Epidemiology of multiple respiratory viruses in childcare attendees

Abstract

Background: The identification of multiple viruses during respiratory illness is increasing with advances in rapid molecular testing; however, the epidemiology of respiratory viral coinfections is not well known.

Methods: In total, 225 childcare attendees were prospectively followed for up to 2 years. Nasal swabs were collected at respiratory illness onset and every 7-10 days until illness resolution. Swabs were tested by polymerase chain reaction for 15 respiratory viruses and subtypes.

Results: At least 1 virus was detected in 382 (84%) of 455 new-onset illnesses with multiple viruses identified in 212 (46%). The proportion of subject swabs with multiple viruses detected changed as respiratory illnesses progressed from week to week, as did the prevalence of individual viruses. Children with multiple viruses detected at the time of illness onset had less frequent fever (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.35, 0.90), however, these children more often had illness symptoms lasting over 7 days (OR, 1.94; 95% CI, 1.20, 3.14).

Conclusions: A high proportion of daycare attendees had multiple viruses detected during respiratory illnesses. Delay between onset of illness and viral detection varied by virus, indicating that some viruses may be underrepresented in studies of virus epidemiology that rely on only a single test at symptom onset.

Figure 1.

Correlations between the presence and quantity of 15 viruses and subtypes detected in 823 swabs from children with mild to moderate respiratory illness. Red scale: Synergistic virus combinations that occur more frequently or at higher viral loads when together. Blue scale: Antagonistic virus combinations that occur less frequently or with inversely correlated viral loads when together. Strength of color represents magnitude of positive (red) or negative (blue) correlation coefficient. Note that data are mirrored across the diagonal. Abbreviations: AdV, adenovirus; Flu, influenza; HBoV, human bocavirus; HCoV, human coronavirus; HMPV, human metapneumovirus; HRV, rhinovirus; MVI, multiple virus illness; PIV, parainfluenza; RSV, respiratory syncytial virus; SVI, single virus illness.

Figure 2.

Distribution of virus detections at illness onset and 3 subsequent weekly swabs (weeks 1–3). Pie charts indicate the no. of viruses detected at illness onset and at 3 subsequent weekly follow-up swabs. Distributions are represented overall and by incident detection (first detection of the virus during the illness) and by persistent detection (repeated detection of that virus during the illness). Bar graphs indicate overall no. of detections, by swab time point. Dark bars indicate no. of detections with another virus, and light bars indicate no. of single detections for that virus. Abbreviations: AdV, adenovirus; HBoV, human bocavirus; HCoV, human coronavirus; HMPV, human metapneumovirus; HRV, rhinovirus; MVI, multiple virus illness; PIV, parainfluenza; RSV, respiratory syncytial virus; SVI, single virus illness.