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Cough is a common and troublesome symptom in people with asthma and is often associated with poorer asthma control and exacerbations. Apart from asthma, other causes or comorbidities might underlie cough in asthma, such as rhinosinusitis and bronchiectasis. Eosinophilic inflammation and bronchoconstriction can lead to an acute episode of cough or worsen chronic cough. Cough hypersensitivity with laryngeal paraesthesia, allotussia, and hypertussia might underlie the cough of asthma through augmented sensory nerve excitability of upper-airway vagal sensory nerves. Cough associated with bronchoconstriction and type 2 inflammation should respond to inhaled corticosteroids and long-acting β-adrenoceptor agonist therapy. For cough hypersensitivity in adults, speech and language therapy and neuromodulators (eg, gabapentin) could be considered. In children, there is no consistent association of asthma with cough sensitivity or between cough and asthma severity. Further research is needed to realise the potential of cough as a measure of asthma control, to understand the mechanisms of cough in asthma, and to develop safe, effective treatments and a precision-medicine approach to the management of cough in asthma in children and adults. [ABSTRACT FROM AUTHOR]

The epidemiological studies cited have indicated that viruses are commonly associated with wheezing illnesses in populations, in individuals, and in time, but, unlike bacteria, are rarely found during asymptomatic periods. Viruses have been identified in up to 50% of wheezing illnesses and asthma exacerbations occurring in childhood, and in up to 20% of those in adults. In childhood the predominant organisms identified have been rhino-viruses, RSV and parainfluenza viruses, but corona-viruses have not been studied adequately. Wheezing appears to be more common during rhinovirus and RSV than other virus infections in children spontaneously presenting with respiratory infections to medical care, but all virus groups have been incriminated, and in general, wheezing occurs in upwards of 50%) of viral infections in asthmatics followed prospectively. The few adult studies available show little difference between viruses in identification rates during wheezing, or propensity to result in wheezing. The predominant viruses change with age, and children with asthma seem to be more prone to symptomatic virus infections than other children, although the presence of atopy alone does not appear to be important. There are important gaps in our knowledge of the epidemiology of virus-associated wheezing attacks, and further prospective studies are required, using early investigation and sensitive methods for identifying rhino-viruses and corona-viruses, to study severe asthma in children and adults. It is hoped that the use of nucleic acid hybridization and newer antigen-detection techniques will improve the ability to identify difficult viruses such as corona-viruses and rhino-viruses in the future. The ability to identify subclinical infections and compare the ratio of subclinical to clinical infections in normal and asthmatic children would be useful but would require intense monitoring of both groups for an extended period (minimum 12 months to cover seasonal variation) with full virological studies every 2-4 weeks-a difficult and expensive task. Another important line of study would be to prospectively document indoor aeroallergen exposure and virus infections in the same individuals, and compare their importance as precipitants of acute severe asthma attacks. With a clearer understanding of the groups at risk for asthma attacks, and the factors which put them at risk and precipitate their attacks, effective preventive strategies will become more feasible. [ABSTRACT FROM AUTHOR]

The article provides information on various studies on the role of bronchoscopy as a research tool in asthma. One of the studies discussed the role of the mast cell in asthma, and underlined the fact that raised levels of histamine are found in lavage specimens taken during the early asthmatic response, but not the late response, suggesting that mast cells--the principal source of histamine--do not play an important role in the late asthmatic response. Another study posed the fundamental question of what leads to the predisposition to asthma in those subjects who then develop symptoms when exposed to allergen. A separate research underlined the fact that biopsies and lavage yield different information, with lavage just looking at cells and mediators within the lumen, while biopsies can examine the epithelium, the basement membrane, the lamina propria, nerves and vessels.

The article provides information on studies focused mainly on the epidemiology of asthma and bronchial hyperresponsiveness. One of the studies presented evidence that a previously unreported fourfold rise of asthma mortality in the 5-34 year age group had occurred in New Zealand in the 1940's and 1950's, although the peak mortality and the rate of climb were lower than in the well-documented "epidemics" in the 1960's and late 1970's. Another study associated higher standards of living and urbanization with an increased prevalence of reversible airways obstruction in African children. A study reported that from surveys of primary school children in 1985 and 1988 in Nottingham, there was a 50% rise in diagnosed asthma while rates of wheezing ever, wheeze in the last year and asthma medication use remained relatively stable, after adjusting for age and sex.

The article provides information on several studies studying the methodology of bronchial challenge testing. One of the studies stemmed from the observation that a Wright nebulizer chamber gets colder during use. It was shown that there was a gradual fall in output from the nebulizer during use, and that this correlated very closely with the fall in temperature already observed. Another research studied histamine tachyphylaxis in asthmatics, relating it to bronchial hyperreactivity. A separate study presented interesting data suggesting that the mechanism of action of leukotriene (LT)E4 in asthmatics is likely to be very different from the mechanisms of LTD4 and C4, with which it was previously grouped as show releasing substance of anaphylaxis.

The article provides information on several studies related to asthma. There has been recent work suggesting that inhaled fenoterol may be associated with asthma deaths. Also a separate study described the results of a study which assessed the selenium status of asthmatic patients in New Zealand. A group of researchers showed that, in a group of asthmatics maintained for 12 months on inhaled corticosteroids, after cessation of therapy the first suggestion of deterioration of airway function was from the recurrence of asthmatic symptoms some 3 months after therapy was stopped.