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There was a total of 493 outbreaks associated with treated recreational water in 46 states and Puerto Rico from 2000 to 2014, according to a United States Centers for Disease Control and Prevention (CDC) report.
The report defines an outbreak as similar illnesses occurring in two or more people that are linked by location and time to a particular body of treated water.
These outbreaks resulted in at least 27,219 cases and eight deaths during the 15-year period.
Hotels were the leading setting, associated with 32 percent of outbreaks.
Hot tubs were associated with 41 percent of hotel-related outbreaks.
Approximately 20 percent of the 13,864 routine inspections of public hot tubs conducted in 16 jurisdictions in 2013 identified improper disinfectant concentrations, the CDC reports.
Hot tubs require different maintenance because the water is typically warmer, according to Michele Hlavsa, lead author of the report and chief of the CDC's Healthy Swimming Program.
The warmer water increases the multiplying or the dividing of bacteria. It also makes it harder to maintain the chlorine or bromine level. It burns through chlorine much faster.
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“When you have higher temperatures, it's harder to maintain that chlorine level, as opposed to a cooler pool,” Hlavsa said.
More than half, 56 percent, of all outbreaks happened during summer months, from June through August. A second peak occurred in March with 9 percent of outbreaks, the CDC reports.
When the sun heats the water, germs can flourish. The peak also coincides with the summer swim season.
Among the 493 outbreaks, 94 percent were caused by pathogens and resulted in at least 24,453 cases.
Only 6 percent of outbreaks were caused by chemicals and resulted in at least 1,028 cases.
Among the pathogen outbreaks, 58 percent were caused by Cryptosporidium, 16 percent were caused by Legionella and 3 percent by Pseudomonas.
Whereas, of the 24,453 individual pathogen cases, 89 percent of cases were caused by Cryptosporidium, and only 4 percent of cases were caused by Pseudomonas and 3 percent by Legionella.
At least six of the eight deaths could be attributed to Legionella, which causes Legionnaires' disease, a severe pneumonia and Pontiac fever, a milder flu-like illness.
Pseudomonas causes “hot tub rash” and “swimmers’ ear.”
Legionella and Pseudomonas are effectively controlled by halogens like chlorine and bromine in well-maintained treated venues.
"Chlorine is the primary barrier to the transmission of pathogens in treated recreational water. At CDC-recommended concentrations of at least 1PPM, free available chlorine inactivates most pathogens within minutes," the CDC report reads.
However, Cryptosporidium, commonly known as Crypto, can survive even in well-maintained pools and can give swimmers gastrointestinal illness and diarrhea.
Extremely chlorine-tolerant Crypto can survive for over seven days.
The parasite’s extreme chlorine tolerance enables it to persist in water, cause outbreaks that sicken thousands and spread to multiple recreational water venues and other settings, according to the report.
The parasite is transmitted when a diarrheal incident, a high-risk Cryptosporidium contamination event, occurs in the water and the contaminated water is ingested.
The report highlights the importance of pool maintenance.
There is more to maintaining a pool than simply throwing chlorine into the pool. It's about working on the pH. The pH level determines how well the chlorine, or the bromine, can kill germs in the water.
"We need to make sure that the operators are trained appropriately, that they successfully completed a training course approved by the health department or that they are someone that a trained operator has trained," Hlavsa said.
The operator should be able to test the chlorine level, test the pH, adjust the water chemistry as needed and close the facility if it poses a threat to public health.
“This is by no means a message about not swimming; this is a message about swimming healthier and safer,” Hlavsa said.
Hlavsa provided numerous tips on how to swim healthier this summer:
Do not swim ill
Do not swim while ill or sick with diarrhea.
"Do not let your kids swim ill with diarrhea because you're potentially introducing Cryptosporidium into the water, and we don't want to bring Cryptosporidium in the water because once it is the water, it’s hard to get out," Hlavsa said.
Check the pool inspection scores
"Before we go out to eat, we check inspection scores. Before we jump into the water of our public pools, we should be checking the inspection scores," Hlavsa said.
Public pools are not your or your neighbor's backyard pools, but pools where you expect more than one family to be using, such as water parks, town pools or a hotel pool.
"You can do it online on the state or local health departments website or you can do it at the waterside. Some places require facilities to post their score at the waterside or at the entrance much like at a restaurant," Hlavsa said.
Conduct your own mini inspections
Test strips are available at your big box stores, your hardware supply stores or your pool supplies stores. You can get about 100 of them for around $10, according to Hlavsa.
"You can’t so much do it for cryptosporidium. But for Legionella, for Pseudomonas and for other germs, use test strips to check that chlorine or bromine level and to check the pH," Hlavsa said.
Don't swallow the water
"Bromine and chlorine kill most germs within minutes but clearly not instantly. And in the case of Cryptosporidium, not for days. So you don’t want to be drinking the water you’re swimming in," Hlavsa said.
Avoid hot tubs or spas if you are at increased risk
If you are at increased risk for becoming sick, avoid hot tubs and the vicinity of hot tubs.
Legionella can be spread through hot tub jets, which spray water out into the air like mists and aerosols.
"The aerosols containing these germs are inhaled. So, it's about not being around the hot tub at all," Hlavsa said.
For more safety and preparedness tips, visit AccuWeather.com/Ready.
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