By Stephanie Stahl

By Stephanie Stahl

PHILADELPHIA (CBS) — A summertime warning about pools, the water can be contaminated with a parasite, that’s resistant to chlorine.

It’s a summertime ritual, but a dip in the pool could also expose you to a nasty parasite that health officials say is spreading.  Danielle Uemah, a mom who owns a pool says, “That’s a little concerning um this is a new pool so we don’t want anybody to come and get sick.”

The bacteria, called cryptosporidium, comes from feces.  “It’s a common bacteria,” says Dr. Lawrence Livornese, the Chairman of Medicine with Main Line Health.   He says while it’s found everywhere, people are most often exposed in pools.

“This parasite is resistant to levels of chlorine we use in pools and filters don’t remove it either,” Dr. Livornese explains.

The Pennsylvania Health Department says the parasite caused 369 illnesses last year, not all from pool exposures.

In New Jersey there were 77 cases.

The CDC says the bacteria can cause gastro-intestinal symptoms and usually isn’t dangerous, except for children and people immune compromised. Dr. Livornese says, “You can’t see it this is a microscopic organism.”

Experts say showering before going in the pool will help keep the parasite from contaminating the water and rinsing off after, can guard against getting sick.

“We have a rule. Before you go in, everybody needs to take a shower. And we have an outside shower which is really convenient,” said Uemah.

The CDC says the parasite can live in water for 10 days or more, sometimes pools need to be closed and treated with an extra big dose of chlorine.

Stephanie Stahl