In what (common) diseases does having a strong immune system make no difference?

Factual Questions
21

I don’t think this is true. It’s just that if someone catches the flu and their immune system deals with it quickly, the person may be unaware that they even had the flu.
This happens frequently when encountering a strain of rhinovirus, say, that you’ve already encountered, but I can see no reason why this shouldn’t sometimes happen on encountering a new virus. And a stronger immune system would mean greater probability of early victory.

I think some posters above have given good responses, mainly citing those viruses that can cause severe sickness or death via an overresponse of the immune system.

If I may now hijack to more difficult examples that are interesting to think about:

AIDS – In the early stages, a strong immune system may help the virus spread more quickly, since it infects immune cells. But later on, it’s basically how many T-cells you have remaining that dictates your life expectancy, so you may still be better off overall starting with a higher count.

Prion diseases (which are of course infectious) – There is some evidence that the immune system plays some role here, and can help break up plaques. It’s not certain. But those that die from vCJD are typically young, implying (just implying) that the strength of the immune system is not the critical factor.

22

Again, what if you’ve never been exposed to any sort of flu virus whatsoever? Is any immune response even possible? Will you come down with symptoms/illness guaranteed? That’s what I was wondering.

23

I think Mijin has given the best response to this. When you’re immune system fights something like the flu off, you don’t know you had it. You might think you had a mild cold for a few days. I’ve only had a full blown case of the flu once in my life (I felt like I was going to die) but I’m absolutely sure that I’ve been exposed to various flus more often than that but my immune system must have got to them before they became a problem.

Imagine you have a population of a thousand people who’ve never been exposed to any flu virus. You put them in a commune together and introduce them to a strain of the flu. Some will die, some will get very sick, some will get a little bit sick and a small number might show few symptoms at all. That doesn’t mean they didn’t all get exposed to the flu, some of them just happened to have immune systems that more readily dealt with the threat.

24

The vaccine increases the probability that your body will be able to fend off the infection. It’s not a binary system, “unvaccinated people will get terribly sick while vaccinated people won’t notice a thing.” Vaccinated people can still get the flu and the unvaccinated may or may not get it; also, people who get it may get it to different degrees, from “24 shitty hours” to “one shitty week” to “R.I.P.”

Any school class where a kid has contracted the flu is a school class where all the kids and teachers have been exposed to the flu virus, but not all of them catch the flu - unvaccinated.

25

There’s a whole chunk of our defenses, the innate immune system, that doesn’t need doesn’t need to identify a virus specifically as, say, H1N1 flu virus; it just says, “Invader! Kill, kill!” Once the adaptive immune system gets the germs all analyzed, it can get involved too, so the body can attack the little bastards from all angles. But invertebrates do ok with just an innate immune system.

26

It really, really doesn’t need to.

Too late to edit . . . rashin, frashin, frishin. . . .

27

Or some of them were exposed to fewer invading organisms and were able to fight off the infection more effectively than those whose systems were (relatively) overwhelmed. Or some had better food and sleep and were more resistant to infection for those reasons.

The concept of “a strong immune system” is bandied about here and elsewhere without a good understanding of what that might mean. Without specific, reproducible measurements of components of the immune response such a description is meaningless. People who beat their chests and boast about how their immune systems are so good they never get sick, really have no idea about how their immune system works and what degree luck plays in their history of illness.

There are diseases like measles which are highly contagious, and having a “good immune system” is not going to help you. As previously noted, the “Spanish influenza” of 1918 killed a lot of young people with presumably good immune systems. And H1N1 has disproportionately affected younger people in contrast with typical seasonal flus.

People who actually do have a hyperactive immune response could manifest it by developing serious and even lethal autoimmune diseases. I’d be content with having an average immune system and helping it do its job by eating properly, getting adequate sleep and getting vaccinated for preventable diseases.

28

I’m 30 years old and a public librarian. I come into contact with a lot of germies. I’ve never had the flu. It’s ridiculous to say I’ve never met the flu. Therefore obviously my immune system fights the flu off, or at least it’s fought it off every time to date.

29

Effective immune systems are not likely to be much use against non-biological disease causing agents such as chemicals and hazardous substances.

30

An over-reactive immune system can sometimes aggravate problems. For example, gout happens when your immune system attacks uric acid crystals in your joints, causing inflammation and arthritic pain. Rheumatoid arthritis is also the result of the body’s own immune system attacking joints. An overreaction by the immune system also plays a role in eczema.

31

Cancer

32

One really does not have a “strong immune” system but so much as a strong immune response.

Here’s a good example. In the ebola outbreaks in Zaire (now Congo-Kinshasa), in the mid 70s, they found something very interesting, it wasn’t so much ebola but HOW you got it that determained the severity.

For instance, they found in Ebola-Zaire virus, if one got it through shared needles (the local health clinics reused needles), the death rate was over 85%. If one got Ebola-Zaire, through ritual body clensing (after people died, the locals would clean the dead body of fecal matter and such to prepare for burial), the death rate was just slightly over 50%. If one got it from improper barrier nursing the death rate was about 15%. With proper barrier nursing the death rate from Ebola-Zaire was less than 1%

So here’s the thing, the more time your body had to mount a defense system the better it was handled. A needle full of Ebola-Zaire stuck in you gave the body little chance to mount a defense. Improper barrier nursing gave the body a lot more time to pick up one or two Ebola-Zaire viruses and mount a defense against it.

In another case in West Africa, missionaires discovered the severity of Lassa Fever, which is endemic to the area can be measured by taking blood samples after exposure.

For example if you know you’ve been exposed to Lassa Fever on Monday, they take a blood sample on Tuesday and see your immune response. They can accurately judge how severly the Lassa Fever will effect you by seeing how quickly your body can mount a defense against it

Reseach also showed that low levels of immunity of ebola and marburg virus were seen in mid Africa. It wasn’t till a few years ago they found bats to be carriers of the virus. But it was interesting to see some people were infected with ebola and marburg (which are highly deadly) and never knew it.

If your immune system is healthy it has no trouble with things like Cold sores (once you get one it’s there forever, your body just fights the virus off) or latent TB. You can have latent TB for all your life with no problems. But if you’re body becomes too weak fightint off illness or is compromised (with HIV for example), the latent TB becomes active.

Latent TB is a huge issue in India and China where WHO estimates around 75% of each countries population has it. Latent TB is no big deal as long as one is healthy and HIV free. If not it becomes active and can spread.

33

With any autoimmune disease, the problem is that the immune system is reacting too much, to the wrong things. People with these conditions are sometimes put on immune-suppressing drugs.

Allergies are an immune response. I curse my immune system every spring and early fall when my allergies act up. I know I don’t have it as bad as people who have potentially deadly allergies, though.

34

I’d say, as a general rule, that for *communicable *diseases, the immune system will always play a role. Genetic/personal diseases (cancer, type 2 diabetes) not so much, though it may get involved in some ways.
As for the flu, as someone said above, the innate immune system kills anything that doesnt belong. The flu virus shows up, it tries to kill it. The vaccine works with the other half, the adaptive immune system. A vaccine is a dead or weakened virus. The innate immune system goes after it, but also revs up the adaptive immune system, which develops cells that *specifically *go after that virus. When the virus is gone, there are still a few cells around that remember that virus and can start up the adaptive response immediately if it returns. The problem with the flu, as mentioned, is that it mutates constantly. Enough mutation and the memory cells don’t recognize it, because they are very specific. Thus you need a vaccination every year for what the gov’t feels is the most likely strain to be around that year.
“Getting the flu” typically means that the virus has invaded and been able to multiply to the point that symptoms develop. But if your immune system kills an invading virus quickly enough, you will not develop symptoms even though you technically had the flu.

35

Interestingly, I just read that your blood type affects how easily you get cholera. O’s are more susceptible, AB’s less. I’ve always gotten the impression that cholera is the kind of disease that, if you drink enough of our friend Vibrio cholerae, you’re going to get it. It certainly seemed that way in The Ghost Map - that almost everybody who drank from the contaminated pump got sick - although of course 19th century Londoners may not have been the most healthy population to start with.

36

I very rarely get ill (in terms of having any symptoms or feeling poorly) despite being surrounded by sick people, and I have assumed it was due to my individual body and it’s capabilities. Interestingly I was a sickly child and adolescant, it’s only in the last 5 years as I improved my diet and habits that I stopped getting multiple illnesses yearly (in particular colds and strep, and frequent tonsilitis and sinusitis - and until I was 11 or 12 I had severe ear infections 5 or more times per year).

Before I cut out many common foods from my diet several months ago, I had lifelong autoimmune issues (frequent and varied skin reactions/rashes including chronic eczema, swelling/itching of the mouth and tongue, ‘hay fever’/dust allergies, symptoms indicating endometriosis, and IBS) - all of which are now gone. It’s quite interesting, the list of conditionsthat are known are suspected to be autoimmune disorders.

I didn’t see it mentioned yet that the gene (and associated change in hemoglobin) for sickle cell anemia (which as we know is seen in those of sub-Sharan African desent) is protective against malaria, and there is some evidence that carriers of the cystic fibrosis gene (mostly whites) have protecton against typhoid.

37

This isn’t quite true, as all of us have cancerous cells in our body throughout our lives, and for many to most of us, our immune system is on hand to take care of the problem and nip it in the bud so to speak.

Having a strong immune system certainly does help vs. various types of cancerous cells.

38

My wife suffers from an auto-immune disease called systemic scleroderma. Her immune system is overactive, and stimulates the production of too much collagen, which damages her lungs and digestive system, and causes her skin to become thick and hard. She is treated with immunosuppressant drugs, and has gone through two rounds of chemotherapy to reduce her immune response.

39

Not a disease per say, but altitude sickness can kill someone in great shape with a strong immune system. Other people are much less suseptible to altitude sickness. I’ve seen this first hand how one person get’s wiped out at 10,000 feet, someone else at 15,000 feet and others seem unfazed at 17,000 feet. Tibetans (and I guess Chileans) seem to have no issue.

40

Botulism. If someone else said it before me, then sorry.