The old man could have picked up the amoeba anywhere. Mostly young people are killed by it, because they’re more likely to swim in mucky places or play in dirt or mud. The victims might be getting it into the brain mostly by way of the nose.
It’s very rare for people to die from that, though, maybe because it’s difficult to get the amoeba into the brain. When swimming in murky water, avoid inhaling it. Don’t stick it up the nose when doing anything with soil.
I like swimming and fishing in murky lakes and ponds with algae floating on them. I also like planting vegetables in the yard. ;)
I used to swim in lakes on farms and loved doing so.
How do kids survive?