By Dennis Thompson
HealthDay Reporter
THURSDAY, May 18, 2017 (HealthDay News) — Families seeking to cool off don't should worry about catching a nasty infection. Yet outbreaks of a diarrhea-causing parasitic infection have doubled lately at swimming pools and water playgrounds across the United States, health officials warn.
According to a recent report from the U.S. Centers for Disease Control and Prevention, a minimum of 32 outbreaks of cryptosporidiosis were reported in 2016, in comparison with 16 outbreaks in 2014.
Crypto is probably the most common reason for diarrhea, based on the CDC. It spreads when people come into contact with the feces of an infected person.
Otherwise healthy people can suffer from watery diarrhea, stomach cramps, nausea or vomiting for up to a few weeks, the CDC warns. In individuals with weakened immune systems, the infection could be life-threatening.
The cause? Adults or children who've cryptodiarrhea swim in public pools despite their illness, thereby spreading the parasite, says Michele Hlavsa, director of the CDC's Healthy Swimming Program.
During a bout of diarrhea, “a typical person who is ill with Cryptosporidium can release 10 to 100 million oocysts, which is the infectious stage of crypto infection,” Hlavsa said. “Swallowing 10 or fewer of these oocysts can make you sick. If we look at a normal-sized pool, even swallowing a mouthful of water can make us sick.”
People can also contaminate swimming pool water with crypto through physical contact, says Lilly Kan, senior director of infectious diseases and informatics at the National Association of County & City Health Officials (NACCHO).
For example, parents could spread the parasite if they change a child's crypto-contaminated diaper and then jump into the water without washing their hands thoroughly, Kan said.
Hlavsa explained that Crypto is chlorine resistant and can even survive in sufficiently chlorinated pool water for up to 10 days.
“The oocysts have a hard outer shell and are therefore very resistant to chemical disinfectants,” said Hlavsa.
According to the CDC report, the variety of crypto outbreaks last 12 months was the very best in the last decade.
However, experts cannot say whether there are literally more outbreaks or whether health authorities are actually higher at detecting them, Hlavsa said.
The results were published in the CDC on May 19. Morbidity and Mortality Weekly Report (MMWR).
The report cited some state-specific outbreaks:
- Ohio saw a nearly fivefold increase in cryptosporidiosis cases in 2016, with 1,940 cases reported, compared to an average of 399 cases in the previous four years. In one outbreak, members of a university sports team became ill after visiting a water park.
- Arizona reported 352 laboratory-confirmed cases between July and October 2016, compared to a maximum of 62 cases per year in previous years. Among them were 36 players and family members of a Little League team who became ill after visiting a swimming facility in Maricopa County.
People who are sick with diarrhea should not go swimming and keep children with diarrhea away from swimming, Hlavsa said. If they have been diagnosed with crypto, they should wait two weeks after the diarrhea subsides before swimming.
Parents should take their children to the bathroom frequently and not rely on swim diapers to protect other swimmers from their child's diarrhea, Hlavsa added.
“Swim diapers don't contain diarrhea,” she said. “If water gets within the diaper, water will come out.”
To protect themselves, swimmers should avoid swallowing pool water and be certain children do not need pool toys that encourage swallowing, Hlavsa said.
A second report in MMWR identified one other potential danger of public swimming pools: inhaling toxic chlorine gas.
Between 2008 and 2015, about 190 people were injured in nine different cases in California as a consequence of improper handling of pool chemicals, the report said. Symptoms of inhaling chlorine gas included vomiting, coughing and eye irritation.
Workers must read pool chemical labels, follow directions and wear proper safety equipment, Hlavsa said.
In addition, Jennifer Li, senior director of environmental health at NACCHO, explained that employees should clear the pool area before starting circulation pumps since the introduction of concentrated pool chemicals could cause a sudden release of chlorine gas.
Operators of swimming pools and water parks must be sure that their employees are trained, Li added.
“There are a lot of seasonal staff in these public places, and they need to be thoroughly trained before they start doing pool maintenance there,” Li said.