Help!,rat invasion!

This tragedy happened a week ago when rainy season in my state(where rats were known to invade houses). I was watching TV alone that midnight when suddenly I heard weird noises came from my bathroom,I then check my bathroom and I found out a black,nasty,big rat just jump out of my bathroom. It freaks me out(I swear that is the biggest rat I ever seen). He saw me for a second then fled away under my sofa. I still see him run around when I randomly wake up at midnight to urinate(it could be the same rat or another rat). We’ve tried some poison food specifically designed to eliminate rat but he didn’t even touch that food,turn out it’s eaten by ants. We’ve also tried to use rat glue,but it too didn’t work as we expected. How could he came from my bathroom?,from my toilet?,I sometime feel unsafe when I need to use that toilet. So how could we deal with this nasty creature?. (Exterminator is not available in my country and I won’t let my cats catch disease from this creature). Any suggestion?. Please help!.