Swimming pools vs. wild swimming: which is worse for germs?

There are also natural hazards to outdoor waters compared with pools, especially in the summer. Blue–green algae is a type of bacteria naturally found in lake ecosystems. In warm summers, the algae tends to multiply and form a powdery green scum (known as a bloom) on the surface of the lake. This blue-green algae bloom can release toxins which are harmful to humans and occasionally lethal to pets.
Swimming in or swallowing water containing toxin-releasing algal blooms can lead to skin rashes, eye irritation, severe gastrointestinal upset, fever, and muscle and joint pain.

Bacteria and viruses

Diarrhoea is the most common illness linked to open-water swimming, often due to sewage contamination. You become ill if you swallow contaminated water, which can contain bacteria and viruses such as E.coli and Norovirus.

Rats living in sewers adjacent to freshwater rivers or canals can also carry in their urine the bacterial pathogen Leptospira, which causes Leptospirosis (Weil’s disease). The infection occurs if soil or water from a lake, river or canal that contains urine from infected animals is swallowed, gets in a swimmer’s eyes or a cut.

Leptospirosis can cause liver and kidney damage, and may be fatal if left untreated. If you develop flu or jaundice symptoms up to two weeks after swimming in a river or canal, it may be a good idea to ask your doctor for a Leptospirosis test.

As for the sea, a 2018 study found that people swimming in seawater were more likely to experience infections of the ear, nose, throat and gastrointestinal system than those who stayed on the beach. So it’s a good idea to wash after swimming in any outdoor waters, and certainly before eating food.

The verdict

When you add it all up, even with the possibility of people peeing and pooping in the pool, a managed swimming pool will always be a safer environment for a swim. Especially when you consider things like jellyfish stings and the additional risks that come with swimming in cold water.

Compared with a pool, wild swimmers are more likely to become unwell from swimming in outdoor water as there will always be potentially disease-causing microbes present.

Swimming pool water, with adequate chlorine disinfection levels and pH maintenance, is much less likely to contain infectious microorganisms and so represents a much safer environment for recreational swimming. Injuries and drowning are also much less likely in pools where trained lifeguards and safety equipment are present.

Perhaps, then, an outdoor managed swimming pool offers the best of both worlds – a swim with the sun on your back in a sanitary environment.

Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of Leicester

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Article source: https://www.theweek.co.uk/news/science-health/959834/swimming-pools-vs-wild-swimming-which-is-worse-for-germs