Prevalence, natural history, and relationship of wheezy bronchitis and asthma in children. An epidemiological study

Mycoplasma pneumoniae: acute illness, antibiotics, and subsequent pulmonary function

One hundred and eight children presenting with Mycoplasma pneumoniae infection were assessed during the acute illness and followed for three years. The incidence of wheezing with the acute infection (40%) was greater than expected in a normal childhood population. The initial illness precipitated wheezing for the first time in some subjects but others wheezed only with the acute illness. In non-asthmatic subjects significant bronchodilator responsiveness was present one month after infection. Children given erythromycin during the first seven days of their illness had a significantly shorter fever duration compared with those treated inappropriately. No significant effects of treatment were noted on pulmonary function three years later but non-asthmatic children had abnormal mean forced expiratory volume in one second and forced expiratory flow after 50% of the expired vital capacity compared with 64 healthy controls. These findings indicate impaired function three years after initial infection.

Respiratory symptoms in Tasmanian adolescents: a follow up of the 1961 birth cohort

The 1961 birth cohort of Tasmanians (n = 8410) was initially surveyed in 1968 and was followed up in 1974 for the history and presence of respiratory symptoms and signs. The study was designed to describe and compare the natural histories of wheeze and productive cough. In 1981 a 10% stratified random sample of the original cohort was again followed up and this sample's responses were compared across the three surveys. Wheezing was found to be more persistent than productive cough. Wheezers were twice as likely as coughers to persist with their symptoms to the age of 20. These persistent wheezers represented 3.6% of the cohort available for follow-up in 1974 (n = 7132). Wheezing was also invariably associated with decreased spirometric performance, particularly FEV at 0.5 s and FEF 25-75. The new wheezers first detected in 1974 had had significantly decreased spirometry measurements in 1968 compared to those of their coughing or symptom-free peers. An early history of cough was associated with triple the incidence of wheeze in previously asymptomatic children. Hayfever and eczema were associated with persistence of wheeze. A child with either of these diagnoses was four times as likely to persist in wheezing to the age of twenty than a wheezer without atopic complaint. No significant associations could be demonstrated between wheezing and smoking.

Immediate hypersensitivity, IgE and asthma

Twenty-one asthmatic and twenty-two non-asthmatic children and nine asthmatic adults from two different rural areas of Tanzania, and eight asthmatic children from Dar-es-Salaam were surveyed by questionnaires, skin testing and the measurement of serum IgE. Asthma was significantly commoner in female rural children (four males, fifteen females). The rural asthmatic children apparently had less skin reactivity (in seven of nine tests) and lower specific (in two of four tests) and total serum IgE than age-, sex- and village-matched controls. This pattern of asthma in rural children in the tropics represents a different type of asthma from that found in temperate zones. In contrast, the adult rural asthmatics and the urban children seemed to have the pattern of increased skin reactivity and serum IgE found in asthmatic patients from temperate climates.

Risk factors associated with the development of chronic lung disease in children

By better understanding the intrinsic and extrinsic factors that predispose children to chronic lung disease, strategies to prevent its development can be proposed. This article addresses conditions, such as bronchiolitis, croup, hyaline membrane disease, hydrocarbon ingestion, and near-drowning, that have been found to result in long-term changes in lung physiology. Also considered are the possible relationships of common respiratory infection, asthma, smoking, and air pollution to the development of chronic respiratory infection.

The chronic bronchitis complex in children

In childhood, a clear definition, etiology, natural history, therapy, and prognosis have not been described for chronic bronchitis. In fact, its validity as a single disease entity is in question. This article offers a pragmatic approach by considering "chronic bronchitis" as a pathophysiologic description of a symptom complex that results from the interaction of both intrinsic and extrinsic factors. In this schema, the physician should rule out more specific diagnoses and prevent further airway disease by limiting exogenous causes of airway damage and treating identifiable endogenous ones.

Community campaign against asthma

Asthma in children is common, underdiagnosed, and undertreated . We report a childhood asthma campaign in an inner city area, initiated by school doctors who then worked closely with family doctors. The campaign aimed to detect children with asthma, to institute or improve treatment, and to provide information about childhood asthma for families, teachers, school doctors, school nurses, and general practitioners. The symptoms and school attendance of most asthmatic children were reported by parents to have improved after the campaign, which was well received by both families and professionals. Similar campaigns focusing on other common childhood problems may provide concrete opportunities for collaboration between school health services and general practitioners and for improving children's health.

A prospective study of asthma in a rural community

Changes in symptoms and pulmonary function among asthmatic subjects in the general population remain poorly characterized. We studied 1,303 white residents aged seven years and older in Lebanon, Conn, a rural community largely unaffected by air pollution or major occupational exposures. These residents were examined in 1972 and again in 1978. There were 73 asthmatic subjects seen in 1972 who were followed. In addition, we identified 278 persons in 1972 who complained of wheezing who were also seen in 1978. Of the original asthmatic subjects, 50 (68 percent) were in remission; and from the original nonasthmatic population, 19 (1.4 percent) new asthmatic subjects were identified. Similarly, the condition of 215 (77 percent) of those who initially complained of wheeze had improved, whereas 56 (4.6 percent) of those initially studied either developed new wheeze or saw their wheezing worsen. When the groups of persons complaining of wheeze and the asthmatic subjects were analyzed for the presence of chronic bronchitis, we found a significant correlation between wheeze and chronic bronchitis in individuals aged 18 years and older (p less than 0.001) for both men and women, and a significant correlation (p less than 0.001) between asthma and chronic bronchitis in women aged 18 years and older. Loss of pulmonary function over time measured in terms of the forced expiratory volume in one second and the forced expiratory flow at 50 percent of total lung capacity was consistently greater for asthmatic adults than for nonasthmatic adults. Furthermore, when individuals were studied by the severity and duration of their asthmatic symptoms, a trend of worse pulmonary function was seen in those individuals with chronic asthma. We conclude that remission rates among asthmatic subjects and persons with wheeze are high in individuals aged seven years and older, that chronic bronchitis is frequently associated with wheezing and a history of asthma in adults, and that significant abnormalities in pulmonary function as well as accelerated loss of pulmonary function are associated with asthma.

A prospective study of the clinical manifestations of atopic disease in infancy

We prospectively followed a group of infants with a family history of atopy, from birth for up to 20 months of age. All infants were seen every 4 months and a history, physical examination and skin tests obtained. Atopic dermatitis and rhinitis occurred in about half the infants at some time during the study, while wheezing occurred in about a quarter. Both atopic dermatitis and rhinitis were more common in the first 12 months whereas wheezing occurred later and increased in prevalence with age. Defining atopy by the presence of atopic dermatitis or positive skin tests, only immediate food reactions were significantly associated with atopic infants. In contrast, rhinitis, a single episode of wheezing, colic, vomiting and delayed food reactions were not associated with atopy and thus are unlikely to be due to IgE-related mechanisms during infancy.

Prognostic factors predicting control of chronic asthma symptoms in children receiving prophylactic bronchodilator therapy

The factors predicting the control of asthma symptoms were studied in 312 consecutive children with chronic asthma who were receiving chronic prophylactic bronchodilator therapy. Asthma symptoms were controlled in 232 (74.4%) patients but not in 80 (25.6%) patients after 18 months of therapy. The cumulative percentage of patients in whom asthma symptoms were controlled increased with the duration of therapy. During the first 6 months of therapy, children who had a history of exacerbation of symptoms by fear stimulus or by dust had respectively an 83.3% (p = 0.0001) and a 35.4% (p = 0.003) lower rate of control of asthma symptoms than children without such a history. Similarly, children with a history of worsening asthma symptoms following ingestion of cold foods or drinks had a 71.4% (p = 0.002) lower rate of control of asthma symptoms after 6-12 months of therapy than children without such a history. Certain factors are important for predicting control of asthma symptoms at different times following the initiation of therapy and may relate to the lability of the airways to these stimuli.

Interferon--present and future prospects

The interferons are a group of proteins that have inspired a new era of investigation into biological modification. The interferons are now divided into subgroups characterized by chemical means and correspond to different biological responses which can be observed in terms of the inducer used, and the timing of the response. Identified originally as antiviral agents when homologous cell systems were treated prior to infection, new studies have extended these observations to place the interferons in a central role as a strong force in the regulation of immunologic responses. A marriage of interferonology and cell immunology is enlarging both our understanding of the action of these proteins and our ability to follow the course of an illness and eventually to control its outcome . Genetic engineering has provided a way to process quantities of interferon and provided the molecular sequence of all three classes of IFN including a model of the active site for IFN-alpha. The offshot of the technology developed to study the intracellular processes after interferon treatment have already led to increased sensitivity to detect virally treated diseases. Both the variety of the interferon inducers and the scope of parasites in which it can exert its influence provide a frontier of biological investigation which has at the root of its nature the very secret of life. In addition to cellular phenomena, the positive effects on tumor-bearing organisms and the ill effects on infant animals highlight the potential power of the interferons.

The structuring of an allergy index based on IgE-mediated skin sensitivity to common environmental allergens

We computed skin-test sensitivity levels in 485 adults puncture-tested with eight standardized, high-quality inhalant allergens tested at single concentrations. In order to quantitate the "average" IgE-mediated skin sensitivity of each subject, we used both nonparametric and parametric statistical methods to generate two "allergy indices" (Allergy Index I and Allergy Index II) based on sensitivity end-point data from the subpopulations of individuals positive to six of the eight allergens. For the 192 skin test-positive subjects, Allergy Index I and Allergy Index II were significantly correlated with each other (rs = 0.98, p less than 0.001) and with the number of positive skin-test reactions (rs congruent to 0.9, p less than 0.001) as well as with log[total serum IgE] (r congruent to 0.4, p less than 0.01). In 102 ragweed-positive subjects, log[specific IgE to ragweed] was significantly correlated with ragweed-specific "ragweed indices I and II" (r congruent to 0.6, p less than 0.01). Furthermore, the average daily symptom scores reported by 14 ragweed-positive subjects during the ragweed pollination season were significantly correlated with ragweed indices I and II (p less than 0.05). We propose the use of Allergy Index II in epidemiologic and genetic studies of allergic phenotypes as well as in clinical decisions for diagnosis and immunotherapeutic intervention.

Medical care of asthma and wheezing illness in children: a community survey

A survey was carried out to investigate the medical care of asthma and wheezing illness in a school population. Children with current wheezing illness were identified by a screening questionnaire to the parents of 5100 children in one school cohort from all schools in an outer London borough. Of the 89% who responded, 11.1% reported wheezing within the past 12 months. Parents of a sample of 284 wheezy children aged about 9 were interviewed at home about their child's illness and the related use of drugs and services. There was evidence of substantial underuse of services and this was not associated with social, family, or general practice factors. Considerable proportions of children were not having drug treatment, were receiving only non-antiasthmatic drugs, or were using antiasthmatic drugs incorrectly. The most important social and family factor associated with undertreatment was poor maternal mental health, and this factor appeared to explain the observed association of manual social class with undertreatment. Only about half of the most severe group were labelled as having "asthma," and those with this label were more likely to be receiving treatment and using outpatient services. The results show that the potential of modern treatment to prevent disability due to wheezing illness is not being realised despite the existence of a free and accessible health service.

Chest pain variant asthma

We present the cases of three patients who initially presented with chest pain but were ultimately diagnosed as having asthma. None had audible wheezing. A diagnosis of asthma was entertained and ultimately supported by a clinical response to bronchodilator therapy. Only one patient had significant but intermittent documentable reversible airway obstruction, while another had marked sensitivity to methacholine bronchial challenge. Two patients required short courses of oral corticosteroids before symptom ablation.

The usefulness of chest radiographs in first asthma attacks

To assess the value of routine chest radiography during acute first attacks of asthma, we studied 371 consecutive children over one year of age who presented with an initial episode of wheezing. Three hundred fifty children (94.3 per cent) had radiographic findings that were compatible with uncomplicated asthma and were considered negative. Twenty-one (5.7 per cent) had positive findings: atelectasis and pneumonia were noted in seven, segmental atelectasis in six, pneumonia in five, multiple areas of subsegmental atelectasis in two, and pneumomediastinum in one. The patients with positive films were more likely to have a respiratory rate above 60 or a pulse rate above 160 (P less than 0.001), localized rales or localized decreased breath sounds before treatment (P less than 0.01), and localized rales (P less than 0.005) and localized wheezing (P less than 0.02) after treatment; also, these patients were admitted to the hospital more often (P less than 0.001). Ninety-five per cent (20 of 21) of the children with positive films could be identified before treatment on the basis of a combination of tachypnea, tachycardia, fever, and localized rales or localized decreased breath sounds. Most first-time wheezers will not have positive radiographs; careful clinical evaluation should reveal which patients will have abnormal radiographs and will therefore benefit from the procedure.

Breast feeding, eczema, asthma, and hayfever

The association of breast feeding with rates of atopic illness during the first five years of life was assessed in a national study of 13 135 children studied during the first week and at age 5 years. Eczema was reported more often in children who had been breast fed; this relationship persisted even after allowance was made for social and family factors influencing the likelihood both of breast feeding and of eczema; the other factors most significantly associated with rates of eczema were parental history of eczema or asthma and advantaged family socioeconomic status. A similar, but less pronounced, positive association of breast feeding with reported hayfever became non-significant after adjustment for intervening factors. Rates of reported asthma were not influenced by breast feeding. "Any wheezing" including asthma was reported more often in children who had not been breast fed, but this association disappeared after adjustment for parental asthma and maternal smoking. Breast feeding does not appear to protect against these atopic diseases. The positive association with reported eczema might relate to accuracy of diagnosis or to associated influences not considered in the analysis; alternatively, it might be due to (recent) environmental contaminants crossing in breast milk, causing eczema in the child.

Underdiagnosis and undertreatment of asthma in childhood

A total of 179 Tyneside children who had suffered at least one episode of wheeze since school entry were seen at the age of 7. All but 14 had visited a doctor for chest symptoms, but a diagnosis of asthma had been offered to the parents of only 21 children, including three of the 56 children experiencing four to 12 wheezy episodes a year and 11 of the 31 children experiencing more than 12 episodes a year. Bronchodilator treatment was rarely offered in the absence of such a diagnosis, and two thirds of the children had never received a bronchodilator. Of the children experiencing four or more episodes a year, only a third had received bronchodilator drugs regularly, though half had lost more than 50 days from school because of wheeze. School absenteeism fell 10-fold in the 31 children finally offered continuous prophylactic treatment. Although many doctors had feared that use of the word "asthma" would cause anxiety, parents were uniformly relieved when given an explanation of their child's recurrent wheeze. This study uncovered a disturbing amount of ill health in children that was easily rectified. Probably this same problem exists in other areas.

Asthma and infant diet

The relationship of milk diet and solid feeding practices during the first 4 months of life to rates of early childhood asthma was studied prospectively in a birth cohort of 1110 children. The results of the analysis showed no significant association between rates of asthma and breast feeding or solid feeding practices. This was true for children both of asthmatic and non-asthmatic parentage. It is concluded that there is no evidence to indicate that early breast feeding had any detectable effect on the risk of subsequent asthma in this birth cohort. However, the possibility still remains that breast feeding may have a prophylactic effect for children from highly atopic families.

Prevalence of asthma and health service utilization of asthmatic children in an inner city

To determine the prevalence of asthma and to examine the pattern of health service utilization of asthmatic children in Baltimore, we sent questionnaires randomly to 4096 first and sixth graders attending Baltimore City public schools; 2898 completed the questionnaire. Asthma was defined as "a condition which causes difficulty in breathing, with wheezing noises in the chest." On the basis of this definition, we found that the cumulative prevalence of asthma was 10.5% and the 12 mo period prevalence was 7.2%. The prevalence was significantly higher for boys (male:female = 1.6:1) and for blacks (black:white = 1.5:1). Nearly 50% of the children with active asthma missed 6 days or more out of the school year because of illnesses due to asthma. Almost half the asthmatic children obtained their care of asthma in the emergency room, and twice as many blacks as whites used the emergency room as their primary source of care. Moreover, emergency room users had a higher school absentee rate than non-emergency room users.

An asthma rehabilitation program for families

The Family Asthma Rehabilitation Program of the Ontario Crippled Children's Centre is for children with severe asthma whose symptoms have not previously been well controlled. The severity of asthma symptoms on admission to the program was assessed for 75 children and the effects of the treatment were determined by means of severity ratings at time of discharge. Follow up interviews with families of children who graduated from the program between 1973 and 1978 suggest that the children remained well controlled, and parents were able to manage their children with minimized anxiety and stress. The issue of lack of continuity in the longterm care of the children was raised by many families: implications for the centre and for family physicians are considered.

Wheezing, asthma, and pulmonary dysfunction 10 years after infection with respiratory syncytial virus in infancy

Of the 180 children admitted to hospitals in Tyneside in the first year of life with proved respiratory syncytial virus lower respiratory tract infection, 130 were seen for review 10 years later and 34 of the remaining 50 children accounted for. Skin tests, lung function tests, and histamine-challenge and exercise tests for bronchial lability were undertaken in over 100 of the index children and a similar number of control children. A total of 55 (42%) of the 130 index children had had further episodes of wheeze, while only 21 (19%) out of 111 controls had ever wheezed; but few (6.2% v 4.5%) had troublesome symptoms at the age of 10. There was a threefold increase in the incidence of bronchial lability in the index children but no excess of atopy. Maximum expiratory air flow was reduced throughout the vital capacity manoeuvre in the index children, even when those with a history of recurrent wheeze were excluded. Results of single-breath nitrogen washout tests were normal, however, suggesting that ventilation was not appreciably uneven, even though expiratory flow was restricted. These differences might have been caused by infection damaging the growing lung but might also be explained by pre-existing differences in the airway, rendering certain children more susceptible to symptomatic infection when first challenged by the virus in infancy.

Respiratory infections in the first year of life in children at risk of developing atopy

Ninety-two infants, each of whom had one parent with asthma or hay fever, were followed up from birth to age of 1 year and 72 to the age of three years. During the first year of life respiratory symptoms, eczema, and respiratory viral infections were all reported. Within the first year 24 babies developed eczema; 28 had a wheal of 1 mm in diameter or more on prick skin testing with cutaneous allergens. Forty-three children had one or both of these characteristics and formed an atopic subgroup; by the same criteria, 49 children were non-atopic. The number of respiratory infections in the two groups was not significantly different; similar viruses were isolated from both groups. These viruses were associated with both upper and lower respiratory tract infections. Wheezing was a clinical feature in 12 children during lower respiratory tract infections. Of these babies six were atopic in the first year of life. Of the six non-atopic babies, one had eczema in the second year and five children developed raised total serum IgE values within the 3 years.

Asthma from childhood at age 21: the patient and his disease

Information was obtained from 336 21-year-olds who had begun wheezing before the age of 7 about their knowledge of asthma and its effect on their current life style. Two-thirds of the subjects were still symptomatic. A control group of 62 subjects was available for comparison. Knowledge about asthma was poor, particularly among those with less troublesome symptoms. Half of those with frequent episodic asthma and one-third with persistent asthma did not regard excess use of bronchodilator aerosols as potentially dangerous. Over three-quarters of those with persistent asthma were not receiving adequate treatment. One-third of third of those with persistent asthma were missing substantial time from work because of respiratory illness, and a similar proportion were restricting sporting activities. The incidence of smoking was disturbingly high in all asthma groups. The higher the number of cigarettes ever smoked and the higher the current tobacco consumption the less satisfactory was the progress of asthma. Both cigarette smoking and severity of asthma contributed to chronic production of sputum. Children and teenagers with asthma should be educated to seek more appropriate medical help and thereby reduce morbidity.

Natural history of allergy in asthmatic children followed to adult life

This is a prospective study of wheezing children, who were followed up from the ages of seven to 21 years. Allergy factors were documented in all subjects. Hay fever and positive reactions to skin allergy tests were more prevalent in 21-year-old subjects with severe asthma. However, 50% of subjects who had ceased wheezing has hay fever, and 65% had at least one positive skin test reaction. The number of asthmatic subjects with hay fever and positive skin test reactions progressively increased between the ages of seven and 21 years. Eczema was significantly associated only with severe asthma. More 21-year-old subjects with severe asthma wee breast-fed in infancy for longer periods than in the control group and in groups with mild to moderate asthma. Further investigation is needed before the hypothesis that breast feeding protects against the development of allergic phenomena can be accepted.

Variability of airways hyper-reactivity and allergy in cystic fibrosis

The importance of bronchial hyper-reactivity and allergy, and treatment with bronchodilators and corticosteroids, in the management of patients with cystic fibrosis is poorly understood. Three tests generally regarded as useful in the diagnosis of asthma were evaluated in 25 children with cystic fibrosis. The constancy of a child's response was assessed by histamine bronchial provocation, exercise challenge, and tests of skin allergy during a 6-month period. Although a positive response to these tests was related to impaired pulmonary function, 44% of children had variable responses to histamine, 56% to exercise, and 24% to skin tests which were unrelated to exacerbations of chest infection or to changes in pulmonary function. These results show the complex nature of airways hyper-reactivity and allergy in cystic fibrosis, and suggest that 'anti-asthma' therapy is not justified solely on the basis of one positive response to these tests.

The incidence and causative factors of atopic asthma and rhinitis in an Orkney farming community

Fifty farming families on the mainland (the largest island) or Orkney were surveyed to assess the amount of allergic respiratory disease and the principal causative factor. This account deals with only type I allergy and demonstrates a prevalence of asthma and rhinitis of 17.3% and of extrinsic asthma and rhinitis, in which definite allergic causes can be identified, of 12.7%. In addition it is shown that over one-fifth of the farming community are 'atopic' in that they demonstrate positive prick tests to one or more allergens. Less than 50% of those with allergic respiratory disease have attended the doctor with their complaint, a fact which calls in question the validity of epidemiological studies of allergic disease based on hospital and clinic attendances. Sex distribution confirms the finding that males suffer from asthma more frequently than females, however more females than males give positive skin tests without exhibiting symptoms of allergy. Pollens, animal danders and fungi all have a part to play in the aetiology of asthma and rhinitis among Orkney farmers, although the incidence of grass pollenosis is well below average. The two commonest allergens are hay dust and Dermatophagoides pteronyssinus which are found frequently to affect the same subject.

Exercise-induced asthma in Nepalese children

Three hundred and one children between 5 and 15 years old in the hills of east Nepal were studied to determine the prevalence and the main causes of asthma and atopy. Asthma was diagnosed on the basis of history, clinical examination and the results of a 6-min exercise test (step test). Asthma was diagnosed in six children, none of whom was skin prick test positive. We present here normal values of baseline peak expiratory flow rate (PEFR), and the exercise-induced changes in PEFR in normals, asthmatics, other wheezy children and others with atopic histories. The results of the skin prick tests are presented with the atopic histories in another paper.

Physical Activity and the Asthmatic

In brief: Recent studies suggest that avoiding exercise is unwarranted and detrimental for asthmatics. Although exercise provokes bronchospasm in most asthmatics, the severity of exercise-induced asthma can be reduced by several factors: control of exercise duration; less intense, intermittent exercise; warm-ups; warmer, humid inspired air; aerobic fitness; and drugs. Regular vigorous activity increases fitness, enhances tolerance to attacks, and provides more social and psychological independence. The recent development of protective medications has made such activity possible for many asthmatics. Preexercise cromolyn sodium and beta adrenergic agonists are recommended for blocking or reversing attacks.

A genetic-epidemiologic study of human immune responsiveness to allergens in an industrial population: I. Epidemiology of reported allergy and skin-test positivity

Four hundred six subjects, comprising a 10% random sample of all employees, and a sample of "self-reported" allergic employees of a light industrial plant participated in an epidemiologic study of allergy. Puncture skin testing with a wide variety of crude allergens revealed a significantly higher prevalence of IgE-mediated sensitivity in males than females (29% males and 7% females in a random group; 60% males and 30% females in a self-reported allergic group); however, reported prevalence rates for "allergy" and different allergic symptoms were generally not different between males and females. Interestingly, reported asthma was greater in skin-test-positive subjects than in skin-test-negative subjects. We also noted a decrease in skin-test positivity with increasing age in self-reported allergic subjects. This was significant in the case of several crude allergens but not in the case of positivity to at least one allergen. We also found evidence that people born in and who have been resident in "Zone I) (MD, PA, Del, NJ, or DC) for most of their lives exhibit a greater prevalence of skin-test positivity than people who were born in and have lived for much of their lives in the northeastern United States (east of the Mississippi River and to the north of South Carolina) other than in Zone I.

Prevalence of asthma in Rhodesian Africans

The prevalence of asthma in a small African town has been assessed using two questionnaires. The first was put to 9768 subjects aged 5 years and older and the second, more detailed, questionnaire to random selections of these subjects grouped according to their replies. The overall prevalence of asthma was 1.40%. In those under 20 years of age it was 1.20% and in adults, 1.57%. This adult rate is similar to those in developed countries but that in children is lower. The relative paucity of childhood asthma is compatible with the suggestion that infestation with parasites may protect against the disease.

Genetic factors in childhood asthma

The prevalences of asthma and atopy were examined in the families of 77 asthmatic and 87 control children attending a London general practice. The prevalence of asthma in first degree relatives of asthmatic children was found to be significantly higher than in relatives of control children, and this difference was more pronounced for relatives of atopic probands than for relatives of non-atopic probands. Among the relatives of asthmatics, atopic asthma was more common than non-atopic asthma, irrespective of the atopic status of the proband. However, among the relatives of control children, neither the prevalence of asthma nor the atopic status of the asthmatic relatives was influenced by the atopic status of the proband. These findings support the hypothesis that asthma and atopy are inherited independently. Although atopy itself does not predispose to asthma, it may enhance a genetic susceptibility to the condition, thus increasing the likelihood that the latter will be expressed.

The natural history of childhood asthma to adult life

A randomly selected group of 331 children who had started to wheeze in childhood and a control group of 77 children were prospectively studied clinically and physiologically from 7 to 21 years of age. Most subjects improved during adolescence and about 55% of those whose wheezing had started before 7 years and stopped before adolescence remained wheeze free. Forty-five per cent of subjects who had apparently ceased to wheeze at 14 years had minor recurrences of wheezing between 14 and 21 years of age. Fewer than 20% of those with persistent symptoms in childhood had become totally wheeze free during adolescence, although there was amelioration in symptoms. Girls did less well during adolescence than boys, so that there was no longer an increased preponderance of boys with increasing severity of asthma. Normal growth was achieved in all grades despite the persistence of symptoms in many cases. At 21 years of age features of airways obstruction were often found during an interval phase, especially in those who had more persistent symptoms.

A family study of the genetic basis of asthma and wheezy bronchitis

The family histories relating to asthma and wheezy bronchitis were examined in 77 asthmatic, 78 wheezy bronchitic, and 87 control children, aged between 1 and 12 years. The percentage of children with at least one asthmatic relative was significantly greater in the asthmatic and wheezy bronchitic probands than in the controls; and asthma was more prevalent in the relatives of both groups of wheezy probands than in the relatives of controls. Similarly, the percentage of children with at least one wheezy bronchitic relative tended to be greater in asthmatic and wheezy bronchitic probands than in the controls; and wheezy bronchitis tended to be more prevalent in the relatives of both groups of wheezy probands than in the relatives of controls. However these differences did not reach significance. The strong similarities between asthmatic and wheezy bronchitic children in their family histories of asthma and wheezy bronchitis suggest that these two forms of wheezy illness share a common genetic defect.

Efficacy of orally administered salbutamol and theophylline in pre-schoolchildren with asthma

Oral administration of salbutamol and theophylline has been shown to be effective in relieving bronchoconstriction in asthmatic children aged between 3 and 5 years. Changes in respiratory function were monitored using a Wright's low range peak flow meter and a modification of the forced oscillation technique. A combination of both drugs in half doses was as effective as either alone. Nebulised salbutamol produced considerable further improvement in lung function.