Re: Mysterious red lines
In that case you may need to focus on cleaning your toilet bowl, seat, handbasin, taps and toilet floor daily.
Make sure you both close the lid properly before flushing whether after urinating or other.
Keep your toothbrushes put away in a cabinet.
Dry your towels in the dryer on high heat daily if they are hung in the bathroom.
Some
parasite eggs can become airborne.
I do not know what product to suggest cleaning with.
There are enzyme sprays that kill smells may work on
parasite eggs.
You could spray with one called Full Marks that desiccates nits. WE can get that here in Australia in pharmacies.
I do not know if bleach is something that would protect your toilet area. I am thinking something more like a dessicater like pure vinegar or an enzyme spray or the Full Marks.