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This cross-sectional emergency department study of 70 wheezing children and 59 control subjects (2 mo to 16 yr of age) examined the prevalence of respiratory viruses and their relationship to age, atopic status, and eosinophil markers. Nasal washes were cultured for respiratory viruses, assayed for respiratory syncytial virus (RSV) antigen, and tested for coronavirus and rhinovirus RNA using reverse transcription-PCR (RT-PCR). Also evaluated were eosinophil numbers and eosinophil cationic protein (ECP) in both nasal washes and serum, along with total IgE and specific IgE antibody in serum. Respiratory viruses were detected in 82% (18 of 22) of wheezing infants younger than 2 yr of age and in 83% (40 of 48) of older wheezing children. The predominant pathogens were RSV in infants (detected in 68% of wheezing subjects) and rhinovirus in older wheezing children (71%), and both were strongly associated with wheezing (p < 0.005). RSV was largely limited to wheezing children younger than 24 mo of age, but rhinovirus was detected by RT-PCR in 41% of all infants and in 35% of nonwheezing control subjects older than 2 yr of age. After 2 yr of age the strongest odds for wheezing were observed among those who had a positive RT-PCR test for rhinovirus together with a positive serum radioallergosorbent testing (RAST), nasal eosinophilia, or elevated nasal ECP (odds ratios = 17, 21, and 25, respectively). Results from this study demonstrate that a large majority of emergent wheezing illnesses during childhood (2 to 16 yr of age) can be linked to infection with rhinovirus, and that these wheezing attacks are most likely in those who have rhinovirus together with evidence of atopy or eosinophilic airway inflammation.

Asthma in children and young adults is strongly associated with immediate hypersensitivity to indoor allergens, notably those derived from the house dust mite. In addition, outdoor air pollution is considered to aggravate existing asthma. We investigated the prevalence of asthma and the pattern of allergen sensitization in a mite-free environment with low levels of outdoor air pollution. A total of 567 children aged between 12 and 14 attending Los Alamos Middle School, NM (altitude 7,200 feet) were screened using a respiratory questionnaire; 120 children (53 control children) underwent allergen skin testing and serum IgE measurement, and their bronchial reactivity to histamine was measured. Dust was collected from 111 homes and the level of indoor mite and cat allergen measured. The prevalence of respiratory symptoms was high (13%), and from the detailed testing it was estimated that 6.3% of the children had asthma (defined as symptomatic bronchial reactivity). Children with asthma had elevated IgE, 367 (179 to 755) versus 38 (23 to 61), and predominant sensitization to cat, 68 versus 20% (p < 0.001). A high number of households (77%) had a pet cat or dog. The concentration of mite allergen was very low (mean 0.18 micrograms Der p milligrams sieved house dust), whereas that of cat allergen was high in homes with a cat (80.8 micrograms Fel d milligrams) but also in homes with no cat (3.2 micrograms Fel d milligrams). The results show that in a mite-free environment with low levels of outdoor air pollution, asthma was still a major cause of morbidity among schoolchildren.(ABSTRACT TRUNCATED AT 250 WORDS)