ELi5: how do people discover new diseases and know it’s not just the common cold?
In: Biology
I’d just add that there is no one “common cold.” There are actually a bunch of different diseases, like corona virus, rhino virus, and adeno virus that can all cause a cold, and there are a bunch of different variations of those diseases. Additionally, some colds are actually just cold like symptoms caused by severe allergies, and no actual infection.
As /u/nowwithpulp mentioned, some diseases are definitely distinct from a cold.
Covid 19 was discovered because pneumonia is commonly caused by a couple different bacteria and viruses, most commonly bacteria of the pneumoniae family. But we’ve gotten really good at testing for these. So what happened was patients started getting pneumonia and they would test negative for all of the bacteria and viruses and other processes we normally look at in the lab. So after that we run more testing and bring in all the applicable specialists to make sure we didn’t miss anything. After that we’re left with a patient with obvious symptoms, x-rays showing they have a problem. But we have no known cause. We treat them as best we can and probably call it a day at that point.
Then someone else comes in with a similar problem, and then another, and another. By the time we’re up to 3+ people with the same symptoms and no known causes in a short time period you’ve pretty well determined that you have some sort of new communicable disease or there’s something in the environment.
You send more things to labs and ask them to look for anything in there that’s common between all the patients. They use a variety of methods to do this that I’m not familiar with. From there they can compare it to known organisms and see what it is and if it’s new.
Besides some disease having distinctly un-cold like symptoms- you wouldn’t confuse leprosy with the common cold, for example- we can look at the disease itself. Viruses look different from bacteria which look different from parasites.
Further, we can look at the genetic code of the diseases for areas that tend to stick around when things mutate- conserved regions- which help us see a diseases ancestry.
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