I was having a not-entirely-sober argument with a friend this weekend about the difference between illness and disease; she reckoned a disease was something not treatable, that you could not recover from, and I thought they were basically synonyms, differing only in colloquial usage.
A quick look at as many on-line dictionaries, medical and otherwise convinced me I was right, but most had very vague definitions of disease (e.g http://www.intelihealth.com/, the MW medical dictionary) that could conceivably be used to define, say, drunkenness as a disease (impairment of function due to environmental factors, i.e. ingesting alcohol).
Me and a colleague came up with the idea that drunkeness was a form of poisoning, and not a disease, but that left us the problem of defining “disease” and “poisoning” in terms that were clear enough for us to go “oh, yes!”.
I think an excess of alcohol can be seen as poisoning (I certainly knew a student who nearly died of it), and alcoholism is seen as a disease. That said, non-alcoholics can certainly suffer from alcohol poisoning. There’s a difference between the disease which leads alcoholics to drink and one specific instance of drinking, imho.
Well, I’m not sure I’m 100% with either of you. You can certainly treat (some) disease, and a successful skirmish with some illnesses can leave you not only not suffering with it, but positively immune to another bout (because your immune system now ‘knows’ about it).
I reckon that poisoning is the result of either ingesting too much of something which can harm you (deliberately vague) or the production of something internally having a poisoning effect as a byproduct of some other process (which might be biological), hence ‘blood poisoning’.
Disease seems to cover huge areas, from the body’s inability to ward off foreign biologicals (bacteria/virus), some kind of system failure (diabetes, for instance), susceptability to or failure to cope with environmental factors (eat too many burgers, fur up your arteries), immune system problems, you name it.
Diseases produce poisons. Poisons don’t reproduce; they do damage to your body purely on their own. They are either introduced to the body from the outside, or generated by things inside your body such as diseases. This is why it’s not necessarily a good idea to eat spoiled food that has been cooked since it spoiled–just because you killed the disease doesn’t mean the poison’s gone, too.
I’ll paste in the MW definition that is causing this trouble:
“an impairment of the normal state of the living animal or plant body or one of its parts that interrupts or modifies the performance of the vital functions and is a response to environmental factors (as malnutrition, industrial hazards, or climate), to specific infective agents (as worms, bacteria, or viruses), to inherent defects of the organism (as genetic anomalies), or to combinations of these factors”
Now, the last two definitions are fairly concrete and easy to understand, and my definition of disease would basically be that. However, the “response to environmental factors” seems to me to be extremely ambiguous. For instance, industrial hazards; this could mean mercury poisoning could be regarded as a disease. It seems to work for some things - i.e. asbestositis, which I believe amongst other effects kills macrophages by providing indigestible “trash” to clean up, but not for others.
Or am I being too demanding? Is “disease” too high-level a concept to pin down in the way I want?
johncole: I like that definition, and it has given me another idea; however my knowledge of biology is not good enough to be able to back it up, so if anyone can come up with exceptions…
A disease is anything that impairs the functioning of the body at a cellular level - this encompasses measles, cance, CJD, 'flu (which incidentally is the disease that started the whole argument - my point is that something that in 1918 killed up to 40 million people was definitely a disease).
A poison is something that affects the body at a molecular level, as a result of which the cells cannot function.
Unfortunately I don’t know anything about any poisons, so this may be completely barking up the wrong tree.