If our stomach contains a highly corrosive acid, how do viruses and parasites survive to be able to infect us?
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1. stomach acid doesnt dissolve everything, chewing gum famously goes thru intact and some pathogens can survive it too
2. most infections and diseases don’t get to us via the stomach, but by getting directly into our blood via cuts or mucus membranes.
Often these things come in to infect cells from different ways.
The nose and the throat have very soft ways in, these lead to the lungs and the blood stream.
So, breathe, swallow, you have a risk.
Normally, the body is great at fighting this..
Normally!
Your stomach is not the only route into your body. Here are two very common, very serious examples:
[Pinworms](https://www.health.ny.gov/diseases/communicable/pinworm/fact_sheet.htm)
[Schistosomiasis](https://www.who.int/news-room/fact-sheets/detail/schistosomiasis)
Your stomach is not the only route into your body. Here are two very common, very serious examples:
[Pinworms](https://www.health.ny.gov/diseases/communicable/pinworm/fact_sheet.htm)
[Schistosomiasis](https://www.who.int/news-room/fact-sheets/detail/schistosomiasis)
1. stomach acid doesnt dissolve everything, chewing gum famously goes thru intact and some pathogens can survive it too
2. most infections and diseases don’t get to us via the stomach, but by getting directly into our blood via cuts or mucus membranes.
Although not all viruses and parasites *do* survive to be able to infect us, when they do, it can be by way of the same chemical processes that protect our stomach. The stomach uses a mucus lining to protect itself; likewise, in the case of [influenza viruses](https://academic.oup.com/jid/article/216/1/105/3814252), our nasal mucus actually incidentally protects the viruses as they pass through the gastrointestinal system.
But there are other possibilities too. In the case of [the tapeworm](https://www.eurekalert.org/news-releases/652811), they have proteins that block the activity of digestive enzymes to prevent themselves from being digested. This also accounts for some of the negative side-effects of a tapeworm infection such as malnutrition.
Interestingly, some parasites [seem to have developed](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6860651/) to actually require exposure to corrosive stomach acids before they can hatch. Examples at that link includes the protozoan diarrheal parasite *Giardia* (which requires stomach acid exposure for excystment), as well as for the hatching of the eggs of the nematode *Ascaris lumbricoides*.
This requirement for acid exposure is similar to the [scarification](https://en.wikipedia.org/wiki/Scarification_(botany)) required for the germination of many plant seeds; it helps the parasites time their emergence from the egg, so that the next stage of their development occurs in the proper environment.
Although not all viruses and parasites *do* survive to be able to infect us, when they do, it can be by way of the same chemical processes that protect our stomach. The stomach uses a mucus lining to protect itself; likewise, in the case of [influenza viruses](https://academic.oup.com/jid/article/216/1/105/3814252), our nasal mucus actually incidentally protects the viruses as they pass through the gastrointestinal system.
But there are other possibilities too. In the case of [the tapeworm](https://www.eurekalert.org/news-releases/652811), they have proteins that block the activity of digestive enzymes to prevent themselves from being digested. This also accounts for some of the negative side-effects of a tapeworm infection such as malnutrition.
Interestingly, some parasites [seem to have developed](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6860651/) to actually require exposure to corrosive stomach acids before they can hatch. Examples at that link includes the protozoan diarrheal parasite *Giardia* (which requires stomach acid exposure for excystment), as well as for the hatching of the eggs of the nematode *Ascaris lumbricoides*.
This requirement for acid exposure is similar to the [scarification](https://en.wikipedia.org/wiki/Scarification_(botany)) required for the germination of many plant seeds; it helps the parasites time their emergence from the egg, so that the next stage of their development occurs in the proper environment.
Most of them can’t. The vast majority of bacteria and viruses you eat are in fact destroyed by stomach acid.
But there are a few that are well-adapted to surviving the human digestive system, and those are the ones that can make you sick. *H. pylori*, for example, which is both a common resident of your stomach and a common cause of stomach ulcers, burrows into your stomach lining quickly to get away from the acid.
(I am assuming you’re asking about foodborne illness. As others have noted, many other routes to infect you exist that aren’t through your stomach in the first place.)
Most of them can’t. The vast majority of bacteria and viruses you eat are in fact destroyed by stomach acid.
But there are a few that are well-adapted to surviving the human digestive system, and those are the ones that can make you sick. *H. pylori*, for example, which is both a common resident of your stomach and a common cause of stomach ulcers, burrows into your stomach lining quickly to get away from the acid.
(I am assuming you’re asking about foodborne illness. As others have noted, many other routes to infect you exist that aren’t through your stomach in the first place.)
Often these things come in to infect cells from different ways.
The nose and the throat have very soft ways in, these lead to the lungs and the blood stream.
So, breathe, swallow, you have a risk.
Normally, the body is great at fighting this..
Normally!
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