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A general pattern of factors influencing development of asthma seems to be emerging, including family allergy history/ asthma genetics, smoking, diet, obesity, and inactivity, all of which seem to influence the development of asthma and disease outcomes (Table bellow).

Many clinical or area studies have reported substantially higher rates of asthma prevalence, hospitalization, and mortality among racial and ethnic minorities. However, asthma is also most common among low socioeconomic groups, regardless of race. While black children have higher rates of asthma than white children, most studies have found that black race is not a significant correlate of asthma after controlling for location of residence and socioeconomic status (SES). The basis for the effects of poverty and urban residence on asthma prevalence is not known. One potential asthma factor is allergen exposure and allergen sensitization are common in urban environments. Black children in inner city Atlanta are exposed to high levels of dust mites and cockroach allergen, and a high proportion of the children with asthma were sensitized to these allergens. Litonjua and colleagues also concluded that a large proportion of racial/ethnic differences in asthma prevalence can be explained by factors related to income, area of residence, and level of education.

Asthma Factors that Influence Disease Development and Severity

Income is a determinant of access to health care, and frequently, the quantity and quality of health care available. Persons who have low income, regardless of race or ethnicity, are more likely to be uninsured, to encounter delays or be denied care, to rely on hospital clinics in emergency departments for health services, and to receive substandard care. The usual socioeconomic indicators, education and personal or household income, serve only as surrogates for more complicated correlates of individuals within populations and multiple asthma factors that can impact both on prevalence of asthma and adverse outcomes from the disease.

Studies from Germany comparing the populations of East and West Germany have shown the prevalence of hay fever and asthma as significantly higher in West German children, suggesting that asthma environmental factors explain the difference in prevalence in these ethnically similar populations. Early exposure to infections (as with being in a day-care environment early in life) or exposure to endotoxin (as with growing up on a farm with close exposure to the farm animals) are associated with a decreased prevalence of asthma. In contrast, growing up in an urban environment or generally with an increased standard of living are associated with an increased prevalence of asthma. Such correlates are also present for atopic disorders other than asthma. In fact, Strachan, who noted that prevalence of hay fever was inversely related to family size, was the first to recognize the importance of early exposures on atopic disease. In the USA, asthma is more prevalent in African-Americans and Puerto Ricans. These findings are not explained by the observations on the role of social class in European studies. Given the ethnic differences between African-Americans and whites, these studies may represent gene-by-environment interaction producing varied phenotypic outcomes.

One especially favored target for immune recognition is bacterial lipopolysaccharide (LPS). This macromolecule is found only in the outer lipid bilayer that surrounds the cell walls of gram-negative bacteria, such as Neisseria, Salmonella, and Escherichia coli. Each molecule of bacterial lipopolysaccharide consists of a core carbohydrate linked on one side to a phospholipid (called lipid A) that is anchored in the bilayer and on the other side to a long polysaccharide chain (called the O sidechain) that extends outward from the bacterial surface (Figure 1 bellow). The sequence of sugars making up the O sidechain is species-specific and highly variable, even within a single bacterial genus: For example, more than 1000 variants in Salmonella are known. (more…)

Asthma is a complex syndrome rather than a single disease entity. Different phenotypes with varying prognosis and determinants have been described, particularly over childhood years 2 and will be discussed in detail in the following. For example, transient early wheezing is characterized by the occurrence of wheezing in infants up to the age of 2 to 3 years which disappears thereafter. The main predictor of these wheezing illnesses is premorbid reduced lung function before the manifestation of any wheeze. These decrements in pulmonary function are in part determined by passive smoke exposure in utero 4 and result in symptoms of airway obstruction when infants get infected with respiratory viruses. (more…)

Natural history studies with the following design features provide a firm epidemiologic foundation for risk factor assessments and etiologic hypotheses:
(1) long-term cohort studies of a prospective design minimize biases resulting from poor parental recall;
(2) multiple evaluations over time provide important checkpoints during the dynamic period of childhood growth and development; and
(3) the inclusion of objective disease measurements strengthens these studies by validating subjective disease assessments (i.e. questionnaire data). (more…)

The effects of exposure to environmental tobacco smoke (ETS) on children have been extensively studied and numerous surveys have consistently reported an association between environmental tobacco smoke exposure and respiratory diseases or respiratory allergies. Strong evidence exists that passive smoking increases the risk of lower respiratory tract illnesses such as bronchitis, wheezy bronchitis and pneumonia in infants and young children. (more…)

According to the National Survey of Children in the United States, the prevalence of asthma was 15% (last 12 months), that of hay fever was 12.4%, of skin allergy 9.8% and digestive/ food allergy 3.6%. Overall, every fourth child is affected (25.4%). Regarding the diagnosis of asthma in children, the prevalence, for instance in Germany, rose from 1.25% to 2.21% between 1951–1952 and 1964–1965. For the last 10 years there has been dispute about whether the increase in asthma and allergy has come to a halt. However, the observation period is too short to draw any conclusion. A study of adults went beyond this simple dispute and investigated age and cohort effects for immunoglobulin E (IgE) sensitization from 1992 to 1998–2002. (more…)

The most crucial element in the assessment process of a possible allergic problem is patient’s allergy history. An allergy history is made up of a chief problem, resolve of seasonality or diurnal variation of symptoms, detection of triggers, occupational asthma exposure, and reaction to medicines, family history, and some other relevant medical history. An allergy history looks for to define the patient’s chief complaint(s) and concentrates on the details with regards to those complaints. There is a lexicon typical to patients with allergy complaints. Sinus dizziness strain and headaches are often cited as symptoms. The history taker should be attuned to the patient’s viewpoint as a possible allergy sufferer. Exactly where and when does the symptom happen? Or is it happened during sleep? (more…)

To prevent the development of allergy, allergen avoidance has to be instituted before sensitization has occurred. The specific type of aero allergens may vary depending on the climatic and economic situation. For example, House Dust Mite is the most important allergen in humid climates and pet allergens assume importance in cold countries, while cockroach allergen is the major sensitizing agent in crowded, inner city areas. Several large prospective studies have instituted House Dust Mites avoidance measures during pregnancy, at birth and later in childhood, and assessed children for asthma and allergic manifestations. (more…)

Atopic Dermatitis is considered to be one of the first manifestations in the atopic march. The aim of this study was to investigate prospectively the natural course of Atopic Dermatitis to determine factors influencing its prognosis and to analyse the relationship of Atopic Dermatitis with childhood asthma. The Multicenter Allergy Study, a German birth cohort, followed 1314 children from birth to age 7 years. Physical examinations, parental interviews on atopic symptoms and diagnoses, and determination of specific immunoglobulin (Ig)E levels were performed regularly. (more…)

Epidemiological studies of farm children are of international interest because farm children are less often atopic disorders, have less allergic disease, and often have less asthma pain than do non-farm children—findings consistent with the hygiene hypothesis. The investigators studied a cohort of rural Iowa children to determine the association between farm and other environmental risk factors with four asthma outcomes: (more…)