Fresh water, salt water and contaminated water
Swimming in fresh water. Some parasites such as Schistosoma and Naegleria live in fresh water in certain parts of the planet. Swimming in rivers or lakes in tropical zones is not recommended. Thermal areas or untreated pools should also be avoided, due to the potential risk of contagion by these germs.
Swimming in salt water. In the sea, you must be careful of jellyfish stings and use footwear that protects from bites and stings from fish, dermatitis from coral, and against toxic crustaceans, shellfish and sea anemones.
Jellyfish sting upon contact with their tentacles. For this reason, you should avoid making sudden movements in the water. Never touch them, even if they are not in the water and appear dead. The stinging cells in their filaments may remain active and can still cause harm.
In addition to filtering radiation, using sun cream acts as an isolating layer against jellyfish tentacles and other toxic species or substances that float in the water.
The most common symptoms of a jellyfish sting are immediate pain and itching, burning, swelling, reddening and even bleeding. In these cases, you must get out of the water and see the lifeguards. If the victim’s condition worsens after half an hour, they should immediately go to a healthcare centre.
Recommendations for jellyfish stings
Wash the wound with salt water (never fresh water, as it can rupture the stinging cells). Do not itch or rub the skin with sand or a towel, but do remove the remains of the tentacles if they are evident.
If you know which species caused the sting, you can receive more specific treatment. For Pelagia noctiluca, which is the most common in Spanish waters, an aqueous solution with a 1:1 concentration of baking soda is recommended. Substances such as ammonia are not recommended as they irritate the skin and are also ineffective for certain species.
Apply cold using a plastic bag filled with ice for around 15 minutes to relieve the pain and make the venom partially degrade. This will also reduce the intensity of the wound, if too much time has not passed. Because it is a wound, it must be cared for to ensure it does not become infected. Using an antiseptic such as tincture of iodine and covering with bandages help the wound to heal.
Contaminated water. Some diseases, such as leptospirosis, are transmitted by contact with water contaminated by animal urine or excrement. It is not only fresh water that presents a risk. There are also bacteria that can survive in salt water, such as bacteria of the genus vibrio, which includes cholera and others of the same family.