Like, we didn’t come up with a cure or anything, why didn’t it just keep killing
In: Biology
According to my wife (PhD in molecular biology, wrote her dissertation on tuberculosis) the primary cause is toilets.
When started installing technology that saved us from having to throw buckets of human waste into the streets regularly our levels of disease dropped faster than at any time in history.
Deadly diseases are self regulating. The more deadly a disease is, the faster it *burns* out. It simply kills it’s hosts too fast to spread effectively
Pandemics occur in areas with high concentrations of people. You remove the concentration of people, you remove the pandemic.
If I remember my European/world history correctly, it didn’t go away exactly, more like quit flaring up as dramatically. Multiple factors like population density, climate, weather, commerce, living conditions, other diseases weakening people, and so on would allow for epidemics to occur. The most famous occurrence, the Black Plague of the 1300’s, was the worst and most memorable of many outbreaks.
By the way people still get bubonic plague in some parts of the world, just not in endemic scale. Probably because of sanitation it’s not spread like it used to in Middle Ages. Still it’s not completely eradicated at all.
In general, infectious disease never keeps going forever in high rate, because as soon as number of healthy people drops significantly (due to getting infected, immunity, or death), transmission rate drops. Because there is no more available supply of fresh host to spread to. That’s the reason deadly diseases only comes in sudden waves and die down – not keep going. So the key to control infectious disease is to reduce number of susceptible people by any means. Vaccine, quarantine or getting them all infected all works.
Just want to add: if you want to read up on it, it’s called SIR model (Susceptible-Infected-Removed). It’s basis for all infectious disease models. It’s a bit mathematical though.
Simply put, killing your host isn’t usually the best survival traffic for a virus. The deadliest ones like MERS often don’t make it very far because they kill their host, and thus lose their home and their means of spreading.
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Through isolating people. The only way to stop certain disease is to keep healthy people away from sick people. Beyond rest and fluids, there isn’t much treatment, the infected either survived, or they died. Until vaccination, that was it. Stay away from people, isolate sick people. Treat the symptoms. The only things we have added to the response now are sanitation (we can do much better here) and vaccination.
Evolution. Some researchers now think that the bubonic plague didn’t kill indiscriminately, but that some people survived, causing evolutionary changes in immune system. Though this doesn’t necessarily mean that we’re all individually immune to a bubonic plague injection. There are also many different types of coronaviridae, like the rhinovirus, which we all get once in a while and usually causes nothing more than the common cold. I am willing to bet you that once upon a time, who knows how many generations ago, the rhinovirus used to be far more fatal, and that we’re all descendants of those with the right kind of immune system to not die from it.
They went away on their own once they had killed so many people that they exhausted their host population. The bubonic plague went away because it killed so many people that the survivors were distanced from each other, and the survivors were more genetically prepared to survive the plague. And because it only went away by exhausting its host population, it kept coming back every ~150 years as populations recovered. The only reason it doesn’t come back now is because we expect a higher level of cleanliness for ourselves, meaning no tolerating the presence of rats and fleas.
Spanish Flu was different, spread through the air and surfaces, was able to spread so freely because governments prioritized preventing panic over preventing death because they didn’t want the public to turn on the war effort, as had happened in Russia the previous year to the effect of a Revolution. It’s called the first modern plague because it was able to cross continents and oceans quickly thanks to industrialization, as a result, no one knows where it actually started. It was only called Spanish Flu because people thought it was especially bad in Spain because the neutral Spanish press was allowed to freely report on the pandemic. Spanish Flu killed 100,000,000 people, making it the deadliest single event in human history. And just like the bubonic plague it went away, not because of anything we did, but because it simply exhausted it’s host population. The ones who survived were just genetically better equipped to fight it off.
Nope, we didn’t come up with a cure, we tried to learn how they spread and adapted our behavior to curb the spread.
Even if we didn’t really understand the mechanism, we found a way to not die via trial and error.
It is the hallmark of our species. We don’t do things perfectly, just aim for the least terrible outcome and if that fails go to the next least terrible. Eventually one kinda works out. Well… not for everyone.
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