Pseudomonas, Cryptosporidium, Legionella… What Germs Should You Worry About in Pools and Spas?

by | Sep 15, 2024 | Learn, Legionella, Sanitary Water

Pseudomonas, Cryptosporidium, Legionella… What Germs Should You Worry About in Pools and Spas?

Published on Sep 15, 2024
A laboratory technician is checking the quality control of its orange juice

The main diseases contracted in pools and spas are caused by about ten pathogenic organisms, including Cryptosporidium, Pseudomonas, Shigella, Legionella, Norovirus, and Escherichia coli.

Several Microorganisms Cause Gastrointestinal Illnesses in Pools

The ubiquitous presence of Cryptosporidium in pools is explained by the strong chlorine resistance granted by its protective shell.

This parasite can survive for up to 7 days in chlorinated pool water (minimum 1 ppm chlorine, in accordance with national health guidelines in the United States and France). It can also cause diarrhea and all the symptoms typically associated with it (headaches, dehydration…).

The Norovirus and the bacterium Shigella induce acute gastroenteritis.

Certain virulent strains of E. coli are also responsible for the occurrence of gastroenteritis, but also urinary infections, meningitis, or sepsis.

Pseudomonas aeruginosa and Legionella pneumophila Are Common in Hot Water

Among other infections, Pseudomonas aeruginosa is generally not very dangerous except in immunocompromised patients. In such cases, it can cause various urinary, skin, pulmonary, and ophthalmological infections…

Legionella, particularly Legionella pneumophila, is responsible for ailments like Pontiac fever. However, it can also lead to a fatal pneumonia : Legionnaire’s disease. It particularly affects immunocompromised patients, the elderly, and young children.

Thus, according to an American study based on 493 pools between 2000 and 2014, 6 of the 8 deaths recorded from the 27,219 pool-related infections were attributable to Legionella.

What Individual Precautions Can Reduce the Risk of Infection?

A number of recommendations can be applied at the individual level to avoid risks, such as:

  • Do not swallow pool water.
  • Do not go to the pool if you have diarrhea.
  • Check chlorine levels yourself using test strips.
  • Avoid overcrowded pools.

Additionally, public pool managers must ensure that the levels of treatment products (chlorine, bromine…) are always above a certain threshold.

They must conduct water tests several times a day to detect any unusual concentrations of pathogenic microorganisms.

In addition to the germs mentioned earlier, staphylococci, mycobacteria, and pathogenic amoebae must be monitored in the water.

Continuous treatments are not sufficient to eradicate all germs from pools. However, awareness of good practices has helped stop the spread of infections caused by Cryptosporidium.

Increased Risk of Legionella in Hot Tubs and Spas, Especially in Hotels

The constant agitation and high temperature of hot tubs allow bacteria to survive. It can also lead to the evaporation of some disinfectant.

Moreover, the more frequented the baths are, the more organic matter such as sweat, dead skin, or urine is introduced, exceeding the treatment’s neutralizing capacity.

Bubbles generate aerosols, and if the water is infected with a large number of Legionella, contamination through inhalation becomes possible.

Many hotels have pools and hot tubs and are characterized by high peaks of attendance, especiallyin summer.

Thus, a 2018 European study conducted on 1,079 cases of legionellosis occurring in spas showed that 10 out of 22 epidemic clusters originated from a hotel establishment.

Specifics of Regulations Regarding Legionella Monitoring

Beyond the pool water, major risk points for Legionella proliferation in pools are located at showers and hot tubs.

Facility managers play a significant preventive role in this regard. They must ensure that the concentration of Legionella in the hot water supply networks does not exceed 1,000 CFU/L at any point in the network.

Additionally, it is necessary to carry out regular water sampling and ensure that hot water exceeds 50°C in the hot water network to prevent Legionella proliferation.

Serious Consequences for Establishments in Case of a Positive Inspection

The law provides for penalties in case of negligence in managing the risk, and the establishment can be closed if a positive inspection occurs.

For example, the Cergy-Pontoise agglomeration decided to close the Ravinière pool in Osny and the Louvrais pool in Pontoise in May 2019 alone.

In early July, the Saint-Cyr-sur-Loire pool had to suspend access.

The Closeaux pool in Rueil-Malmaison is being targeted by a complaint for concealing results that exceeded regulatory thresholds and remaining open in 2018.

The Resistance of Legionella Requires Regular Monitoring Through Self-Control Tests

Legionella is today the most concerning germ in pools and spas and it is difficult to eliminate it definitively.

A 2019 European study based on 357 hotel establishments that implemented corrective measures following a positive inspection showed that 25% of them experienced at least one new case of legionellosis in the following two years.

42% of these resurgence cases concerned Italy, 17% Spain, 14% France, and 7.6% Greece.

Compliance with regulatory obligations is not sufficient to contain the risk of Legionella contamination.

Fortunately, advances in preventive controls exist.

Detection kits usable by any facility manager allow optimal responsiveness to adjust treatment based on the actual concentration of Legionella in the water networks.

They also offer the possibility to monitor the evolution of the bacteria in the networks over several years, enabling action at the first signs of network colonization.

 

Sources:

[1] Hlavsa MC, Cikesh BL, Roberts VA, et al. Outbreaks Associated with Treated Recreational Water — United States, 2000–2014. MMWR Morb Mortal Wkly Rep 2018;67:547–551. DOI: http://dx.doi.org/10.15585/mmwr.mm6719a3

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