Here's the
official advice (from the Food Standards Agency):
"If using re-usable cloths, make sure they are thoroughly washed, disinfected and dried properly between tasks (not just when they look dirty).
Ideally, wash cloths in a washing machine on a very hot cycle. A suitably high temperature can be obtained using a hot cycle of 90°C."
However the preferred approach is to use disposable cloths.
Source:
https://www.food.gov.uk/sites/default/files/media/document/cloths.pdf
Caran's approach meet with scientific approval though. Quote:
"Chris Smith, a consultant virologist at the University of Cambridge and the managing editor of the Naked Scientist, insists that you should boil your cloth in a saucepan"
Source:
https://www.theguardian.com/society/shortcuts/2018/sep/05/boil-your-dishcloths-how-to-make-your-everyday-environment-cleaner-than-a-toilet-seat
I'm actually surprised that people are still using dish cloths. (I don't know anyone who does). I use plastic sponge scourers and throw them out (very) frequently.