1,107. Are Lice a Chatzitzah?
161:18 A woman should not immerse with dust on her feet. If she did, if it was thin dust that would be washed away by the water, the immersion is still valid.
161:19 Lice and fleas do not typically stick to the body. The water reaches these places and they are not a chatzitzah. However, lice that cling to the body and bite where hair is must be removed by using hot water and pulling them off with her nails. If she is not able to remove them, they are not a chatzitzah. Small lice that cling to hairs must be removed because these are a chatzitzah.