I was just trying to suggest putting the towels in the dishwasher. The drying cycle is hotter than any water you´ll have in your home (unless you boil the towels) and it´s proven to kill almost any germ or bacteria.
I think yes with the detergent. Detergent actually makes water wetter -- it will cover and drown the bugs more thoroughly. Get a glass of water, you can float a needle carefully on the surface. Touch a piece of soap to it and the surface tension falls apart.