Big Families at Higher Risk for Viral Infections

Researchers from the University of Utah School of Medicine claimed large familial units experience viral infections more often—87% of the year to be exact.

Their findings, published online in Clinical Infectious Diseases, was based on BIG LoVE (Utah Better Identification of Germs-Longitudinal Viral Epidemiology), a project dedicated to looking into virus’ behavior in Utah families. According to a statement released by University of Utah Health Care, these families were known to have the largest number of children per household in the country.

Since this allowed researchers to compare both large and small families, the team took nasal swabs from 26 families (n=108) once per week for a year. Using PCR-based diagnostics, a cutting-edge assessment which can produce results in mere hours, the samples were tested for 16 different respiratory viruses, including influenza, rhinovirus, and respiratory syncytial virus (RSV), according to the statement.

“Viral detection is often asymptomatic and occasionally prolonged, especially for bocavirus and rhinovirus. In clinical settings, the interpretation of positive PCR tests, particularly in young children and those who live with them, may be confounded,” the authors wrote.

Including a total 4,166 samples, the team reported a person in a one-child household was infected 18 weeks a year, with six children households having viruses 45 weeks a year. Conversely, families with no children were infected only 3-4 weeks annually.

“Children younger than 5 years reported symptoms more often and were more likely to have a virus detected than older participants (odds ratio [OR] 2.47, 95% confidence interval [CI], 2.08—2.94 and OR 3.96, 95% CI, 3.35–4.70, respectively). Compared with single person households, individuals living with children experienced three additional weeks of virus detection,” the authors wrote.

The study also challenged the validity of tests used to detect viruses. Of 783 viral detections, only 440 (56%) times were they associated with symptoms. Coronaviruses, human metapneumovirus, and influenza A were marked by a person showing signs of sickness while bocavirus and rhinovirus detections were rare since they were only sick for half the time the virus was in their system.

The use of PCR tests suggested that viruses could remain in the body even after a person recovered. The authors reported the “mean duration of PCR detection was ≤2 weeks for all viruses and detections of ≥3 weeks occurred in 16% of episodes.” However, young children had longer periods of PCR detection.

“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,” the study co-first author and professor of pediatrics Krow Ampofo, MB, ChB, said.

In the future, the investigators intend to look into viral behavior in larger communities that live in other areas and are of different ethnicities.