Serial viral infections in infants with recurrent respiratory illnesses

¹ Depts of paediatrics
² Biostatistics and Medical Informatics
³ Medicine, University of Wisconsin, Madison, WI

^* To whom correspondence should be addressed. E-mail: tuomas.jartti{at}utu.fi.

	Abstract

To better understand the viral etiology of recurrent and prolonged illnesses, we prospectively collected nasal secretions from 285 infants at increased risk of developing asthma. Of these, 27 infants had recurrent (5) moderate-to-severe respiratory illnesses (MSIs), and the viral etiology of their 150 MSIs and 86 scheduled visits was analyzed by molecular diagnostics. Their demographic and clinical data were compared to those with 0–4 MSIs.

Frequently ill infants had higher exposure to other children and more wheezing illnesses than less symptomatic children (p<0.0001). Viruses were detected in 136/150 (91%) MSIs, 14/21 (67%) mild illnesses and 29/65 (45%) asymptomatic visits (p=0.0001). Rhinovirus (HRV) was the most common etiologic agent (61%, 43% and 35% respectively, p=0.0020). Mixed viral infections were generally associated with more severe illnesses (27%, 0% and 5%, p=0.0001). Among the 27 frequently ill infants, only 8/150 (5.3%) MSIs were prolonged (2 weeks duration). Considering all samples, detection of the same virus strain 2 weeks apart was unusual (5.3% of all 244 positive findings).

HRV infections occur early, pervasively, and repetitively in these high risk infants. Infants with prolonged or recurrent respiratory illnesses most often have a series of infections rather than persistent infection with one virus strain.