As summer gets under way, the Centers for Disease Control and Prevention has issued a stark warning for travelers: Beware of the hotel pool. Between 2000 and 2014, nearly a third of the disease outbreaks linked to recreational water facilities occurred at hotels, inns, and lodges, the CDC reports. Cryptosporidium, or crypto, was the culprit behind 58 percent of the outbreaks with a confirmed source. This parasite, which wreaks havoc on the digestive system, is highly tolerant of chlorine and can survive for days in well-maintained pools and hot tubs. “Swallowing just a mouthful of water with crypto in it can make otherwise healthy kids and adults sick for weeks with watery diarrhea, stomach cramps, nausea, and vomiting,” the CDC’s Michele Hlavsa tells CBSNews.com. Legionella bacteria, which can cause pneumonia, accounted for 16 percent of the reported outbreaks; 13 percent involved Pseudomonas, a group of bacteria responsible for “hot tub rash” and “swimmers’ ear.” The CDC advises people to avoid getting pool water in their mouths, to shower before swimming, and to avoid pools when sick with diarrhea.