How can I protect my health during international travel?

Me and my family go on international travel every few years and every time we come back to the US, I get sick. It takes me years of bad health to find out that I have a problem. I usually don't realize it till I am at my breaking point. Over the years I've realized that I've had parasites, candidiasis and other complications due to these. I've had parasites since I was 4 years old which was the first time I went on interenational travel and now I am 26 years old and finally realizing that my problems all these years were because of parasites.

I still do a lot of travel and getting treated for all these everytime I go abroad isn't practical. What can I do to protect my health when I travel?

as a frequent international traveler, i usually visit my primary care doctor to seek medical travel advice and get recommended vaccination few weeks before my trip.
while i am there, i eat only fully cooked food and fruits with peel;drink only boiled water or bottled beverages without ice. i use insect repellent that contain deet when i am outdoor. i always stay away from animals. i also bring small bottle of hand sanitizer and baby wipes with me.