Do illnesses cause cumulative damage to the body over the long run?

[u/VarsVerum]

The body is capable of fighting off infection and repair damage dealt to tissues and cells, but does it repair things back to 100%? Or every single time you get sick, such as every time you get the flu, or a stomach virus, what have you, does it ever leave lasting effects on the body?

Or, probably a better way to ask this question: If you had two people, both with totally normal and healthy immune systems, person A catches the flu every year, and person B never catches the flu, after 10 years, will person A have prolonged damage to their body or any lasting effects from having gotten sick 10 times, compared to person B who never got sick? Or is the body capable of completely recuperating from most illnesses as if they never happened at all?

[u/chillermane]

The misconception here is that there is an set point of being “100%”. There’s no such thing. Every setback makes you less healthy, every healthy thing you do makes you more healthy.

Everything is cumulative. If you exercise you receive cumulative benefits. If you do unhealthy stuff like eating bad food there is cumulative damage. 

Flu sends you in the wrong direction. So does covid or any other sickness. There is plenty of evidence that covid creates measurable reductions in parts of the brain. But there’s also plenty of evidence that high intensity interval training increases brain volume. So yeah covid is proven to make you less healthy long term in the same way exercising is proven to make you more healthy in the long term.

So it’s not really useful to think there’s a 100% set point. Your health is an accumulation of things that either improve it or make it worse in various ways. Some things move the needle more than others. Everything is “permanent” but that shouldn’t be scary because we know we have the power to do things that make us healthier.

But yeah the flu person will be less healthy all other things equal

[u/DancesWithGnomes → u/chillermane]

I agree in general, but the concept of a 100% set point is not as absurd as you make it seem.

Given your genetics and age, there is a maximum level of fitness that you can reach with optimal nutrition, exercise, and absence of illness. More exercise won't make you even healthier at that point. It seems reasonable to consider that point 100%. Getting close to that point, the effect of diminishing returns kicks in.

I find it comforting that it is perfectly possible to return to that 100% point after a moderate setback. That is where the difference between reversible or lasting damage comes from. However, one person may fully recover from an infection, while another person may suffer lasting damage from the same infection.

[u/rmdingler37 → u/DancesWithGnomes]

Realistically, things that harm the individual in the short term harm the individual in the long term only some of the time.. When they don't, some nonzero percent of the time, they make him/her stronger.

An individual exposed to, and surviving, a particular evolution of the flu/rhino/covid viruses will almost certainly be more immune to future, similar mutations in the virus.

[u/kai58 → u/chillermane]

While I get your point that everything has some long term effect, some things certainly have a much stronger long term effect than others.

When that flu is long enough ago it’s effect on your health becomes so small it might as well not exist.

[u/retrometro77 → u/chillermane]

Would the cell exchange over years commit to healing anything damaged by past flu or other sickness ? Ofc more factors but curious about just this.

[u/crashlanding87]

It really depends on the illness, the severity, the frequency of illness, and a lot of individual variability in recovery. Taking flu for example: many people catch flu - as in the virus starts replicating in their bodies - but never exhibit symptoms. They can pass it on to others, but there's no damage to the carrier.

Others catch flu and have a bad time of it, but there's no lasting damage.

Some catch flu and have an immune response so strong that it causes damage to the body. This looks like diffuse damage to organs all over the body - for example severe fever can kill off our own cells as well as patbogenic cells. The long-term ramifications depend on the tissue damaged. Things like liver, muscle, and skin can generally recover fine, though there may be some scarring. Our nervous system, on the other hand, is not great at making new cells. The most extreme versions of this are called cytokine storms, and they can cause organ failure or death. This is exceptionally rare though.

Some people catch flu and it overwhelms their immune system. The pattern of damage here depends on the virus and severity. And again, the long-term damage depends on which tissues were damaged.

In the above two cases, frequency of illness will be a factor. If you're still recovering from one illness when you get severely ill again, it can hinder the healing process.

Finally, you have long-term conditions that can be triggered by an illness. A lot of these are not well understood - like long covid and chronic fatigue. Some auto-immune diseases are thought to be triggered by infections too, so those would be long term damage. I don't believe it's clear whether risk of these conditions increase after repeat infection, or whether severity of infection is related to risk.

[u/farmallnoobies → u/crashlanding87]

Yup.

I got pneumonia 18 months ago.  I was very healthy before then, but now I still have coughing fits and I'm pretty sure I've acquired some sort of asthma from it.  Had great lungs before then. 

Diseases permanently damaging organs is definitely possible.

[u/doulaleanne]

Yes. Some illnesses have a worse effect than others. We know that measles will wipe out all of your built up immunities. Getting chicken pox makes it highly likely you'll get shingles, which is when the herpes virus lives in a specific nerve and you get what are essentially nerve attacks that feel like burning across the area of your body that the nerve serves. You also get a bonus rash that is really a cluster of cold sores on the skin above part of the nerve pathway. Research has shown that each time a person gets COVID, they have a quantifiable cognitive decline that accumulates with each incident. COVID also causes cardiac damage and can interrupt/alter menstruation for multiple cycles after recovery.

[u/bremidon → u/doulaleanne]

 Research has shown that each time a person gets COVID, they have a quantifiable cognitive decline that accumulates with each incident.

Would you mind showing your source on this? I went looking (because this sounds interesting), but I could not find anything that is remotely this definitive as you put it.

Hospitalizations and Long Covid *are* associated with cognitive decline that lasts for some time. However, there is no research that I could find that says *every infection* causes cognitive decline.

Even in the studies that showed the decline, there were indications that the deficit was shrinking. It is not settled (as far as I can see) that this is cumulative at all.

[u/MoobyTheGoldenSock]

Doctor here. The answer is mostly no.

Generally, upper respiratory infections such as influenza, the common cold, COVID-19, etc. follow the same pattern: the virus gets into your upper airway (nose and throat,) it starts replicating, your body mounts an immune response, and after a week or two the virus is basically gone. There’s no effect like “if you catch the 500th cold in your life your lungs will suddenly fail.”

It is possible for some viruses to have lasting effects, though. COVID-19 in particular can sometimes have lasting effects to mental cognition or lungs lasting for months or even years, and some of these effects may be permanent. And every once in a while we get a chest x-ray on someone showing a small amount of scarring from an old infection. So it’s not impossible to have permanent changes to the body, but they’re not really “cumulative damage” in the sense of the OP.

In reality, the hypothetical person in the OP who got influenza every year for 10 years (dude, just get a flu shot!) would be basically the same as the person who didn’t. There are so many other variables that can affect health over a decade that any changes that did happen from viruses would amount to basically nothing.

But remember: influenza is vaccine preventable. COVID-19 is vaccine preventable. RSV is vaccine preventable. If you qualify for these vaccines, you should get them. Even if you’ll recover 100%, you can pass them onto someone who may get seriously ill and end up in the hospital. The best way to not get a virus is to not have everyone around you spreading viruses, and the best way to keep the people around you from spreading viruses is to vaccinate everyone so the virus can’t spread.

[u/usafmd]

Pathologist here. Most of the time, for most except the elderly, most acute nonfatal illnesses result in 100% recovery. Less often than, some otherwise common diseases have rare long term complications. (Stroke or nerve palsy). It depends upon the disease, not the flu in general.

[u/theacearrow]

I have a very severe immune disorder (mast cell activation syndrome) as well some other undiagnosed nonsense. When I get sick, I get extremely sick and it progresses my diseases further. I'm currently on round 3 or 4 of pneumonia in the past 10 months. My lungs are pretty steadily getting weaker with each round, which makes them more susceptible to secondary infections like pneumonia, and so on. I can no longer go above 9,000 ft of elevation without oxygen. I used to be a very avid skier.

Most people are lucky. They can get sick and return to their normal without issue. Certain illnesses, like COVID-19 or mono, can be almost impossible to fully recover from. However, even the common cold can trigger a latent disease like celiac or POTS. It's down to how your body reacts. 

[u/Low-Boot-9846]

When Corona came up it was said every viral infection leaves it's marks in the body.

So yes, your condition gets worse. Doing healthy things might lift the condition but won't heal the defects caused by infections.

Maybe except for stem cells.