TOPLINE

Among children aged 0-3 years, rhinovirus infections, particularly rhinovirus C infection, and the detection of common pathogenic bacteria were associated with longer asthma-like episodes. Rhinovirus C infection and younger age were also associated with higher odds of severe asthma exacerbations.

METHODOLOGY

• Using data from a prospective Danish population-based cohort, researchers examined whether specific microbial triggers were associated with the duration and severity of asthma-like episodes in young children.
• They analysed 453 nasopharyngeal samples collected during asthma-like episodes from 268 children aged 0-3 years. Asthma-like episodes were defined as cough, wheeze, and/or breathlessness lasting 3 or more days, with at least 3 symptom-free days between them.
• Nasopharyngeal samples were tested for respiratory viruses using polymerase chain reaction and for bacteria using standard culture methods, and parents recorded symptoms in daily diaries from birth to 3 years of age.
• The researchers evaluated the duration of episodes and the likelihood of progression to severe asthma exacerbations requiring treatment with oral prednisolone or high-dose inhaled corticosteroids and/or hospital admission.
• Additional exploratory analyses assessed age-related effects, pathogen-pathogen interactions, and interactions between microbial triggers and selected asthma risk loci.

TAKEAWAY

• After adjustment for age, rhinovirus infection was associated with a 27% longer duration of asthma-like episodes compared with episodes without rhinovirus (P = .012), with rhinovirus C infection associated with a 50% longer episode duration (P = .034).
• Rhinovirus was associated with more than twice the odds of a severe asthma exacerbation (odds ratio [OR], 2.26; P = .027), and rhinovirus C was associated with more than fourfold higher odds (OR, 4.38; P = .002).
• The detection of Streptococcus pneumoniae, Haemophilus influenzae, and/or Moraxella catarrhalis was associated with 61% longer episodes compared with episodes without these bacteria, and M catarrhalis alone was linked to a 47% longer duration (P < .001 for both). In contrast, respiratory syncytial virus and parainfluenza and influenza viruses were associated with 25%-33% shorter episodes (P < .05 for all).
• Younger age was associated with an 18% longer duration of asthma-like episodes per 1-year decrease in age (P = .031) and with higher odds of a severe asthma exacerbation (OR, 1.71; P = .020).

IN PRACTICE

"[The study] findings suggest that specifically targeting rhinovirus C and M catarrhalis could lead to better management and possibly prevention of longer and/or more severe wheezing episodes in young children," the authors of the study wrote.

SOURCE

The study was led by Julie Nyholm Kyvsgaard, Copenhagen Prospective Studies on Asthma in Childhood, Copenhagen University Hospital - Herlev-Gentofte, Copenhagen, Denmark. It was published online on October 06, 2026, in Pediatric Allergy and Immunology.

LIMITATIONS

The study lacked a healthy control group, and each pathogen was compared with episodes lacking that pathogen, not with episodes free of any pathogen. Samples were not collected from every asthma-like episode, which may have biased the sample towards more severe cases. Bacteria were identified using culture alone, so only selected species were detected, and their levels were not measured.

DISCLOSURES

The study was funded by Fabrikant Vilhelm Pedersen og Hustrus Legat. One author reported receiving a speaking fee from a pharmaceutical company.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.