Infant viral infections not causal for childhood asthma
MedWire News: Having frequent viral infections, such as rhinovirus, in infancy does not increase a child's risk for wheezing and asthma in later childhood, say researchers.
"Viral infections in infancy, particularly rhinovirus, are thought to be a risk factor for later asthma development, but it is unclear whether this association is due to the viruses themselves or whether rhinovirus-associated wheeze is merely an indicator of disease susceptibility," said lead researcher Anne van der Gugten, from University Medical Center Utrecht, the Netherlands, in a press statement.
"Accordingly, we examined the association between viruses during the first year of life independent of symptoms and the subsequent development of wheezing symptoms in childhood," added van der Gugten, who presented the data at the American Thoracic Society conference in San Francisco, USA.
The researchers enrolled 96 children who were followed up from birth until 4 years of age. Nose and throat swabs were collected at the start of every month during the children's first year of life to test for viral infection. Neonatal lung function was tested using the single occlusion technique before the age of 2 months before any respiratory symptoms manifested. In addition, the prevalence of wheezing at age 4 years (according to prescriptions/doctors visits) was recorded.
The team found that 13 (13.5%) of the children had wheezing at the age of 4 years. Compared with children who did not wheeze, those who did had decreased neonatal lung function.
The median number of rhinovirus infections in the first year of life was four in those with later wheezing and five in those who did not develop wheeze by the age of 4 years.
Children with a higher number of viral or rhinovirus infections during the first year of life that were accompanied by wheeze did have a greater likelihood of developing symptoms of wheezing by the age of 4 years, but this association became nonsignificant after adjusting for neonatal lung function.
"A number of prospective studies in high-risk cohorts have shown that viral wheezing illnesses, especially those caused by rhinovirus, are the most important predictors of the subsequent development of wheezing or asthma in childhood," van der Gugten told the press, "but it is unclear if rhinovirus is causally related to the development of asthma."
She added: "Our findings indicate that viral infections by themselves may not be associated with the development of asthma, but that children with reduced neonatal lung function are prone to experience wheezing during viral infections in infancy and to have asthma in childhood.
"Future research into the relationship between rhinovirus and wheezing disorders should account for factors that might modify this relationship, including neonatal lung function."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012
By Helen Albert