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Increased incidence of asthma and pulmonary dysfunction after severe lower respiratory tract infection in infancy
Insights
Childhood lower respiratory tract infections, particularly viral ones, significantly increase asthma risk. Early infancy infections heighten this risk, even without a family history of allergies.
Area of Science:
- Pediatric Pulmonology
- Epidemiology
- Infectious Diseases
Background:
- Lower respiratory tract infections (LRTIs) in infancy are common.
- The long-term impact of LRTIs on childhood pulmonary health and asthma development is not fully understood.
Purpose of the Study:
- To investigate the association between childhood lower respiratory tract infections and the subsequent development of asthma and pulmonary function abnormalities.
- To identify risk factors for asthma development post-infancy LRTIs.
Main Methods:
- A longitudinal study followed 35 children with a history of infantile pneumonia for 5-10 years.
- Methods included questionnaires, physical examinations, pulmonary function tests (PFTs) with bronchodilators and hypertonic saline challenges, and methacholine challenge tests.
- Risk factors such as family history of allergies and wheezing were assessed.
Main Results:
- 37% of children with infantile pneumonia developed asthma, a significantly higher rate than the general population.
- Abnormalities were observed in various pulmonary function parameters including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and mid-expiratory flow rate (FEF25-75%).
- Asthmatic children showed significantly reduced methacholine challenge test thresholds (PC20 < 5 mg/ml). Family allergy and wheezing were significant risk factors, but asthma incidence was also elevated in children without a family history of allergies.
Conclusions:
- Infantile lower respiratory tract infections, especially viral infections, are strongly associated with an increased risk of childhood asthma.
- Genetic predisposition plays a role, but viral infections in early infancy appear to be a critical factor in asthma development, independent of family allergy history.
- These findings highlight the importance of preventing and managing early childhood respiratory infections to mitigate long-term pulmonary health consequences.
Abstract:
In the present study we tried to define the effect of lower respiratory tract infections upon pulmonary function and/or asthma in childhood. Thirty-five children with history of pneumonia in infancy were followed five to ten years later; all were asked to respond questionnaire, received physical examination and were diagnosed for pulmonary function. The results follow: 13 children (37%) had developed asthma, a significantly higher percentage than normal prevalence among students in this area. Simple pulmonary function test, pulmonary function test after distilled water mist and after hypertonic saline (4.5%) mist all showed abnormal values in VC (17%, 14%, 29% respectively), in IVC (46%, 51%, 53%), in FVC (20%, 23%, 24%), in FEVl (17%, 23%, 29%), in FEF25-75% (37%, 49%, 47%), in FEF75% (26%, 23%, 29%) and in FEVl/VC (20%, 14%, 29%). Methacholine challenge test (PC20) showed a marked decrease of PC20 in asthmatic children; each was less than 5 mg/ml (mean value; 0.99 mg/ml). Family-allergy in at least one parent and wheeze were the two significant risk factors. Nevertheless, in 22 non-family-allergy children, the occurrence of asthma was also higher than general prevalence (18.2% vs 5.6%). Wheezing was evident in viral infections in infancy, but bacterial culture from sputum or throat swabs failed to find pathogenic bacteria. These results indicate that while the genetic factor may be important, viral infections may be more important because, even in non-family-allergy children, the occurrence of asthma was higher for infants infected in early infancy than the general prevalence for age-matched students.