[Petrochemicals (OP)]

I remember hearing something along the lines of "its not good news, he is showing no fever, so his immune system is not fighting the disease"

How accurate is this and is it different for viruses compared to bacteria ? If one where to get legionnaires you would show symptoms directly associated with it (i believe it is lung and heart) but is this because of some reaction by the bacteria ? If you got a cold virus you would sneeze and have a blocked nose, but are these symptoms because on the body  ?

[chris]

Part of the reason that we feel unwell when we are ill is because the immune response is releasing chemical signals called cytokines.

These circulate in the blood and provoke the symptoms of malaise that accompany illness, including fever, fatigue and aching muscles.

This means that, in general, the more pronounced the immune response the more severe the symptoms. And sometimes this can be maladaptive.

Indeed, in some of the patients I've treated in the past, giving them steroids to damp down the immune response has been helpful in mitigating their symptoms.

An example of this is the treatment of bacterial meningitis: when antibiotics are given, the dying bacteria release inflammatory debris that can provoke a very profound inflammatory reaction which can be destructive in its own right.

By blunting that response temporarily, you can improve the clinical outcome. Scientists recently showed that aspirin given as an anti-inflammatory can also be very beneficial in the treatment of TB meningitis: https://www.thenakedscientists.com/articles/interviews/aspirin-tuberculous-meningitis

Notwithstanding the above, it's not true that a person with a weaker immune response will feel better when challenged by the same infection, because they will most likely ultimately develop a more severe, invasive disease, which will compromise them in other ways.

So, the bottom line is that feeling unwell is a side effect of an immune response. But the absence of an immune response is not a guarantee of a symptom-free illness experience...

[Petrochemicals (OP)]

If these cytokines  that are released by the immune system are somehow responsible for the white blood cell reactions, does this mean that the white blood cells attack more virilantly and are less restrained in there targets ? You mentioned meningitis, so I suppose that is where the septicemia element comes from, the body attacking itself,  sepsis being given alot of coverage at the moment. I usually end up with the achey joints and think this may be down to my immune system rather than the infection, I don not think that achey joints help fight off the infection.

Would this also mean that when cytokines are released you are very unlikely to get a second infection in a simple flu like illness ? I have wondered on occasion whether I get 2 infections due to a lower health quotent, or one infection just hangs around a bit.

[evan_au]

a simple flu like illness ?

It might be more appropriate to describe the common cold as "simple"...

In addition to the runny nose, cough and fever of the common cold, influenza is likely to produce muscle aches, more severe headaches, more severe respiratory problems, and greater mortality in the young and the old.

A unique factor of the 1917 influenza pandemic was that it had a big impact on healthy young adults - it is thought that this particular virus put their immune system into overdrive.

its not good news, he is showing no fever, so his immune system is not fighting the disease

I had a friend who had leukemia. The treatment meant that he had very little immune response.
If he had even the slightest temperature rise, he had to go to hospital immediately, as his body was unable to fight the infection by itself.

is it different for viruses ?

As you may have heard, the world is tantalisingly close to eliminating the polio virus in the wild.
- In most people, it passes with cold-like symptoms
- In a few people, it causes severe paralysis - and sometimes death, if it paralyses your breathing

I recall seeing some studies where there was visible brain damage after a polio infection.
- Apparently, much of this damage was caused by the patient's own immune system
- I guess if the immune system had been damped down a bit, the symptoms may have been less severe?

See: https://en.wikipedia.org/wiki/Poliomyelitis