• Alex Cloherty

Can being sick be a downward spiral?

Updated: Aug 26, 2020

Welcome back to Microbial Monday! This week, we're kicking it off with a question from a friend. She wrote, "When you're sick, can you keep getting more germs from yourself or does it not matter anymore? I feel like once I’m super sick I’m just like, 'f*** it', and just touch everything and don’t sanitize my computer and phone and other stuff that only I’m touching. But can I actually be getting more germs back from myself and get sicker?"

To get to the root of this question, we first have to divide up the response of the immune system into two different parts: the 'innate immune system' and the 'adaptive immune system'.

Let's talk first about the adaptive immune system, which you might be more familiar with. You may remember from our discussion on the flu vaccine that our immune system has a memory. To put it simply, the adaptive immune system is the part of the greater immune system that has memory, while the innate immune system does not. This is the part of the immune system that encompasses antibodies and cells that can specifically target certain microbes for destruction. In other words, it acts like the police force searching specifically for the criminal on a "Wanted" poster. Sounds pretty good, right? There are a couple of catches, though.

The first catch is that both viruses, like influenza, and bacteria, like the whooping cough-causing Bordetella pertussis, are able to change the way they look to the immune system over generations. Here, you should take special note of the word 'generations'. Luckily for us, although bacteria and viruses can evolve pretty quickly to change, they still need a non-zero amount of time to swap costumes and hide from the immune system. With some notable exceptions (HIV, for instance), there isn't usually an enormous change in how a microbe 'looks' within the time of one person's individual infection. This is what allows the adaptive immune system to search out the microbe causing your current infection and ultimately clear it out from your body.

This leads us to the second catch: the adaptive immune system needs time to figure out exactly what the current invading microbe looks like and mount its defenses. Usually, this immunity army needs about a week to muster. So, what's protecting us from whatever cold or flu we have in the meantime?

That would be the innate immune system. This is the part of the immune system that has classically been thought of as the fast-acting bits that don't remember anything but respond blindly (although our understanding of this is changing... But we won't get into that here). Although the innate immune system does need a little bit of time to activate, it requires much less time than the adaptive immune system does – it's a matter of hours rather than days.

The trade-off for speed is that the cells and proteins of the innate immune system target foreign objects in a non-specific way, unlike the adaptive immune system. You can think of the screening method of the innate immune system like the customs lineups at airports. When you're entering Canada, for example, passengers might be split into two lines: Canadian citizen/permanent resident versus everything else. The innate immune system operates in the same way: body citizen/permanent resident versus everything else. If this part of the immune system sees anything that doesn't look like it's a normal part of your body – whether it is a wooden sliver, a transplanted organ, a bacterium, or a virus – it will react, and try to remove or destroy it.

Now that we understand the two branches of the immune system, what does this mean for our original question about potentially downward spiralling disease? In short, it means that you're unlikely to make yourself more sick by coughing all over yourself. Within a few hours of first being infected, your innate immune system will be activated, and give you some protection against the bug in question. Then, near the end of your infection, your adaptive immune system will have had time to muster, and will be on the lookout for the specific virus or bacteria that's been giving you trouble. Furthermore, in the weeks following your recovery, your adaptive immune system will be able to remember what the bug looked like well enough so that you won't get infected with the exact same bug again. In other words, if you cough all over your personal items while you're sick, you'll be protected against the particular virus or bacterium smeared on your laptop in the future. In summary, if the original bug tries to keep targeting you while your immune system is activated, it's analogous to a robber trying to target the same house again after the owners have had a high-tech alarm system installed.

That being said, although it's unlikely that you make yourself more sick by being a little less careful about your contaminated items, it's not impossible. Although your immune system will be working very hard to get rid of all the microbes in your system, continually re-introducing new ones will make its job a little bit harder – you'd be adding forces to the microbial army attacking you. Furthermore, you will never be alone in a room with just one type of bug. Remember, microbes are everywhere. It is theoretically possible that by being a little less cleanly when you're sick, you could end up catching a second bug while you're still recovering from the first one.

So, in conclusion, should you bother washing your hands over and over while you're sick? I would argue that it doesn't hurt. Although your defenses are already mounted against the bug you've got, extra cleanliness can only give your immune system a leg up.

Until next week - stay healthy!

~ Alex

#immunesystem #bacteria #viruses #infe #disease

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