What Really Happens When Your Child Has a Virus? (Archived Pedcast)



Today I am going to take you back to biology class to learn about the type of infections that unfortunately your children are going to get a lot of…viral infections. We are going to review a little basic science so you can understand what is happening in your child’s body when they get sick with a “virus”.  Don’t you hate when you take your child to the pediatrician and they use the V word, virus! The reality is however, that most infections, especially in vaccinated children, are viral infections.  To doctors, we like viral infections. Viral infection to pediatricians usually means a relatively mild, self limited illness that needs no specific medicine other than symptomatic measures.  You know, grandma stuff.  Many parents however hate this diagnosis…they want a medicine to make things better now.  Let’s take a little closer look at how viral infections unfold and how your child’s body deals with them, shall we?

Musical Intro

Science Drive-The Biology of a Viral infection

To do this, we must go back to Science Drive, that intersection between Information Circle and Practical Way.  Recall that viruses are really not living creatures with a metabolism or the ability to self reproduce but rather they are little pieces of genetic material, either DNA or RNA, that have a covering called an envelope or capsule that protects the genes in the interior of the virus and allow it to move around.

When your child “gets a new virus”, these little packets of genes attach themselves to the cells that they infect, enter the those cells, and take over the cell’s activities, making the infected cell become a factory for more copies of the virus, more copies of itself!  Those copies then infect more of your child’s healthy cells. Greedy little things wouldn’t you say!  The cells that are most often infected are the surface cells that line your child’s surfaces that touch the outside world;  the cells of your child’s nose, throat, bronchioles, or intestines.  Now as the virus takes over, these lining cells, also called epithelial cells, first swell and stuff up and function poorly and then next begin to release the mucous that they have in abundance.   Finally, the host epithelial cell dies and sheds off with the eventual growing of new healthy uninfected cells.  That’s why your child’s nose gets very stuffy early in a cold (swelling of the surface cells) and then begins to “Run”, you know…let go of lots of mucous.  As the infection takes hold, the virus literally is jumping from cell to cell, gradually infecting  your child’s eye, or nose, or throat, or larynx, or bronchioles.  This is why your child’s sore throat on the first day often gradually turns into a runny nose and cough by the end of the third- fifth day.

Going from Biology to Your Child’s Symptoms

The process of the virus creeping through your child’s respiratory tract usually takes 3-5 days…hence what I call the rhythm of viral illness:

Day 1-Your child starts to feel badly, maybe with some fever, and some associated symptom like a sore throat or dry cough

Day 2-Your child feels worse.  Remember, the virus is spreading so there are usually more symptoms and more virus. Day 2 is usually the worse day with most viral infections, often the day with the highest fever.

Day 3- by the end of this day, 72 hours after the beginning of the fever, new infection of your child’s cells is usually slowing down and the amount of virus is beginning to fall quickly. Your child’s fever is usually goes away by now, and your child begins to feel better BUT they now have a lot of damaged cells and  maximal symptoms like cold, cough, runny nose, diarrhea. The virus that started all this havoc, it’s usually gone by now because your child’s immune system has inactivated it’s further spread.

This is what I call the rhythm of a viral infection. Day 1 things are bad, day 2 things are worse, and by the end of day 3-5, things are getting better but the child has the most symptoms like cough, runny nose etc. Now you know why that happens.

Most children take 7-14 days from the beginning of the illness to repair all the damage the virus caused, clean up the mess, and grow new healthy lining cells at the site of the infection.

How Can Your Pediatrician Help?

The problem pediatricians have is that when children are sick, they don’t come with labels. Your child’s pediatrician is an expert at sorting out viral infections that usually need no treatment from other, more serious sicknesses. If you have any concern about your child, take them in and let them help. That’s why they are there.

Here are some general rules about sickness in kids that might help you know when to go to the pediatrician:

-Fever in a child less than 3 months of age… get them checked!

-Fever persisting beyond the third day (72 hours)… get them checked!

-Fever present for a few days, then gone, and then returning…get them checked!

-Child acts really ill…get them checked!

-Fever with localized pain such as earache, facial pain, or the dreaded chest pain…get them checked!

-Any difficulty breathing..get them checked!

-Fever with a rash…get them checked!


Well, I hope that helps you understand one of the more common events in a child’s life… viral infections. Kids are germ fighting machines and usually handle the onslaught of recurrent viral infections without difficulty. If you enjoy learning about pediatrics in the pedcast format, go ahead and SUBSCRIBE at www.docsmo.com to get an email notice when I unleash new content, usually weekly. If you like podcasts on iTunes (now called Apple Podcasts), you can get your pedcasts there by subscribing to my iTunes feed. Or maybe you simply just want to send in a comment for others to hear.  I’m fine with that. Go ahead. join the conversation. This is Dr. Paul Smolen, hoping that the next time your child gets sick, you’ll know how those viruses do their trick.  Until next time.









Smo Notes: