Children and mother walking outdoors

Children and mother walking outdoors
In some families, it seems there’s always somebody who’s sick. When a group of researchers at the University of Utah wanted to find out if this situation is true or merely lamentations of weary parents, they didn’t have to look too far to find the ideal group of study participants. Families tend to run big in Utah, bigger than in any other US state, and 26 families of varying size agreed to participate. The findings of the study indicate the bigger the family, the more frequent the viral infections. The research team also thinks their findings might help physicians make more accurate diagnoses when children enter the emergency room with severe respiratory distress.


Senior author of the study, Dr. Andrew Pavia, is a professor of pediatrics at the Utah Center for Clinical and Translational Science, a branch of the University of Utah School of Medicine. His “Utah Better Identification of Germs-Longitudinal Viral Epidemiology (BIG-LoVE)” study followed 108 individuals from 26 households over the course of a year. Family composition varied and included three babies born during the study period.

Once a week, each family member submitted a nasal swab to the researchers, along with a diary of any symptoms that seemed to indicate a cold or influenza (the flu): wheezing, stuffy nose, fever, coughing, and such. A total of 4,166 nasal swabs were tested for 16 different respiratory viruses, including influenza, respiratory syncytial virus, and rhinovirus (common cold). Positive tests for presence of virus were compared to symptoms reported during the same week.

General Findings

The BIG-LoVE researchers discovered a direct correlation between household size and number of weeks a virus was detected in the nasal swabs:

  • The smaller the household, the fewer weeks of viral presence.
  • The number of weeks of positive viral tests increased with each child.
  • Youngest family members were more prone to viral infection than older family members.

The Bigger the Family

  • Families with no children — viral detection four weeks of the year (7% of the year).
  • Families with 1 child — 18 weeks of viral detection (35%).
  • With 2 or 3 children — 29 weeks of viral detection (56%).
  • With 6 children — 45 weeks positive for virus (87%).

Age Matters

  • Children younger than 5 years tested positive for viral infection 50% of the year (26 weeks).
  • Their parents were sick 1.5 times more often than parents of older children and childless couples.
  • Children 5 to 17 years old were positive 25% of the year (13 weeks).
  • Ages 18 to 39 were positive 22% of the time (11 weeks).
  • Age 40 and older were positive only 11% of the year (5 weeks).

Infection Without Symptoms

A positive test did not necessarily mean symptoms were present:

  • Children younger than 5 were 1.5 times more likely to exhibit symptoms than older family members.
  • Positive tests for influenza and parainfluenza infection matched respiratory symptoms almost all the time.
  • Infection with rhinovirus produced symptoms only about half the time.

Some viral infections lingered much longer than expected, even when no symptoms of infection were reported:

  • Most common viruses were usually gone in two weeks.
  • Bocavirus (bocaparvovirus) lingered as long as 12 weeks.

Sick Kids May Need More Tests

Since some viruses lingered longer than expected or produced short-term or no symptoms, the researchers conclude that it could prove highly beneficial if children who are presented to an emergency room or pediatrician’s office be tested for more than just cold or flu viruses, especially when severe respiratory illness is evident. If a more rare virus is present but undetected, the combined viral load could increase severity of illness and require specific treatment plans.


  1. Byington, Carrie L., et al. "Community Surveillance of Respiratory Viruses Among Families in the Utah Better Identification of Germs-Longitudinal Viral Epidemiology (BIG-LoVE) Study." Clinical Infectious Diseases (2015). Oxford Index / Oxford University Press. Web. 17 Aug. 2015.
  2. "Viruses Thrive In Big Families, In Sickness and In Health." University of Utah Health Care. University of Utah Health Care, 4 Aug. 2015. Web. 17 Aug. 2015.