It sounds scary, but doesn't really seem to be that common. All the top search results are about one man who died from it.

But that's another benefit of synthetic/non-animal bagpipes - they have a zipper for opening it up and airing it out:
https://www.bbc.co.uk/news/health-37152871

"If you have a sheepskin bag, I was told that I should wash it out with hot water and bleach every year. That should get all the germs killed and prolong the life of your instrument.

"Of course, most people today tend to play synthetic bags. I tell my players that they can unzip those to let the bag dry out."