(CNN) – Health warning about swimming, popular activity in summer.
Heads of control and disease prevention centers reiterate the warning of a dangerous pest discovered in the pools.
The CDC warns of an increasing number of cases involving a dangerous parasite discovered in swimming pools.
"We want to urge the public to be aware of the issues and to take action to prevent them from getting sick," said Radhika Gharpure, a CDC officer.
CDC officials say that "crypto-parasitic" diseases have increased on average by 13% per year between 2009 and 2017. The lead author of the CDC report indicates that cases are warming in the summer because the parasite has an alarming quality.
"Even in a properly chlorinated pool, crypto can survive these levels of chlorine. And that's why it's so important to keep it out of the pool rather than trying to take it out once it's already contaminated, "Gharpure said.
Parasites cause severe stomach problems that can last up to three weeks. Most people are infected in places such as neighborhood pools when they accidentally swallow water containing human waste.
Health officials say that there are essential precautions to be taken to avoid getting sick. The first is to rinse before jumping into the water and to ensure the safety and cleanliness of the pool.
"When you swim, do not swallow the water you swim with. And if you are in contact with animals or in a daycare, be sure to wash your hands with soapy water, "said Gharpure.
The CDC says that doctors are now using a more accurate test to detect crypto-parasite. They predict more cases in the coming years.