Cryptosporidium and Cryptosporidiosis - Information for swimming pool managers

Information for managers and operators of swimming pools about the risks of cryptosporidiosis and ways to help prevent it. This is based on a similar fact sheet from Centers for Disease Control USA.

What is Cryptosporidum and cryptosporidiosis?

How easy is it to become infected with Cryptosporidium?

Fairly easily. The number of Cryptosporidium oocysts needed to cause infection is probably very low; as few as 2-10 oocysts have been shown to cause illness in animals.

When someone is infected, how contagious is their infection? For what period of time can they transmit the disease?

At the height of infection a person is very contagious and may pass millions of infectious oocysts per day in their faeces, enough to contaminate a large pool. Cryptosporidium oocysts appear in the faeces of infected persons at the onset of symptoms and can continue to be excreted for several weeks after the symptoms resolve. Outside the body, oocysts may remain infectious for 2-6 months in a moist environment. The ability of Cryptosporidium to infect the body is probably the same for everyone. However, the severity of disease differs and may be greater in children, pregnant women, and those whose immune systems are compromised.

Why is Cryptosporidium a problem for swimming pool operators?

Cryptosporidium is highly resistant to halogen (chlorine/bromine) disinfection. This is a concern in pools where the primary protection against disease transmission is halogen disinfection. Cryptosporidium oocysts, because they are microscopic, may pass through many types of pool sand filters and most cartridge filters. A diatomaceous earth filter can capture most of the oocysts. However, even with an effective filter it may take as long as 2 days to remove most of the oocysts from a pool (assuming a 6-hour turnover). More studies need to be undertaken before the effectiveness of nonhalogen liquid sanitisers and other methods of disinfection on Cryptosporidium are known. Additionally, new filter media and flocculants have not been studied to determine their effectiveness in removing Cryptosporidium oocysts.

Once a pool is contaminated (for example, through a faecal accident or by rinsing a nappy in the pool), it can remain a source of infection for pool users for prolonged periods of time because of Cryptosporidium's resistance to halogens and the difficulty of removing oocysts by filtration. Pool operators can reduce the risk of initial contamination by using common sense operating practices.

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What are some steps I can take to reduce the likelihood that my pool will be contaminated with Cryptosporidium?

Prepare a plan. In the event that you get calls about cryptosporidiosis, how would you answer questions and complaints? To whom would you refer these individuals? How would you manage press inquiries in the event of an outbreak?

• Prepare and implement a written faecal accident policy for your pool. Teach this policy to all relevant employees. Be sure that employees enforce your policy. Instruct pool attendants and other personnel to monitor the pool area for faecal accidents and behaviour that can put others at risk (e.g., rinsing a child's soiled bottom in a pool).
  

• Unfortunately, faecal accidents that are caused by Cryptosporidium infection are likely to be in the form of watery diarrhoea, and therefore will probably not be seen or reported. It is therefore important to:
  

  • Train staff (lifeguards or instructors) to report illnesses they experience to the management and not to swim if they are ill with diarrhoea or abdominal cramps.

  • Develop a policy for pool usage by nappy-aged and toddler children. These children are at high risk for having faecal accidents in the pool.
    

• The best situation is one where there is a separate pool for nappy-aged children that has a separate water circulation and filtration system. In such a situation, nappy-aged children should only be allowed in the pool specifically designated for them. Older children, adolescents, and adults should not be allowed in that pool unless they are caring for a nappy-aged child. After using the "toddler" pool, patrons should rinse off before entering the pool designated for older individuals. If a separate "toddler" pool is not possible, strong consideration should be given to excluding nappy-aged children from the pool. The use of rubber pants or "swim nappies" has been suggested as a way to reduce faecal contamination by infants and toddlers, but these methods have not been tested to determine their ability to contain Cryptosporidium.

• Encourage pre-swim showers.  Showering is important as thousands of oocysts may reside on the surfaces of the bottom after an infected person goes to the toilet. The oocysts can contaminate the pool upon contact with the water.
  

• Provide signage in a conspicuous location before pool entry. The sign might state:
  

  • "If you have or have had "gastro" or diarrhoea, please do not use the pool until after symptoms cease."
    "Shower your child and yourself before entering the pool."

• Maintain the recirculation and filtration equipment to provide maximum filtration. Many pools are periodically overused, and the average bather loads exceeded. These pools may need filtration equipment that exceeds required minimums just to maintain normal water quality during peak periods of use.
  

• Maintain the water quality in accordance with Part 7 of the Health (Infectious Diseases) Regulations 2001. This includes maintaining the disinfectant levels; optimal pH (7.2-8.0); and alkalinity (greater than 60 mg/L). Lack of proper pH can greatly affect disinfection effectiveness in chlorinated pools. Although cryptosporidiosis is chlorine resistant, maintaining proper equipment and chemical levels will reduce the risk of illness from most other faecally transmitted pathogens. Consider scheduling pool usage by incontinent persons (e.g. infant swim classes) later in the day to allow for filtration systems to run overnight before heavy usage by other patrons.
  

• Provide training on the prevention of diseases and injuries for all persons responsible for the maintenance and operation of the swimming pool. Include in this training information regarding Cryptosporidium.
  

• Provide safe and easily accessed nappy-changing areas and discourage nappy-changing at poolside. Inspect your facility often.
  

• Use club or organisation newsletters to remind patrons:

  • Toddlers should wear close fitting swimsuits or underwear in order to better contain solid or semi-solid faeces.
  • Do not drink pool water.
  • Do not use the pool if you or your child has had diarrhoea in the previous week.
  • Do not change your child's nappy at poolside.
  • Do not rinse nappy-aged children in the pool before, during, or after nappy changes.
  • Assist young children in making frequent visits to the bathroom to minimise accidents.
  • Do not rinse hands in the pool following a trip to the bathroom or changing a child's nappy. Wash hands correctly by using soap and warm water and thoroughly cleaning all hand surfaces.
  • Notify the pool management if you or a family member develops a gastrointestinal illness that you think may have been related to a visit to the swimming pool.

Following these recommendations may help reduce the risk of Cryptosporidium contamination of your pool.

What should I do if the Department advises that there is a general increase in the number of cases of Cryptosporidium?

• Inform patrons and staff about the increase of cases of Cryptosporidium.

• Recommend that patrons or staff do not swim for 2 weeks after diarrhoea has ceased.

• Inspect your pool filtration to confirm it is working.

• Review your faecal accident policy if you have one.  If you don’t have a policy, we strongly recommend you develop one.

What can I do if cases of Cryptosporidium infection are linked to my facility?

The Department of Human Services considers cases to be linked to a facility if two or more people with Cryptosporidium infection (confirmed by a pathology laboratory) have used the same pool within the two weeks of their illness. In addition to the steps listed above, you may need to:

• close the affected swimming pools until they have been treated, and

• superchlorinate the affected pools with at least 14 mg/L free chlorine for at least 12 hours.

It is important to ensure that the total chlorine level in a treated pool is less than 8 mg/L, as specified in the "Health (Infectious Diseases) Regulations 2001", before re-opening. If an outbreak is particularly large, the Department may request additional steps to be undertaken.

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