Tourists traveling to undeveloped areas may risk getting cholera, an acute intestinal infection.

Dr. James Runnels of the Baylor College of Medicine in Houston says that cholera vaccines are not highly effective.Runnels says the vaccine is "not very effective against old strains of cholera and is no protection at all against newer strains."

So the idea is to be careful about what you eat and drink. The cholera is carried in infected food and water, especially shellfish.

Runnels says many people who get cholera have no symptoms or mild ones. If symptoms do occur, they include vomiting, dehydration, abnormally low blood pressure, subnormal temperature, muscle cramps and shallow breathing and can include shock and even coma.