There have been reports of YouTubers I watch getting sick after eating food in third world countries. However, these countries are also home to a large number of people who do not get sick from eating the same food. I think this suggests that the locals may have developed stronger immune systems. What do you think?
Not necessarily, it is likely that a tourist is just not used to these specific pathogens. While the people living there are used to them. So their immune system isn’t better per se just more adapted to the environment.
Also “survivorship bias” sadly plays a part in this. The healthcare is low quality or nonexistent. Everyone seems to have an excellent immune system because most everyone that didn’t… died.
Not sure what country you’re talking about but as someone born and raised in a third-world country with free, universal healthcare I can tell you I’m offended.
Man I really think this highlights how badly we need to stop using the word third-world. Thanks for pointing that out. It is antiquated and just used arbitrarily these days. I was trying to convey war-torn countries, countries with too much unrest to support a universal healthcare system, etc. Those descriptions are not descriptive of every third-world country.
Same sort of idea if you went to a small culture in a third world country who isn’t used to eating any fast food, and gave them McDonald’s. They’d be diarrheaing all over the place because they’re not used to it.
True, I moved to a foreign country, but Europe to Europe. I could’ve shit through the eye of a needle for the first three weeks, then was fine after
The gut microbiome is absolutely wild. We are just delusionally egocentric mobile meat-homes.
I find the OP’s question very intriguing and have kind of arrived at this same conclusion. My only tweak would be that they may, in fact, have more effective immune systems purely due to the fact that access to medicine or areas free of pathogens aren’t as common. Obviously, though, that would be compared to a person who exists in those same conditions but with access to good medical care which is a bit paradoxical.
EDIT: I made this more complicated for myself by thinking, further, that nutrition would also play a huge role in this
There is no such thing, generally speaking and outside of particular medical conditions, as a “strong” or “weak” immune system.
There are two different factors being smooshed together.
One factor is general health and healthcare. A healthier individual – no dietary deficiencies, well-rested, medical conditions treated, etc… will generally just fare better when exposed to a disease. People in richer countries typically have better health.
Take cholera as a classic example. To a person in good health with access to water, cholera is a bad time, but unlikely to kill you or do permanent harm. To a person who already had nutrient deficiencies without access to abundant, clean water, it’s a potential death sentence. This doesn’t mean someone from a rich country had a “stronger” immune system. That person was just able to refill their personal health bucket faster than it drained thanks to those resources available to them.
In some cases, this is literally true. For example, being underweight is a worse comorbidity than being overweight by a similar amount, all else being equal.
The other factor is the immune response. Immune response is about exposure and recovery. You gain immunity to the pathogens you are exposed to as part of the recovery process. There’s very little correlation between having an immune response to one disease and being better at fighting off another, different disease (though with quite similar things like strains of the flu, there is benefit). There’s no such thing as “exercise” for your immune system. There is no evidence of overall strengthening caused by more exposure and recovery. Occasional studies come out that try to make this claim, but nothing very convincing has ever happened. That immunity response, in some cases, can diminish over time without re-exposure. There is precisely one medically sound and safe way to promote immunity: vaccination to relevant pathogens.
But if we’re talking about “Don’t drink tap water in Mexico” kinds of situations, it may APPEAR that way.
The reason locals don’t get sick from the things that hurt tourists is because… they do. They did. It already happened, you just didn’t see it. If you take someone from a very rich, healthy place and someone from a poor, unhealthy place and locate them both to a foreign environment with background pathogens to which they are not exposed, both are likely to get sick.
I live in a third world country. What you don’t see in those YouTube videos is how common it is for the locals to contracts sanitary-related diseases such as typhoid fever, hepatitis A, ascaris worms, diarrhea, etc. A large proportion of people I know (including myself) have contacted typhoid fever at some point in their live. Those street food resistance is earned by getting sick a lot when they’re young.
It’s usually the water that makes people sick. When people from third world countries move to first world countries and live there for a couple of years, they will get sick too when they revisit their home country.
There was an episode of vsauce or veritasium or cgpgrey several years ago that kind of talked about this a little bit. Basically, inside and outside of us, alongside covering all of our things and everything we touch and are around and other people, are all part of an extended network of poop particles and bacteria.
You get sick when new things get past your exterior & interior poop network of bacterial defenses. Same for anyone, anywhere. It’s all just how much, how fast, and how far and how new, the new bacteria and viruses get. If it gets too far, too fast, we might die.
But, people are disgusting and COVERED IN POOP BACTERIA AND VIRUSES and so we’re all fairly familiar with everything, and nothing is too different.
COVID-19, for example, was very different and spread in large amounts very quickly, I believe it’s why it’s called a “novel” virus. It was different enough that it just waltzed past all our defenses and killed millions of people. And then, it mutated enough, and quickly enough, that when it came back to us with the new form, our immune systems were like “damn this one virus came in here and caused a ton of damage, but for some reason we don’t know exactly what it looks like. Are you that virus or it’s relative?” And the mutation was like, “uhhh, no?” And the security guard/immune system was all, “okay, come on through.” And it would get us sick again.
Biology is weird and epidemiology is incredibly difficult when half the population is fucking homeschooled and thinks horse dewormer helps this type of thing or that it’s fake or something.