What about other health concerns and diseases in Thailand?

How to avoid malaria, dengue fever, cholera, dysentery, and other diseases while traveling

There is both malaria (largely in rural areas) and dengue fever in Thailand. Inconveniently, the mosquitoes that carry malaria are mostly active from dusk til dawn, while those that carry dengue fever are mostly active dawn to dusk. Some say this is a myth.

Either way, there are a lot of mosquitoes around all the time, and the standard advice is "avoid getting bitten" (which, in a tropical country like Thailand, is a bit like telling someone in a storm to avoid getting hit by the raindrops). (Here are all the details on mosquitoes in Thailand.)

As in much of the developing world, there are plenty of food and waterborne diseases (dysentery, cholera, liver flukes), so try to stick to bottled water or beer, bring a water purifier (like a Steripen or a Katadyn purifier water bottle) for when you can't, and avoid raw seafood or undercooked food.

If you do get diarrhea, it could just be a response to the fiery Thai cuisine or it could be a bug (mild or serious). Either way, play it safe until you feel better: stay in bed, drink tons of (bottled!) water to rehydrate, and stick to the BRAT diet: Bananas, Rice, Apples, and Toast.

While we're on the subject of diseases, bring condoms—and preferably use them with someone you love, not someone of negotiable affections.

In any event, if you feel seriously sick, go to the hospital. If you are worried about health insurance the like, see this page