Swimming pools, hot tubs are more likely than lakes to make you sick, studies find

July 9, 2018 by Glenn Howatt, Star Tribune (Minneapolis)
Credit: CC0 Public Domain

Taking a cool, refreshing dip in a lake or swimming pool is one of summer's enjoyments and sometimes a necessary escape from the stifling heat.

But two recent federal health studies found that some waters is better than others, at least when it comes to avoiding waterborne illnesses.

Of 633 outbreaks nationwide caused by bacteria, viruses or other things floating around, nearly 80 percent of them were traced to that was treated with chlorine or other chemicals in swimming pools, hot tubs or wading pools. Most illnesses cause intestinal problems and diarrhea.

The studies, which tracked outbreaks from 2000 through 2014, found 493 outbreaks where 27,219 people were sickened and eight died from pathogens in recreational water treated with chemicals. The figures do not include sicknesses linked to private pools or cases where just one person got ill.

By comparison, there were just 140 outbreaks linked to lakes, rivers or swimming holes, with 4,958 people falling ill and two deaths, according to the Centers for Disease Control and Prevention.

"People have a false sense of security when they go to a ," said Trisha Robinson, an epidemiologist supervisor at the Minnesota Department of Health. "There is this sense that chlorine kills everything. That is not the case."

In Minnesota, there were 51 reported recreational-water disease outbreaks over the past 10 years. Only nine were from pathogens in lakes or rivers. Still, compared with , which recently have been linked to tainted lettuce, pre-cut melon, raw veggie plates, cereal, eggs and restaurant workers who don't wash their hands, the risk of getting a waterborne illness is relatively low.

In Minnesota, must be licensed and often are inspected annually. Regulators check on safety equipment, plumbing and chemical levels.

"If they are not meeting the chlorine level, we would do a closure on that until they meet the requirement," said Ryan Krick, an environment health supervisor at the Minneapolis Department of Health.

Pool operators are also required to check chemical levels daily and keep a log of chemicals added.

But add people to the , and that is where the problems begin.

"It really is a communal bathtub," said Robinson. "You are sharing water and germs in it with everybody else that is in there."

The chlorine and other chemicals help neutralize some things, but many outbreaks have been caused by Cryptosporidium, a tiny parasite that can survive in chlorinated water up to seven days.

The source of the problem is human fecal matter. While an accident made by an infant is the nightmare scenario, even the most fastidious adults can be the source if they do not shower before entering the pool.

"We can make a lot of people sick if we don't take precautions," said Robinson.

No one who has not showered should swim in a lake either, but the sheer size of most lakes means the bacteria and microscopic parasites disperse, lessening the chances of infection even if someone swallows water accidentally.

Most of the waterborne diseases lead to stomach and intestinal symptoms, including diarrhea, stomach cramps, fever, and vomiting.

Tragically, Minnesota has seen two fatalities in children caused from a waterborne amoeba that enters the nose and attacks the brain. Although rare, it is most risky in shallow, warm lakewater. Parents should teach children to try to keep water out of their noses or mouths, Robinson said.

Also, people should avoid swimming in areas that are contaminated with animal feces. Some local and state health departments monitor beaches for contamination.

"Swimming is a really great activity," said Robinson. "No matter where (you are) swimming, try not to swallow the water."

Explore further: July is peak time for illness from poop in pools: CDC


Related Stories

July is peak time for illness from poop in pools: CDC

June 28, 2018
(HealthDay)—Is it safe to go in the water this summer? Not if microscopic germs like E. coli or cryptosporidium are swimming in the pool with you, U.S. health officials warn.

Yes, you can put too much chlorine in a pool

June 2, 2018
(HealthDay)—Before you take a dip in the pool this summer, be sure there's not too much chlorine in the water.

The water's not fine: U.S. pool-linked infection doubles in two years

May 18, 2017
(HealthDay)—Families seeking to cool off don't expect to pick up a nasty infection. Yet, outbreaks of a diarrhea-causing parasitic infection have doubled in recent years at swimming pools and water playgrounds in the United ...

Study highlights risk of norovirus from swimming

May 15, 2015
Simple tips can help swimmers stay safe in various swimming venues.

CDC IDs outbreak trends tied to treated recreational water

May 26, 2018
(HealthDay)—Outbreaks associated with treated recreational water with confirmed infectious etiology are usually caused by Cryptosporidium, Legionella, or Pseudomonas, according to research published in the May 18 issue ...

Outbreaks linked to drinking water mainly due to Legionella

November 14, 2017
(HealthDay)—Most drinking water-associated waterborne disease outbreaks and waterborne disease outbreaks associated with environmental or undetermined exposure to water are due to Legionella, according to two studies published ...

Recommended for you

Crunched for time? High-intensity exercise = same cell benefits in fewer minutes

September 20, 2018
A few minutes of high-intensity interval or sprinting exercise may be as effective as much longer exercise sessions in spurring beneficial improvements in mitochondrial function, according to new research. The small study ...

China's doctor shortage prompts rush for AI health care

September 20, 2018
Qu Jianguo, 64, had a futuristic medical visit in Shanghai as he put his wrist through an automated pulse-taking machine and received the result within two minutes on a mobile phone—without a doctor present.

Time to ban the sale of energy drinks to children, says senior doctor

September 19, 2018
It's time to bring in laws to ban the sale of caffeinated energy drinks to children and young people in England to tackle the twin epidemics of obesity and mental health problems, argues Professor Russell Viner, President ...

For-profit hospitals correlated with higher readmission rates

September 19, 2018
Patients who receive care in a for-profit hospital are more likely to be readmitted than those who receive care in nonprofit or public hospitals, according to a new study published by University of Illinois at Chicago researchers.

Sugar content of most supermarket yogurts well above recommended threshold

September 18, 2018
A comprehensive survey of ingredients in yogurts highlights high sugar levels in many—particularly organic yogurts and those marketed towards children.

Research confronts 'yucky' attitudes about genetically engineered foods

September 18, 2018
Is a non-browning apple less "natural" than non-fat milk? In one case, people have injected something into apple DNA to prevent it from turning brown after it's cut. In the other, people used technology to remove something ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.