This is a sort of "but it's weird that it happened twice" thing, but I had a friend out researching Orangutans in I think Indonesia and he dropped dead after (supposedly) recovering from a fever.
Probably only a few years younger than your friend.
I've not kept up with his research but I suspect the species is almost certainly declining worse than when he was there.
Not sure what I'm saying, but yeah.
Weird that it happened twice.
It's so unprecedented!
/s