I have never heard of this? I wonder if we call it something different in the states?
Is it anything like rainrot? If it is, I use betadine wash for two days, then a mixture of 1/3 listerene (original formula,) 1/3 apple cider vinegar, and 1/3 water. I spray it on once a day for 3 to 5 days, and the rainrot is gone. If it starts to come back I use the mixture again. The betadine helps initially with killing the fungus / bacteria, and the listerene really keeps it gone, along with the apple cider vinegar. The water dilutes it.
Hope this helps, and good luck!