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According to an American cohort study, children younger than five years carry respiratory viruses fifty percent of the time. This is not always accompanied by health complaints: symptoms were only reported in 37 percent of the study time, researchers from the University of Utah state in Clinical Infectious Diseases.

In the study, 26 families with a total of 108 members were asked to keep a respiratory symptom diary and to obtain nasal swabs of each family member once a week. These were used to detect the presence of several different virus strains.

As may be expected, young children carried viruses more often and had more respiratory symptoms (37 percent of the year) compared to their older family members (20 percent of the year). Furthermore, families with children had more illness episodes than households without children, irrespective of the number of offspring. “A lot of families go through wave after wave of illness. In fact, some of the kids we monitored had symptoms for 20 to 25 weeks in a row,” says co-first author Carrie Byington, professor of paediatrics.

Remarkably, common infections with the bocavirus or rhinovirus were asymptomatic in fifty percent of the cases. Detection of these viruses in a sick patient may therefore be misleading, the scientists conclude. Co-first author, Krow Ampofo, professor of paediatrics, warns: “If a child comes into the emergency room with severe respiratory illness and tests positive for rhinovirus, it might be a smart idea for doctors to make sure they’re not missing something else that could be the cause.”

Sources: Clinical Infectious Diseases, University of Utah

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