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The source document for this Digest states:
Respiratory disease is the most common cause of mortality in children in underdeveloped economies and the commonest cause of morbidity in developed economies. Respiratory tract symptoms are particularly prevalent in young children and evidence for the relative contributions of potentially remediable environmental factors is emerging. The state of children’s respiratory health is determined by the interaction of many factors including potential stressors from their environment, patterns of exposure, individual vulnerability and genetics. Identifiable risk factors include infection, air pollution (indoors and outdoors), diet, lifestyle, social condition, occupation, and provision of medical care. They produce a multi-causal effect that has both short- and longer-term manifestations with implications for lifelong respiratory health. This effect varies with gender, developmental age and ethnicity.
This report provides a succint overview of the current state of knowledge with regard to the influence of the environment on the respiratory health of children, comprising the whole array of disorders and symptoms affecting the respiratory tract ranging from rhinitis and upper respiratory tract infections to asthma and pneumonia. The target population covers the period from fetus to young adult (up to 18 years of age) in order to reflect the whole range of age-specific conditions and unique periods of vulnerability dependent on growth and development. It aims to identify the gaps in knowledge and highlight the areas where policy action at Community level would have a significant impact on improving respiratory health in the EU.
Context
Figure 1: causes of death in children in Africa and South East AsiaChildhood respiratory illness is the commonest cause of morbidity in industrialised countries and, acute respiratory infections (ARI) are common causes of death and serious morbidity in young children in underdeveloped and emerging economies (Figure 1). Serious morbidity is less and the causative infective agents differ in developed economies such as those in the EU in that bacterial infections, including tuberculosis, are common in underdeveloped countries while viral infections explain most ARI in developed economies. In temperate European countries there is a marked seasonality of ARI with a significant rise in prevalence in the winter months falling to relatively low levels in the summer.
Figure 2: Reports of respiratory syncitial virus (RSV) isolates 1995-2000This pattern is evident for the respiratory syncytial virus (RSV) which is the commonest cause of the viral pneumonia labelled as “bronchiolitis” and which predominantly affects infants and very young children (Figure 2). Whereas serious morbidity and mortality from respiratory disease has fallen to low levels in developed economies, the total burden of respiratory disease remains high with a shift from life threatening ARI to an increased incidence of asthma and related atopic disease (rhinitis/hayfever and eczema).
The reasons for what has been termed the “asthma and atopy epidemic” are not yet entirely clear although several environmental risk factors have been proposed including a reduction in the overall burden of infectious disease – the so-called hygiene hypothesis [Strachan, 1989], dietary factors including low anti-oxidant intake [Seaton et al 1994; Fogarty & Britton 2000] and greater intake of processed fats [Helms 2001].
Whereas in the last decade increased exposure to allergens and particularly those within the internal environment, including the house dust mite, were considered to be major factors, more recent data do not support this association [Custovic et al 1998; Gotzsche et al 1998]. Prospective birth cohort studies are currently in progress in order to clarify the relative contribution of the putative risk factors [Lau et al 2000; Burrows et al 1995] and some of the major European cohorts are identified in chapter 5).
Source & ©: EU 
The source document for this Digest states:
Temporal changes
Figure 3a: Total workload in Scottish.The marked reduction in the prevalence of life threatening ARI in developed countries in the last 50 years reflects an improved standard of living, immunisation against tuberculosis, pertussis, diphtheria, measles and Haemophilus influenzae and the introduction of effective antimicrobial drugs and the relatively low rate of HIV infection. For those children with life threatening disease technological advances in managing respiratory failure have also had their impact clearly identified.
Figure 3b: Respiratory Disease workload per 1000 patients.Targets for further reductions in the burden of illness particularly in the youngest age groups include the elimination of RSV infection by an effective vaccine and a reduction in exposure to cigarette smoke in utero and in early childhood. Whereas the hospital work load for acute respiratory events including asthma may be diminishing the burden in primary care remains at high levels with the highest workload in the youngest age groups (Figures 3a, 3b).
Although sudden infant death syndrome (SIDS) is of unknown aetiology sufficient is known of its epidemiology for some practical preventive measures to have been formulated. The incidence rate in the UK increased from the 1950s (c1.6 per 1000 live births) to the 1980s (c2.5/1000) and thereafter declined to c0.65/1000 in 1996 with stability or a very slow further decline since. It is likely that this recent decline is related to a response to recommendations that infants should sleep in the supine position, since prone sleeping had been observed to be a risk. The observation in monitored infants that death or near-death is preceded by a period of severe bradycardia speaks for such factors being mediated via the autonomic nervous system and its central connections.
Impact on Therapy
In developed economies improvements in therapeutic options including age appropriate inhalation delivery devices, antibiotics and organisation of care have resulted in increasing actuarial survival for conditions that in previous generations and epochs were invariably fatal in childhood. This increased survival applies to a number of conditions including cystic fibrosis, unusual congenital anomalies such as congenital diaphragmatic hernia and respiratory complications of other conditions such as extreme prematurity and neuro-muscular disorders. In cystic fibrosis, for example, a strong cohort effect on actuarial survival, although modulated by socio-economic factors, has become apparent since the disease was first characterised in the 1940s [Britton 1989]. The increased survival of children with significant lung disease, or with neuro-muscular disorders and associated respiratory impairment, is producing a growing number of young adults with increased susceptibilities to environmental hazards.
Source & ©: EU
The source document for this Digest states:
Geographical variation
There are important differences in the prevalence of childhood respiratory diseases in different European countries; as a generalization, there is more asthma and allergy in the prosperous west and more infective disease in the poorer East. There are also North- South differences in the prevalence of asthma and allergies. These speak for important and perhaps correctable environmental factors either in their causation or in their triggering. The diseases of greatest interest affecting the child’s respiratory system in a European context are pneumonia, viral bronchiolitis, measles, tuberculosis, HIV infection, sudden infant death syndrome (SIDS), cystic fibrosis and asthma/allergies. With the exception of SIDS, these fall into two categories, primarily infectious and primarily genetic diseases.
Source & ©: EU
Definitions
Definitions of childhood respiratory disease also need to be considered as they can distort what appear to be important regional differences in disease expression. In this regard childhood bronchitis and asthma are good examples. Asthma has been defined as intermittent episodes of airway obstruction that either results spontaneously or responds to treatment. This definition separates it from chronic progressive obstructive lung disease typically seen in middle to late adult life and which is less responsive to therapy. However, the term “bronchitis” is more widely used in Central and Eastern Europe than in Northern and Western European countries. The description “bronchitis” relates to a population of children with chronic cough and sputum production that can also be features of asthma. Whether these differences are entirely explained by differences in diagnostic fashion or to real differences in host susceptibility and environmental exposures is unclear. However, differences in the prevalence of these two conditions in East and West Germany and associated differences in the expression of atopy before unification suggest that these differences are real and that they have an underlying environmental explanation. [Von Mutius et al., 1992].
Source & ©: EU
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