https://www.sciencedaily.com/releases/2013/01/130104143518.htm
“Increases in precipitation in some countries, due to climate change, will affect waterborne outbreaks of disease,” Apostolos Vantarakis of the University of Patros, Greece, said.
Storms and persistent rainfall can lead to sewage overflows, which releases water with bacteria and viruses into our waterways. Ingesting this water while swimming or engaging in other water sports can make people sick. People may think bacteria are the cause of such illnesses, but viruses are the more likely culprits. “In my opinion most of the outbreaks [of stomach bug] are caused by viruses,” Vantarakis says. “Yet we don’t know a lot about these viruses.”