I want to tell a tale about what happened on our recent cruise. On our first day at sea my wife developed a very bad case of diahrrea. It was very bad and by the time we went to the doctor on the following morning she was dehydrated.
The medical service was very good. They gave her iv fluid to rehydrate and drew blood to make sure that it wasn't norovirus. They gave her antibiotics and anti diahrreal meds. They checked up her, and followed up the next day with a second iv. They even sent a bowl of fruit.
However, none of this was free, well the fruit was, but the bill for this treatment was over $1600, which we had to lay out. Luckily we had travel insurance through AIG. They collected all of our paperwork, and did some background to my wife's health. They called a couple of days ago to say that they were sending us a check for $1500, covering the cost except for a deductable.
So my point is it is important to have travel insurance, especially if you are traveling overseas. And get it from a reputable agency.