Why do we catch diseases?

snowfreeze, BSN, RN · Oct 15, 2005

Ebola has been around for a long time and has never eradicated all mammals. Opportunistic is the key here. The weak die, the strong survive and the lucky get another chance.

RC1 · Oct 16, 2005

The weak die, the strong survive and the lucky get another chance.

That doesn't apply to humans anymore, not in advanced countries at least. I'm sure it still works that way in Africa and other impoverished high population regions where selection is still natural though.

Survival of the fittest is the race here on earth.

Whenever I hear that term, "survival of the fittest" I have to point out that "fittest", in the Darwinian sense, is a measure not of health necessarily but of reproductive success. It would be more precise to say, "survival of the creatures that are able to make the most copies of themselves before they die."

Ebola has been around for a long time and has never eradicated all mammals.

Perhaps the conditions necessary for it to "work its magic" have never fully been realized. The advent of commercial air travel is one of those factors that greatly increases the ability of a bug to cause disease. I'm sure there were plenty of deadly diseases that weren't a problem to most of the world until the etiological agent was able to hop a ride on a carrier bound for a new country full of susseptible hosts. Look at the havoc that European pathogens wrecked among Indian populations in early America as an example.

loricatus · Oct 16, 2005

realnurse said:

thanks a lot for your good respond but can u please give me the evidence for this, what I mean is from which book or journal or web site, please if possible with full resources , thanks again

It might help if you do a Google or dogpile search under IMMUNOBIOLOGY LECTURE NOTES-you'll get a lot of different full resources along with different explanations for the concepts. One good site is:

https://ocw.mit.edu/courses/hst-176-cellular-and-molecular-immunology-fall-2005/pages/lecture-notes/

realnurse said:

We all know that our immune system is very strong so, why do we still get diseases?

Why does our body still get infected with viruses? What is the reason?

Another way you might try to look at it is that our immune system is working because we frequently recover (don't die) after an invasion from pathogens-that which does not kill us only serves to make us stronger type of outlook.