Westerners who visit Africa, particularly the off-the-beaten-track parts of Africa, often have little or no idea of the dangers involved. Some are obvious: war, terrorism, predatory animals, etc. Others, such as disease, organisms, etc. are less so - but they're no less dangerous. I was reminded of one such organism by this news report.
A British man nearly died after a parasite crawled up his penis and started laying eggs after he went for a swim in Lake Malawi in southeast Africa during a "holiday of a lifetime" with pals.
. . .
A week before Christmas he was diagnosed with schistosomiasis, an infection that's caused by a parasitic worm that lives in fresh water in tropical regions. It's most commonly found throughout Africa.
Once in the body, the worms move through the blood to areas such as the liver and bowel. After a few weeks, they start to lay eggs.
Some eggs remain inside the body and are attacked by the immune system. If it's left untreated it could have severe consequences.
There's more at the link.
I've had bilharzia. It's no fun at all. You can get it almost anywhere in Africa, and many of us who were born and raised there have endured its attentions. I've also had delightful encounters with things like Lassa fever (which is, in essence, an entry-level form of Ebola), malaria and a few other nasties, all of which, I'm glad to say, were cured before they finished me off.
That had amusing consequences when I moved to this country. I'd been a blood donor in South Africa, where (since so many have had these diseases and others) they'll accept almost anyone's blood and screen for whatever they need to keep out. The USA is a bit more picky. When I showed them my ten-gallon card, or whatever the high-number ID is, they got very excited; but when I told them I was from Africa, it was as if I was suddenly a walking, talking plague vector. Their attitude can be summed up as "AAAAAHHH! African blood cooties!" I was summarily informed that I could never donate blood in the USA, because I had antibodies in my blood that were powerful enough to spread infections to recipients without them, even though they wouldn't cause any difficulty in Africa (where almost everybody has them, in the trickier parts of the continent).
Moral of the story (and this is only partly in jest): if you go swimming in a bilharzia-infected stream, wear a condom!