[Starman]

Why is it that animals seem to be able to drink untreated water but if we do it we become ill? Whole herds are described as healthy even though they drink this water.
Wild carnivores do the same are are described as being in excellent health.

[RickJ]

Generally, the immunities of humans vs. other animals are quite different.

This is not limited to carnivores. Animals of all kinds can, generally speaking, drink water (and even eat certain things) that would otherwise make humans quite ill - or even kill them. But of course there is some water (and some edibles) out there that also makes animals ill - or even die.

[Starman]

Generally, the immunities of humans vs. other animals are quite different.

This is not limited to carnivores. Animals of all kinds can, generally speaking, drink water (and even eat certain things) that would otherwise make humans quite ill - or even kill them. But of course there is some water (and some edibles) out there that also makes animals ill - or even die.

Yes, I know that animals are not totally invulnerable to everything they eat. Flamingoes become ill from drinking stool contaminated water for example. But in the case of the regular water that animals drink, you are saying that the immune system that protects them? I know that the Kimono Dragon has saliva which is full of death-dealing bacteria and he uses it to kill but it doesn't bother him one bit. So am I correct in assuming that the animal immune system works this way for any water that might have germs?

[RickJ]

Yes, Exactly.

[kp2171]

The animal perspective was never discussed in my human microbiology and parasitology courses...

But I'd guess that what was said about the immune system is to some degree true. We humans have bacteria in our GI tract that's called the "normal flora". Bacteria that is always there until sickness, meds, or something disturbs it. Then there is room for new things to move in, which can cause all kinds of problems.

When you study micro and parasitology you learn about the vectors that are specific to certain diseases... carriers of the "bug" that may show no sickness. This can be tied to a number of things. Maybe the parasite is at a different stage in its life cycle when its transmitted from animal to human. Or the animal has a innate tolerance for the "bug" that humans do not. Maybe the human is more sensitive to a by product of the microbe that the animal is not.

Truth is, we'd need a person w ties to vet/zoology to explain the reason why humans get severe diarrhea from giardia when traveling, but animals drink that water all the time.

I also wonder how much is sensitization... in that an animal that drinks taited water its whole life builds immunity against the microbes, as long as it survives. So the immune system builds up over time do to the increased exposures.

Baby's commonly get sick w rotavirus a few times in the first few years of life, puking, watery stool... but build up an immunity over time. Likewise, early challenges to the infant immune system can actually make it stronger in the long run (one high fever in the 1st year believed to be "good" to boost immune system as long as not too high).