Objective: To investigate the association of non-bacterial respiratory pathogens with asthmatic diseases in children, and the clinical significance of total serum IgE levels and peripheral eosinophil count in infection with non-bacterial respiratory pathogens.
Methods: Indirect immunofluorescence assay was used to detect IgM antibodies against nine types of non-bacterial respiratory pathogens in the sera of 490 children with asthmatic diseases between September 2010 and September 2011. Pathogens were analyzed and total serum IgE levels and peripheral eosinophil count were measured in IgM-positive cases.
Results: Of the 490 children with asthmatic diseases, 47.6% (233 cases) were positive with IgM antibodies against non-bacterial respiratory pathogens, the most common being Mycoplasma pneumoniae (MP) (25.3%), followed by adenovirus (ADV) (8.9%) and influenza B virus (Flu B) (8.8%). Thirty-six cases suffered from co-infection of two or more non-bacterial pathogens, mainly comprising MP and other pathogens (94%). There were significant differences in the total detection rate of IgM antibodies among all age groups (0-30 days: 50.0%; 1-6 months: 67.3%; 0.5-1 year: 33.1%; 1-3 years: 57.3%; 3-8.9 years: 61.7%). The positive rate of IgM antibodies against respiratory pathogens was highest in children with bronchial asthma, followed by children with asthmatic bronchitis, and it was lowest in children with bronchiolitis. IgM-positive children had significantly decreased blood eosinophils and significantly increased total serum IgE levels.
Conclusions: The main non-bacterial respiratory pathogens include MP, ADV and Flu B in children with asthmatic diseases, and co-infection of MP and other non-bacterial pathogens is common. Infants aged 1 to 6 months have a higher infection rate than other age groups. Monitoring the changes in total serum IgE levels and peripheral eosinophil count has great significance for the clinical diagnosis and treatment of asthmatic diseases in children.