged 5-34 years, asthma mortality rates were 0.5 per 100,000 in Chinese, 1.3 per 100,000 in Indians, and 2.5 per 100,000 in Malay subjects. Similar variations were seen for other age groups. In the 1960s, there was a rise in death rates in New Zealand, Australia and the UK, and a decade later a second epidemic of deaths was observed in New Zealand disproportionately affecting Maoris. Scientists suggest western lifestyle may partly explain such differences, but exact reasons remain unknown.
AGE AND GENDER: That children are becoming increasingly vulnerable to asthma is now confirmed. But the reasons are poorly understood. Childhood asthma is more prevalent in boys than in girls. However, this increased risk seems more related to narrower airways and increased airway tones in boys, which predispose them to enhanced airflow limitation.
GROWTH OF THE CHILD: Asthma evolution depends on the age of onset and possibly on the etiology of the disease. Disproportionate foetal growth (large head and small trunk), that is often associated with a birth weight of less than 2,500 gramme may carry an increased risk of developing asthma during childhood or adolescence. Poor nutrition in underweight babies may also impair basic immunological mechanisms. There is a correlation of early wheeze with reduced lung function before the development of symptoms suggesting that small lungs may be responsible for some infant wheezing that resolves with the child's growth. Asthma may disappear in 30-50 per cent of children at puberty, but often reappears in adult life and up to two-thirds of children with asthma continue to suffer through puberty and adulthood.
AFFLUENCE: The prevalence of childhood asthma and atopy varies widely between countries. Alistair Stewart doing a study for the International Study on Asthma and Allergy in Childhood (ISAAC) studied the correlation between gross national product (GNP) and the symptoms of asthma and other allergies in children from across 56 countries. A moderately strong correlation was established between GNP per capita and the prevalence of asthma. This means the more the income per capita, the greater the prevalence of asthma.
High-income countries like the US, Canada, New Zealand, Australia and the UK have an asthma prevalence rate of between 20-30 per cent in these age groups. Many Latin American countries like Brazil, Costa Rica and Peru have an unusually high prevalence rate of around 20 per cent. Though India and China have a lower prevalence rate (between 4.2-6 per cent), the total number of asthmatics is very high. Also asthma cases are underreported and poorly diagnosed in India and China because of the stigma attached to the disease.
Writing in Thorax, a medical journal published from the UK, Adeola Olusola Faniran compared the prevalence of symptoms in Australian and Nigerian children and found that wheeze and persistent cough were less prevalent in Nigeria (10.2 per cent and 5.1 per cent respectively) than in Australia (21.9 per cent and 9.6 per cent, respectively). Though there was no significant difference in the overall prevalence of atopy between the two countries (Australia 32.5 per cent, Nigeria 28.2 per cent), atopy was a strong risk for wheeze in both countries. Despite this, Australian children had a higher prevalence of asthma symptoms. This could be related to various environmental factors, allergen exposure or to different racial susceptibility, genetic predisposition and environmental factors.
But the story is not as simple as it sounds. Hospital records suggest that people of low socioeconomic status (SES) experience higher mortality and morbidity in comparison with people belonging to higher SES. A study done in London found the severity of asthma cases being more prevalent in the poorer sections. The poor seek treatment and admission only when there is a crisis. They rarely follow a planned treatment procedure and are under-users of primary healthcare facilities. The attendance rate in casualty departments by the poor during acute asthma attacks is four times more than other user groups. Evidently, while the poor may suffer lower incidence of asthma, when the disease does strike, it leaves them in a worse situation than the rich.
Another study shows how the prevalence of severe asthmatic crisis increases inversely with the declining SES of the patients. In Korea, mortality avoidable by medical intervention, defined as 'mortality wholly or substantially avoidable by adequate medical care' decreases with the growth in socioeconomic conditions and health services. These studies show that inequalities in health do exist. Are the poor more susceptible and more exposed to trigger agents? If so, is it possible to modify some of these determinants of disease severity? But how does this conform to the findings of the ISAAC study on the inverse correlation between income (GNP terms) and asthma prevalence? It is time to design our health policies based on epidemiological studies and demographic distribution.
SMOKING: There is now proof that while passive smoking causes increased incidence of wheezing illnesses in the first few years, it does not increase the risk of sensitisation to common aeroallergens, an important risk factor for asthma that onsets later. Surveys show that wheeze and asthmatic attacks are more prevalent in children whose parents smoke.
DIET: The role of dietary factors is under scrutiny, but no clear results have emerged. A recent paper in Thorax by Nariman Hijazi investigated dietary and other factors for asthma in Saudi Arabia where major lifestyle differences are found in different communities. It found that family history, atopy and eating fast food were significant risk factors for wheezy illness, as were the lowest intakes of milk and vegetables and of fibre, vitamin E, calcium, magnesium, sodium and potassium. Studies show that low intake of fish may weaken asthma resistance and evidence suggests that intake of omega-3, a fatty acid found in fish oil, may help keep the disease away.
It is also widely believed that food allergies are common asthma triggers, though evidence is rare. Some food and additives, including salicylates, food preservatives, monosodium glutamate and some food-colouring agents, cause asthma symptoms in some patients.
OBESITY: Obesity is associated with asthma symptoms regardless of ethnicity. The association is consistent with the basal metabolic rate because obese children are more advanced in their maturation than other children. There is some evidence that this association is stronger in girls than in boys.
ALLERGIES: The most important allergen are probably inhaled allergen, like mite, fur of animals, fungi and pollens. Allergen sensitise atopic persons by stimulating the development of specific T lymphocyte cell clones and the production of specific IgE antibodies. Once a person is sensitised (that is, has developed memory T lymphocytes and specific IgE), they are likely to develop allergic inflammation upon re-exposure to the same allergen.
The introduction of mite, the presence of large numbers of insects and cockroaches in tropical countries are some important episodes in the history of asthma. Climate is important because it is directly related to the amount of allergen present in the environment. For example, a damp and warm climate is favourable to mite and mould growth. Sensitisation to allergen by exposure to sources like house-dust mite, cats, dogs, cockroaches and smoke is strongly established, while other factors are less strongly correlated.
According to S K Kabra, an asthma specialist with the All India Institute of Medical Sciences in Delhi, in the general population of India, 60 per cent of the patients suffer from asthma due to viral infections and 40 per cent of the cases are due to allergen, pollens or seasonal variations.
URBANISATION: Universally, levels of asthma in urban communities seem to be higher than in rural ones. Yet, urbanisation involves so many changes in environment and lifestyle that a definitive explanation for this has so far been elusive. Urbanisation with accompanying pollution appears to be more directly related to increase in allergy. For example, in polluted Swedish and Chilean cities, asthma has increased drastically in the last two decades. In Japan, the increased allergy to Cryptomeria japonica, soft wood pine, has been attributed to sensitisation to urban diesel exhausts.
The trigger happy asthma needs just as many treatments to catch it before it hits hard and to limit its effects.It is, one must remember, controllable, even if not completely comprehensible.
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