Monday, August 10, 2015

CID: Viral Detection Increases With Family Size


Credit University of Utah School of Medicine


# 10,400


Although it is hardly a `stop the presses!’ moment when researchers reveal that kids get sick more often than adults, the results of the recently published BIG-LoVE (Utah Better Identification of Germs-Longitudinal Viral Epidemiology) study by investigators at the University of Utah School of Medicine nonetheless provides some fascinating results.


The University of Utah Health Sciences press release describes how the study was conducted:


Investigators monitored 26 households collectively made up of 108 individuals (three were born during the course of the study) for one year. Each household collected nasal swabs from family members once per week and documented when they had symptoms typical of cold and flu. A PCR-based test, the FilmArray by BioFire Diagnostics, probed swabs for 16 different respiratory viruses, including influenza, rhinovirus, and respiratory syncytial virus (RSV). 4166 samples were analyzed in all.


Households without children typically tested positive for one of the 16 respiratory viruses  3-4 weeks during the year (7%), while adding 1 child to the household increased that number to 18 weeks (35%). A five-fold increase.   Households with six kids had detectable viruses 45 weeks out of the year (87%).


Yet, despite these rampant PCR detections, only about half those who tested positive had cold and flu symptoms.


Those who tested positive for influenza and parainfluenza viruses were symptomatic most of the time, but only half of those who carried a rhinovirus reported symptoms . You may recall that in 2012’s The Very Common Cold, we looked at a study of college students (an older cohort than BIG-LoVE) where only 1 in 4 who carried a rhinovirus was symptomatic.


Another excerpt from the press release:


What's more, results suggest that even after a patient recovers from an illness, some viruses persist for weeks afterward. Bocavirus persisted in the nose for as long as 12 weeks, but more commonly viruses persisted for two weeks or less. In an accompanying commentary also published in Clinical Infectious Diseases, Gregory A. Storch, M.D., of Washington University School of Medicine in St. Louis, noted that the research "provides highly useful information," especially concerning how long PCR-based tests remained positive during each viral episode.

If presence of virus doesn't always translate into illness, then it stands to reason that even if someone is sick and tests positive for a specific virus, there could be another cause. For example bacteria, or a rare virus not detected by the test. Health care providers should be aware of these limitations.

"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," says co-first author and professor of pediatrics Krow Ampofo, M.B., Ch.B.


A link and some excerpts from the study follow, after which I’ll be back with a little more on flu vaccine uptake for kids, and how you can help researchers track symptomatic respiratory illnesses:


Community Surveillance of Respiratory Viruses Among Families in the Utah Better Identification of Germs-Longitudinal Viral Epidemiology (BIG-LoVE) Study

Carrie L. Byington1,a, Krow Ampofo1,aChris Stockmann1, Frederick R. Adler2,3Amy Herbener1, Trent Miller4, Xiaoming Sheng1, Anne J. Blaschke1, Robert Crisp4, and Andrew T. Pavia1



Results.  Participants reported symptoms in 23% and a virus was detected in 26% of person-weeks. 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 3 additional weeks of virus detection. There were 783 viral detection episodes; 440 (56%) associated with symptoms. Coronaviruses, human metapneumovirus, and influenza A detections were usually symptomatic; bocavirus and rhinovirus detections were often asymptomatic. The mean duration of PCR detection was ≤2 weeks for all viruses and detections of ≥3 weeks occurred in 16% of episodes. Younger children had longer durations of PCR detection.

Conclusions.  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.


Since kids are essentially walking Petri dishes, and school rooms are perhaps the most efficient viral exchange environment known to man, there has been a good deal of discussion over the years on focusing influenza prevention among children.  


While flu vaccination rates continue to inch up, anti-vaccine rhetoric and the general belief that only the elderly and those with co-morbidities are truly vulnerable to serious influenza illness, have kept vaccinate rates lower than desired.  


National Early Season Flu Vaccination Coverage, United States, November 2014


For the past 4 years  I’ve promoted the idea that my readers take part in the Flu Near You project, a partnership between HealthMap ( at Boston Children’s Hospital, the American Public Health Association (APHA, and the Skoll Global Threats Fund (


Not only does my 30 second weekly contribution add to the wealth of data being collected on ILIs (influenza-like illnesses) around the country - and shares that information publicly - I have a convenient track record of my own `flu’ history going back 5 years.


Once a week you receive an email with a link. Click on it, and you will be presented with a quick questionnaire. 


With luck, all you have to do is click the last option.  But if you did have symptoms, you simply click the ones that apply.  Although I’ve tried to be diligent, I discovered this morning I’ve missed a few reporting weeks. 


Still, 96% participation is a pretty good batting average.


I also discovered, looking back, that I only reported `flu like’ symptoms (in this case, a cough and sore throat) once during the past four years. A testament no doubt to my age (61), the fact that I get the flu shot every year, I’m fastidious about good flu hygiene year round, and I live alone.


Given the wealth of data it produces, I would encourage my readers to check out the Flu Near You site, and consider taking part in this project.

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