If you have a stomach virus, sometimes called the stomach flu, it's best to stay out of any swimming pool -- whether it's a public pool or your own. Bacteria, viruses and parasites that cause diarrhea and vomiting can spread through the water, infecting other swimmers and increasing their risk of getting ill, even in treated waters, according to an Australian study published in the American Journal of Epidemiology.
Swimming When Sick
While you may want to "tough it out," swimming and other exercise when suffering from the stomach flu or other virus won't help your illness. Working out when you're sick with a viral or bacterial gastrointestinal disease may slow your recovery, extending a two or three day illness by a week or more. Stomach flu can leave you dehydrated, weak and tired, with muscle pain and joint stiffness due to the fever, vomiting or diarrhea. All are dangerous conditions for swimming, especially if you swim alone. If you have a stomach bug, stay out of the pool for your own health and safety.
Stomach Flu "Bugs"
Many bacteria and viruses can cause stomach flu and the accompanying symptoms of diarrhea, vomiting, weakness, dizziness and sometimes fever. Among the most common viruses are the rotavirus, the norovirus and the enteric adenovirus. Bacterial infections such as salmonella can cause similar symptoms, as can parasites such as giardiasis and cryptosporidiosis. Any of these pathogens can survive in water. They're passed on to the next unsuspecting victim who swallows the water.
Contagion and the Pool
The microorganisms that cause stomach flu are highly contagious, which is why outbreaks on cruise ships and in other confined spaces are so prevalent. To prevent the spread of stomach flu, stay out of the water for at least one week after you recover from a viral or bacterial illness and for two weeks if you have a documented case of waterborne parasites such as giardiasis or cryptosporidiosis.
Spreading the Germs
Swimming pool water is chlorinated, which in theory should kill all the microorganisms that cause stomach flu. In practice, this doesn't always happen. Getting chlorination at the right level to kill bacteria and viruses without harming swimmers can be tricky, according to the Centers for Disease Control and Prevention. In the summer, the hotter the water, the more likely bacteria and viruses are to grow. And if you swim in an ocean, lake or river, there is no water treatment cleaning the water of pathogens. In a study at Australia's Monash University, researchers found that the risk of contracting a stomach flu was one to two times higher within seven to 14 days of swimming.