Illness From The Swimming Pool?

Author: Compiled From The CDC

As you know, this summer swimming pools will be filled with millions of people having fun and staying cool. But germs from swimmers can contaminate the water. In the past we weren't as concerned but today there are new germs that can contaminate water and cause illness. This summer, learning about recreational water illnesses (RWIs) will help decrease the chance of illness transmission at your venue.

Recreational water illnesses are caused by germs such as "Crypto" (KRIP-toe, short for Cryptosporidium), Giardia (gee-ARE-dee-uh), E. coli 0157:H7, and Shigella (Shi-GE-luh) and are spread by accidentally swallowing water that has been contaminated with fecal matter. People in the pool share the water with everyone else in the pool. If someone with diarrhea contaminates the water, swallowing the water can make people sick.

The great news is that germs causing RWIs are killed by the chlorine you have in your pool. However, chlorine doesn't work right away. It takes time to kill germs and some germs like Crypto are resistant to chlorine and can live in pools for days. That is why even the best maintained pools can spread illness. Therefore, the promotion of healthy swimming behaviors is essential for any recreational water venue. Healthy swimming behaviors can protect patrons and their children from RWIs and will help stop germs from getting in the pool in the first place

How can swimming transmit illness?
Swimming is second to walking as the most popular exercise in the United States with more than 368 million annual visits to swimming pools. When people swim in pools, waterparks, spas, hot tubs, lakes, rivers, and the ocean, they share the same water. If someone is ill, he or she can contaminate the water for everyone who is swimming. Contaminated recreational water can cause a variety of illnesses such as diarrhea or skin, ear, eye, and upper respiratory infections. Kids who wear diapers are just learning to control their bowels and are more prone to contaminate the water. These young kids are more likely to have fecal accidents and, if they are ill with diarrhea, the germs in their stool can contaminate the pool. Once the pool is contaminated, patrons may accidentally swallow the fecally contaminated water, which could make them ill. In addition, some germs such as Crypto (short for Cryptosporidium) may take days to be killed by chlorine, increasing the risk of spreading illness.

Why should pool owners and staff think about illnesses spread through the water?
The Centers for Disease Control and Prevention (CDC) has been gathering information from State health authorities on recreational water illness (RWI) outbreaks in the United States since 1978. Diarrhea, which is currently the most frequently reported symptom, is caused by germs such as Crypto (short for Cryptosporidium), E. coli O157:H7 (E. coli), Giardia, and Shigella. Since 1985, the number of outbreaks of diarrhea connected with swimming pools is on the increase. Some of these outbreaks have affected thousands of swimmers. Much of the diarrheal illness reported to health officials, such as that caused by Crypto, happens during the summer swim season. CDC information from the past few years shows that Crypto is the major germ that causes outbreaks in swimming pools and waterparks, where its high chlorine resistance and small size make it a difficult problem for even the best-equipped and well-maintained pools. E. coli is sensitive to chlorine so most outbreaks have occurred in locations where no chlorine is added, such as lakes. E. coli outbreaks appear to be a rare occurrence in chlorinated pools with only two having been reported.

Approximately 10 diarrheal outbreaks linked to swimming pools are reported each year. However, pool staff need to keep in mind that most diarrheal illnesses are not reported to health care providers and health officials. This means that the number of outbreaks reported is probably only the tip of the iceberg. Because fewer than 10% of people with diarrhea ever go to see a health care provider, public health officials never hear about most cases of illness. Therefore, illness prevention should be a part of every swimming safety program just like the prevention of drowning, injuries, and sunburn.

Even though small or home pool staff may have fewer people swimming in their pools, they still need to be concerned about RWIs spread through pool water. Poor maintenance of the pool and the lack of healthy swimming behaviors may lead to low chlorine levels, clogged filters, and contamination of pool water, which may place swimmers at risk for diarrheal illnesses and skin, ear, eye, and upper respiratory infections. For more detailed information on specific germs spread through water visit: parasiticpathways/ swimming_diseases_spread.htm

Why is diarrhea in the pool a problem?
For any public swimming facility (remember everyone who is swimming shares the same pool water), continuous filtration and disinfection of water should reduce the risk of illness transmission. However, patrons may still be exposed to germs during the time it takes for chlorine to work or water to be recycled through filters. Most diarrheal outbreaks in pools appear to be related to fecal contamination of the water by someone who is ill with diarrhea. In addition, tiny amounts of fecal matter also rinse off all swimmers' bottoms as they swim through the water. Infectious diarrhea can contain hundreds of millions of germs in a single fecal accident. Many pools use one filtration system for several pools. This causes water from many pools to mix quickly, and distribute germs throughout connected pools in a very short amount of time. If other patrons then swallow the contaminated water, they may become infected and develop diarrhea or other illnesses. Since many illnesses can be spread by swallowing just a few germs, it is possible that a single diarrheal accident can contaminate water throughout the largest pool or waterpark. Therefore, isolating the filtration for your "kiddie" pool water from other pools to avoid cross-contamination is a good policy.

What is the difference between maintaining disinfectant in hot tubs/spas and maintaining disinfectant in swimming pools?
Skin infections are the most common infections spread through hot tubs and spas. The increased temperature of the water in hot tubs and spas can cause the chlorine to evaporate more rapidly than in swimming pools. As a result, chlorine or other disinfectant levels in hot tubs and spas need to be checked and adjusted more regularly than in swimming pools. Skin infections should not be transmitted if the water quality is appropriately maintained and monitored.

How severe can these illnesses be?
Diarrhea can be caused by many different germs. It can last from a few days to weeks. Pool patrons may not associate their diarrhea with swimming pools because illness may not occur until several days to weeks after swallowing contaminated water. Crypto (short for Cryptosporidium), a germ which causes diarrhea, cannot be treated and can be quite severe, resulting in emergency room or hospital visits for young children and pregnant women who can easily become dehydrated.

Crypto can be life-threatening and sometimes fatal in persons with compromised immune systems (such as persons living with AIDS , those who have received an organ transplant, or those receiving certain types of chemotherapy). Persons living with compromised immune systems should be aware that some swimming pools, waterparks, hot tubs, spas, ornamental water fountains, lakes, rivers, and salt-water beaches might be contaminated with human or animal waste that contains Crypto. To reduce the risk of illness, persons with compromised immune systems should avoid swimming in water that is likely to be contaminated and should avoid swallowing water while swimming or playing in recreational water.

For further information about Cryptosporidium go to: parasites/cryptosporidiosis/factsht_crypto_prevent_ci.htm

1999 USPHS/IDSA Guidelines for Prevention of Opportunistic Infections in Persons with Human Immunodeficiency Virus.

E. coli 0157:H7 infection can cause severe illness. The 1998 waterpark outbreak of E. coli 0157:H7 resulted in seven children having kidney failure, and one death. Outbreaks caused by E. coli O157:H7 appear to be rare in pools if free chlorine levels are maintained at regulated levels.

Are there germs that are chlorine resistant?
Yes. Fortunately, free chlorine at neutral pH kills most bacteria such as E. coli 0157:H7 in less than a minute if the free available chlorine is maintained at proper disinfection levels throughout the pool. However, a few germs are moderately (Giardia, Hepatitis A) to highly (Crypto, short for Cryptosporidium) chlorine-resistant. The table below shows the approximate disinfection times for these germs in chlorinated water. Many discussions have revolved around "how" resistant each of these germs is and whether the laboratory experiments represent swimming pool conditions. Current recommendations are based on the best and most reproducible laboratory information available.

In Conclusion...
In conclusion, healthy swimming is an "All-American" activity. Most people who swim don't get sick or injured. Although the risk of RWI outbreaks is probably low, current risk management practices suggest that planning for low-risk events (such as drowning, lightning strikes, etc.) is necessary and in everyone's best interest. .