You can't wait for that dream holiday when you just lay on the beach and catch sun. But watch out: too much wet sand or swimming in the sea can harm your stomach. A team at the University of Florida has discovered that by spending more time on the wet sand or in the water you increase the chances of getting germs that cause gastroenteritis.

Water quality may be rigidly monitored in many tourist crowded beaches. But this is not the case with the sand.

"What we found was that there was no increased health risk due to exposure to sand on the upper beach. But the longer the period of time people spent in the water and in the wet sand, the higher the probability they would experience some gastrointestinal illness," Tonya Bonilla, of the Unievrsity of Florida's College of Veterinary Medicine's department of infectious diseases and pathology, told AFP.

The risk is posed by the feces of the seabirds. Microbes from these feces can turn naturally concentrated around the waterline and in the water, and plenty were encountered around on bathers' feet. The investigation was made on three beaches north of Miami: Hobie Beach, Hollywood and Fort Lauderdale.

"The probability that an individual will become sick increases over expected non-exposure rates from 6 out of 1,000 people for 10 minutes exposure to approximately 12 out of 100 people for a two hours stay in the wet sand. For exposure to water, these rates increase from 7 out of 1,000 people affected over expected non-exposure rates for a 10 minutes stay to approximately 7 out of 100 people exposed for a 70-minute stay," Jay Fleisher, professor College of Osteopathic Medicine-Nova Southeastern University, told AFP.