Infections are the most widespread kind of illness in childhood.  An infection is when a germ decides to live on or in a person’s body, and causes problems or symptoms as a result.  Many germs can live on or in our bodies naturally, without causing problems or symptoms.   That’s not infection, it’s called colonization, and it’s often normal.  Some germs are never harmful, so when they are found it’s always considered colonization.  Other germs always cause illness, and so finding them on a person invariably means infection.  Still other germs can either colonize or infect, depending on the time, place, and situation.  These can sometimes be the hardest ones to figure out.

A germ is a small living thing, too small to see without a microscope.  There are many, many different kinds of germs.   They are divided into several broad "families": viruses, bacteria, fungi, and protozoa.  While the members of each family have many general characteristics in common, they do differ in the specific kinds of infections they cause.  Families, however, differ from each other much more drastically.  A bacteria is as different from a fungus as an animal is from a plant.  A virus is as different from a bacteria as an insect is from a mammal (or, perhaps more accurately, as a plankton is from a whale).  Millions of viruses could fit inside a single protozoa.

Antibiotics are drugs which kill (or at least stop the growth of) germs.  Antibiotic science is by far the most advanced in the realm of anti-bacterial medications.  Most of the antibiotics we have available for use today work against bacteria, and most known bacteria are susceptible to at least some of our antibiotics. Fungi and protozoa can be harder to treat.  While we do have some antibiotics which work against them, they tend to be more resistant to the action of these drugs.  Anti-viral science is still in it’s infancy.  We only have a few anti-viral medications available today, and they only work against a very few specific types of infection.  Most viruses are impervious to all drugs known to man.

Luckily, most viral infections are also pretty benign. Of course there are infamous exceptions (such as HIV), but when your doctor or nurse practitioner says, "It’s only a virus," what we mean is that it is an illness which requires no treatment because it will run it’s course and go away by itself, usually without damage or complications. In contrast, it’s a good thing we have anti-bacterial antibiotics, and we usually will use them if we suspect such an infection, because bacterial infections (while less common than viruses) tend to be more dangerous and less apt to spontaneously resolve.

No drug is perfect, and this is certainly true of antibiotics.  Not only do they have risks and side effects, but they also don’t always work.  When we choose which antibiotic to prescribe, we base that judgment on the likelihood of an illness being caused by a particular germ, and the odds of that germ being sensitive to the antibiotic.  Some germs "learn" how to resist antibiotics that they would usually be susceptible to.  Most clinical illnesses can be caused more than one germ (for instance, there are at least 6 separate bacteria that sometimes cause ear infections).   Thus, it is usually impossible to find a single antibiotic that kills all the germs that could possibly be causing a particular illness. If we can manage to "cover" 80-90% of the possibilities, we’re doing pretty well.

"Is it contagious?"  That’s got to be the most frequent question a pediatrician hears.  ALL infections are contagious!!!  Some spread more easily than others, and by differing routes, but that’s not really what matters.  People who focus on person-to-person spread miss the point.  Germs move through entire populations.  Contagion is a community based phenomenon.  The human race is to a germ as the ocean is to algae, or as the forests are to gypsy moths.  There are two major PATTERNS by which germs move through populations: endemic and epidemic.  Endemic is the less common.  An endemic illness exists at a certain low, possibly somewhat fluctuating but basically steady rate in a community.  Cases occur sporadically and semi-randomly. Person-to-person spread is important in endemic illness, as quarantine of a case might actually affect the odds of other cases occurring nearby.  The two most common endemic childhood illnesses in the United States today are Chicken Pox and Strep.   Most common childhood infections spread by the epidemic route, however.  An epidemic is like a wave moving through a community or region.  It touches everybody in it’s path, and knocks over all who aren’t strong enough to stand up to it.  When a particular germ is epidemic, it literally blankets the area.  It’s everywhere, on every doorknob, in every store, at every school.  You can’t avoid being exposed to it. In this situation, thinking that keeping one child away from another will affect anybody’s odds of coming down with the illness is simply naïve.  Epidemic illnesses include the common cold, most types of diarrhea & vomiting, most viral rashes and coughs, and most non-Strep sore throats.

So everything’s contagious, but that doesn’t necessarily mean isolating a child with an infection is a useful or logical thing to do. What else can be done?  HANDWASHING.  Hands are the dirtiest part of the human body, and most germs travel on them more often than by any other route. It has been shown time and time again that of all the "infection control" measures practiced in hospital settings, this is the one that has by far the biggest impact on infection rates.  It’s better than masks, gowns, and isolation rooms put together. Use soap and warm water, and wash frequently.  Wash before and after contact with someone who’s sick. Have the ill child wash before going out, eating, playing with siblings, watching the TV, and after going to the bathroom.  Wash on return home from anywhere.  The more often the better.  The more you wash, the less chance you give germs to spread.

It is important to remember it’s the germ, not the disease, which is contagious.  Often the same germ can cause several diseases, and the same disease can be caused by different germs. For example, the same germ that is causing a pneumonia in one person might only cause an ear infection in the next.  This is a matter of where in the body the germ "settles", and that’s a matter of luck, not contagion.

In general, we don’t know how long things are contagious for, even when treated with antibiotics!  The truth is that no good scientific studies have ever been done to address this question.  Physician’s over the years have developed "traditional", somewhat common sense answers such as, "until you’ve been on the medicine 24 hours", or, "until the fever’s gone", or, "until you’re feeling better". None of these have been proven for most infections.  We do know in a few isolated situations… we know for Chicken Pox, for instance, that it’s until all the lesions dry up.  We know that for "Fifth Disease", by the time the rash comes, the contagious phase is over.  These tidbits of certainty are the exception, not the rule, unfortunately.

While it’s important to treat with antibiotics when they’re needed, it is also very important NOT to use them unnecessarily. This is because germs learn! Ever since mankind discovered and started using the first antibiotics, we have literally been in a race with the germs to see if we could invent new ones faster than they could figure out how to resist them. For example, only 10 years ago 100% of Pneumococcus (the most common bacterial cause of pneumonia, ear infections, sinusitis, and meningitis) were sensitive to Penicillin. Today, 20-30% of Pneumococcus is resistant to that antibiotic, along with most others, and the percentage grows every year. These resistant Pneumococci are difficult to treat, and very dangerous as a result. Similar things have happened with other germs and antibiotics. It’s been inevitable that this would happen eventually since the day we started using Penicillin, BUT, the more Penicillin we use, the sooner and quicker the germs learn how to circumvent it. This plays out on a global, evolutionary scale - not at an individual level. Germs will not suddenly become resistant inside your child’s body while we or because we are treating with a particular drug. Still, we will all be safer in the long run if we resist the temptation to over-use antibiotics (as, for example, in the case of a viral infection). Because of this, it is our policy at Children’s Medical Office never to prescribe antibiotics over the phone. In general, we will need to do a physical exam first - and then we will only prescribe when we have made a specific diagnosis which requires antibiotic treatment, or when the likelihood of such a diagnosis is high enough to make the risks of not treating higher than the risks of doing so.

Another reason we do not prescribe antibiotics without examining you first is that it can be dangerous.  If your child had a more serious illness that really required treatment in the hospital with IV antibiotics, and we were to start oral ones before seeing you, we could "mask" the symptoms and cloud the diagnosis.  The resultant delay and confusion in realizing what was really going on could cause significant harm.

© 1998 Children's Medical Office of North Andover, P.C