What's called medical tourism – patients going to a different country for either urgent or elective medical procedures – is fast becoming a worldwide, multibillion-dollar industry.

The reasons patients travel for treatment vary. Many medical tourists from the United States are seeking treatment at a quarter or sometimes even a 10th of the cost at home. From Canada, it is often people who are frustrated by long waiting times. From Great Britain, the patient can't wait for treatment by the National Health Service but also can't afford to see a physician in private practice. For others, becoming a medical tourist is a chance to combine a tropical vacation with elective or plastic surgery.

And more patients are coming from poorer countries such as Bangladesh where treatment may not be available.

Medical tourism is actually thousands of years old. In ancient Greece, pilgrims and patients came from all over the Mediterranean to the sanctuary of the healing god, Asklepios, at Epidaurus. In Roman Britain, patients took the waters at a shrine at Bath, a practice that continued for 2,000 years. From the 18th century wealthy Europeans travelled to spas from Germany to the Nile. In the 21st century, relatively low-cost jet travel has taken the industry beyond the wealthy and desperate.

Countries that actively promote medical tourism include Cuba, Costa Rica, Hungary, India, Israel, Jordan, Lithuania, Malaysia and Thailand. Belgium, Poland and Singapore are now entering the field. South Africa specializes in medical safaris-visit the country for a safari, with a stopover for plastic surgery, a nose job and a chance to see lions and elephants.