I know of a Chiang Mai girl who died after a brain worm infection. She was misdiagnosed for three months and realistically the infestation had been in her brain for six months before diagnosis. She was put into an induced coma, the worms were killed off but complications killed her.
Thais routinely take anti-parasite medicine, usually twice a year. It's available over the counter at pharmacies. Raw prawns are infamous hosts for parasites but undercooked fish is also a problem. There's no shame in asking for the meds, it's not a reflection of your hygiene, it's a reflection of the sometimes dubious foodstuffs that we are presented more than anything.