Talk to Gastroenterologist on Parasite Infection

I recently ran a CBC test, and my eosinophils were slightly high. I don’t have any serious stomach issues, but I have low weight despite eating a healthy diet with juices, and my skin looks pale. Recently, my cousin was diagnosed with a parasitic infection.

In his case, the stool and parasitology test were clear, and even the CBC was also normal. He only had low blood counts, so the doctor ran a liver test, and that’s when they found something was wrong, as his liver was damaged.

This makes me worried: how can a normal family member identify what is wrong if the basic tests (like CBC and stool test) are clear? We live in a joint family system is there a chance the infection can spread between family members? how to prevent early to safe organs.

Also, if basic tests don’t show signs, is it okay to take antiparasitic medicine once in a while, just to be safe? If yes, should it be taken for one day only, or for three days?

Please guide me.