I used a mild solution of bleach which I was told will kill off the spores when I had this problem in the floor and skirting as well as the walls in my kitchen in the bungalow. I also own a caravan and can't see any reason not to use bleach solution.
Tip
One thing don't be tempted to use bleach to clean the cassette toilet waste holding tank it damages the seals, even a weak solution.
Bob
June 2008