From the
CDC and
USDA articles I've read, Campy is extremely common.
It's so common, that I wouldn't be surprised if our bodies deal with it on almost a daily basis. People get ill from it when they encounter an excessive amount all at once, and the body just can't deal with it all. Healthy people generally recover within a week.
Also, there is a key phrase in the first sentence of that article;
Another type of bacteria which could potentially be fatal to a dog when the immune system is compromised is Campylobacter.
When you see that phrase, you should automatically think
"the very young, and the very old" (or those on imuno-suppressant drugs).
The fact that your brother's cat was quite young when it came down with the associated illness could be a factor.
It was also mentioned in one of the articles I read that freezing can reduce the bacterial load.
I always rinse my meats well before processing and freezing, and have not had any issues so far.