2023-08-03 08:25:43
In the United States, between 2015 and 2019, more than 3,600 people became ill from bathing in poorly disinfected water in swimming pools, hot tubs, and water parks. About 0.14 grams of fecal matter is enough, an amount similar to a few grains of sand, to contaminate a swimming pool.
The arrival of heat causes massive transhumance to swimming pools and aquatic leisure centers. Ignoring, perhaps, that recreational activities in swimming pools, spas, jacuzzis, lakes, rivers, or oceans expose us to contracting various infectious diseases, which generally affect the digestive system, skin, or respiratory system.
In Spain alone there are more than 1.2 million private swimming pools for single-family use or enjoyed by a community of owners whose waters must be monitored to prevent the proliferation of pathogenic microorganisms. A figure to which must be added more than 70,000 swimming pools for public use.
The pathogenic organisms that we can find in recreational waters are diverse: pseudomonas, protozoa, staphylococci, fecal streptococci, fecal coliforms such as the famous Escherichia coli, total coliforms, norovirus or even legionella, which usually appears in heated pools or spas.
There is no global data for Spain, but in the United States, between 2015 and 2019, more than 3,600 people fell ill from bathing in poorly disinfected water in swimming pools, jacuzzis, and water parks. There were 286 hospitalizations and thirteen people died.
Feces in more than half of the pools
Specifically, the presence of Escherichia coli is a specific indicator of aquatic fecal contamination and its detection leads to the immediate closure of the pool to disinfect the water.
About 0.14 grams of fecal matter is enough, an amount similar to a few grains of sand, to contaminate a swimming pool. That is why sick people with diarrhea should not bathe.
A study conducted in public pools in the United States during the summer swimming season confirmed that swimmers frequently introduce feces into the pool water. Specifically, the analysis found that 58% of the pool filter samples tested tested positive for Escherichia coli.
swimmer’s ear
The same study detected Pseudomonas aeruginosa in 59% of the samples. According to technical-sanitary criteria, the limit presence for this bacterium in swimming pool water is zero colony-forming units per 100 milliliters of water.
Pseudomonas aeruginosa poses a serious public health problem, because it can cause two infections that are commonly known as bathtub folliculitis and swimmer’s ear.
Symptoms of the former include rashes and reddish bumps on the skin that are very itchy, as well as pus-filled blisters around hair follicles. Swimmer’s ear sufferers experience itching, pus, and pain in the infected ear.
The bacterium Pseudomonas aeruginosa can also cause infections in the cornea or in the urinary and respiratory tracts. Even, occasionally, headaches and muscles, burning eyes and fever.
Colic and diarrhea
Giardia duodenalis and Cryptosporidium are ubiquitous intestinal protozoa parasitizing domestic and wild animals, but also humans.
They are the main responsible for most of the gastrointestinal diseases transmitted by contaminated water and food worldwide. Both cause attacks of watery diarrhea, accompanied by colic in the case of Giardia.
Contaminated drinking and recreational waters account for the majority of exposure to Cryptosporidium spp. in high-income countries. Cases in Europe and the United States are frequent each year.
In the United States, in the period 2015-2019, Cryptosporidium caused 76 outbreaks from bathing in poorly disinfected water in swimming pools, hot tubs, and water parks, resulting in 2,492 cases. The most important outbreaks occurred in 1993 in Milwaukee (USA), with 400,000 cases, and in 2010 in Sweden, with 27,000 cases.
The disinfecting action of chlorine
Chlorine is the most common disinfectant used in swimming pool water. It kills bacteria by attacking the lipids in cell walls and destroying enzymes and structures within the cell.
The chlorine that remains in the water after killing the entire microbial community is called residual free chlorine. Its values must be between 0.5 and 2 milligrams per liter, because the absence of chlorine or exceeding that limit leads to the closure of the pool.
The cause of eye irritation and bad odors in the water is residual combined chlorine, which results from the combination of free chlorine with other non-pathogenic substances present in the water.
The pH level is also regularly measured, which should be maintained at approximately values between 7.2 and 7.8.
If the pH is acid (values below 7) bathers may suffer damage to the mucous membranes, eyes, skin, etc. and the elements and materials that make up the pool deteriorate more quickly.
On the contrary, if the pH is excessively basic (values above 8), the disinfectant will not work effectively, and users may suffer skin problems and algae and microorganisms will proliferate rapidly in the water, which may take on greenish tones.
Baths in rivers and lakes
The recent detection of Cryptosporidium hominis and other cryptosporidian species in Galician wild foxes may indicate the probable overlap of the sylvatic and domestic cycles of this parasite in rural environments. And if there is active transmission between farm animals and wild animals, the possibility of transmission to humans opens up.
That is one of the reasons why it is not advisable to bathe in natural areas, such as rivers, lakes or uncontrolled streams. In the same way, it is dangerous for pets to swim in water where there is a proliferation of microalgae, diatoms, cyanobacteria or dinoflagellates, because they can be intoxicated. The massive presence of these organisms can turn the water green or blue-green, and even with orange/red or yellow/brown tones. The potential toxins produced by marine dinoflagellates alone cause more than 60,000 poisoning incidents per year, with a mortality rate of 1.5% worldwide. M.T.T. (SyM)
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