Cryptosporidium and Giardia in Swimming Pools and Spa Pools

Cryptosporidium parvum is a parasitic protozoan micro-organism which causes an infection of the gastrointestinal tract called Cryptosporidiosis. Giardia lamblia is the main parasitic protozoan micro-organism which causes an infection of the upper gastrointestinal tract called Giardiasis. People who have had diarrhoea within the previous two weeks should not swim in any swimming pool or spa.

Last updated: 22 February 2010

Cryptosporidiosis

Cryptosporidium parvum is a parasitic protozoan micro-organism which causes an infection of the gastrointestinal tract called Cryptosporidiosis. Symptoms include anorexia, vomiting, cramping abdominal pain, profuse watery diarrhoea, and sometimes fever and depression. The symptoms may wax and wane over the period of infection which tends to be self-limited to about 30 days. The illness is more common in infants and children due to their lack of personal hygiene. Cryptosporidiosis could be a serious illness for those infected with HIV. There is no treatment for Cryptosporidiosis. Diagnosis is by isolation and microscopic identification of parasites or oocysts from faecal samples. The incubation period from ingestion to symptoms is up to 12 days but commonly 7 days. Asymptomatic carriers are common. Outbreaks tend to occur every few years.

The parasite invades and multiplies in the gastro-intestinal tract causing illness and producing oocysts. The oocysts are the infective form of the parasite and pass out in faeces to infect other individuals through direct contact or through ingesting faecally contaminated swimming pool water. Oocysts are chlorine and bromine resistant at normal pool operating concentrations.

Giardiasis

Giardia lamblia is the main parasitic protozoan micro-organism which causes an infection of the upper gastrointestinal tract called Giardiasis. Symptoms include abdominal cramps, chronic diarrhoea, bloating, fatigue and weight loss. Malabsorption of fats or fat soluble vitamins may occur. The illness is more common in infants and children due to their lack of personal hygiene. The incubation period from ingestion to symptoms is up to 25 days but commonly 7 to 10 days. Asymptomatic carrier rate is high. Anti-infective drug treatment is available.
The parasite invades and multiplies in the upper gastro-intestinal tract causing illness and producing cysts. The cysts are the infective form of the parasite and pass out in faeces to infect other individuals mainly through direct contact or through ingesting faecally contaminated swimming pool water. Oocysts are slightly chlorine and bromine resistant at normal pool operating concentrations.

Management

Management can be considered in three categories: hygiene, education and pool operations.

1. Hygiene

2. Education

Staff and swimmers should be educated in their responsibilities to minimise disease transmission. Additionally, staff have a "duty of care" to their swimmers. The following educational strategies are recommended:
• There are posters and pamphlets available for download from the Health Department's website dedicated to the "Health Swimming Campaign" at the NSW Health swimming pool website
• Provide suitable signs in the entry foyer, behind toilet doors, shower and hand washing areas about personal hygiene which include the points specified above
• Ensure that all staff are aware of procedures and protocols to be followed in case of an adverse event such as a faecal accident
• Ensure that patrons are aware that management has the right to prevent people with unsatisfactory hygiene practices from swimming/bathing i.e. nude bathing of infants

3. Pool operational management

• The toddlers pool should have its own circulation, filtration and disinfection system independent of other pools
• Circulation and filter systems should be operated at maximum efficiency before during and after swimming. Filtration must not be relied upon to control Cryptosporidium oocysts
• Chlorine pools should be operated to achieve breakpoint chlorination daily
• Disinfectant concentrations should always be maintained above minimum guideline values and in anticipation of peak loads
• pH should be maintained at optimum guideline values
• All pools should be regularly floor suctioned
• Fortnightly superchlorination to 10mg/L free chlorine should be considered during Cryptosporidiosis and Giardiasis outbreaks
• Strategies and protocols to recover from faecal accidents and vomiting in the pool should be prepared; see the Department's website below for suggested protocols
• Validate disinfection by routine bacteriological sampling and testing
• Strategies should be prepared in case the pool is epidemiologically linked to an outbreak where closure and specific disinfection will be required
• Where toddler learn to swim classes are conducted, make-up classes should be offered where a child has had diarrhoea in the previous two weeks. A disclosure form template and explanation is available in the Public Swimming Pool and Spa Pool Code of Practice (Chapter 8)

Further Information

Guidelines for Disinfecting Public Swimming Pools and Spa Pools specify the required disinfection concentrations and other chemical parameters for public swimming pools and spa pools operations.

Public Swimming Pool and Spa Pool Code of Practice provides detailed explanations and information on disinfection, pool chemistry, risk assessment and other issues relevant to swimming pool operation.

Both the Guidelines and Code of Practice may be found at the NSW Health swimming pool website