Wednesday 6 July 2016

Kids are virus factories...

UPDATE #1: 06JUL2016
Ms. Mohinder Sarna and Associate Professor Lambert have just recently published some cool data from a large and very heavily sampled respiratory virus-related study.

The new report comes from a large birth cohort study entitled the Observational Research in Childhood Infectious Diseases (ORChID) study. 

ORChID is a "longitudinal community-based dynamic birth cohort study of ARI [acute respiratory infection] episodes in children from birth to 2 years of age in the subtropical city of Brisbane, Australia". The study followed babies until they were two years old, taking weekly - yes, WEEKLY! - respiratory swabs and dirty nappy swabs and then tested the heck out of them for known viruses and bacteria. 

The testing results are not part of this report so use of the term "infection" is presumptive. For this study I would have preferred ARI=acute respiratory illness; URTI-upper respiratory tract illness; LRTI-lower respiratory tract illness. But infection is being used in the sense of the clinical picture, where a long history of literature and prior knowledge informs a medical doctor's definition of these acute illnesses as most likley due to virus infection

The details of the study's intentions were previously spelt out in Observational Research in Childhood Infectious Diseases (ORChID): a dynamic birth cohort study.[1]

But the topic of this post is the latest publication from this cohort study: The Burden of Community-Managed Acute Respiratory Infections in the First 2-Years of Life.[2; unfortunately it's paywalled but abstract is visible]. 

I'm not reviewing the whole thing today, I just wanted to pick out a couple of bits and a figure because it really exemplifies how often our little darlings become ill. These are generally mild illnesses and usually without any long term problems. Of course, that doesn't make the grown-ups on the receiving of an infant with a very transmissible virus all that much happier!

A couple of interesting things:

  • this is a community rather than hospital-based study which gives us a real snapshot of what happens in normal life - interpret that with the knowledge that infants were "from families of more advantaged backgrounds, which is common in longitudinal cohort studies"
  • otherwise healthy infants in this cohort had a distinct illness every 2 months on average; fewer during the first 6 or so months but more after that 
  • sampling density is phenomenal - weekly samples. Also a good participant retention rate and 78% of expected days were captured
  • antibiotics were prescribed in 21.9% of all ARI episodes - usually for acute otitis media (middle ear infection), and more often for a LRTI than an URTI
  • when antibiotics were prescribed for upper respiratory tract illnesses (well known to be overwhelmingly viral in nature and thus not targeted by an antibacterial drug), it was most often in family physician visit older male doctors
    Note: Table 4 in the paper should not have had "Antibiotics" indented-personal communication with thanks to A/Prof Lambert for clarifying
  • some minor illness may have been missed because symptoms including fever, mood change and poor feeding are hard to measure in this very young age group.
    "I say mother, I'm feeling a tad peaked this morning". Umm, no. More like "Waaah!"

Copyright © 1999-2016 John Wiley & Sons, Inc. All Rights Reserved.
Publication: Pediatric Pulmonology; Content Title: The burden of
community-managed acute respiratory infections in the first 2-years of life;
Content authors: Mohinder Sarna,Robert S. Ware,Theo P. Sloots,
Michael D. Nissen, Keith Grimwood,Stephen B. Lambert.[2]
Reprinted with permission granted by Dr Sarna and RightsLink. License No. 3902730655132. 
Click on image to enlarge.
It will also be really interesting to see how often these children are infected but without a measurable illness resulting. 

What will the total number of infections look like in a year, in the community, among young children? More than a single infection every 2 months is my (highly biased) bet. That paper is coming, but unlike winter, it is not yet here.


I have also been a little involved with this study during my previous life, as acknowledged elsewhere.[1]

  1. Observational Research in Childhood Infectious Diseases (ORChID): a dynamic birth cohort study.
  2. The Burden of Community-Managed Acute Respiratory Infections in the First 2-Years of Life.
  1. Author title changes

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