Cercaria - Cercarial Dermatitis, Bath Dermatitis

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Cercaria - Cercarial Dermatitis, Bath Dermatitis
Cercaria - Cercarial Dermatitis, Bath Dermatitis

Video: Cercaria - Cercarial Dermatitis, Bath Dermatitis

Video: Cercaria - Cercarial Dermatitis, Bath Dermatitis
Video: The Horrifying Truth About Swimmer's Itch 2023, September

Bath dermatitis (cercaria)

After swimming in stagnant water, you may occasionally experience unpleasant skin conditions. Especially in midsummer, when there are already long periods of heat and the bathing water is between 26 and 28 degrees Celsius for longer, cases of bathing dermatitis can accumulate to epidemic - especially if animals such as water snails and ducks live in the water.


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  • Advice, downloads & tools
  • What are the causes of bath dermatitis?
  • Difference between bathing dermatitis and schistosomiasis
  • How is bath dermatitis transmitted?
  • What are the symptoms?
  • How to prevent bathing dermatitis
  • ">How is the diagnosis made?
  • ">
  • How is bath dermatitis treated?
  • How are the costs going to be covered?
  • Bathing water quality in Austria

This skin disease is usually triggered by certain larval stages (cercaria) of flukes (certain types of schistosomes), which also penetrate the human skin and can lead to discomfort if they come into contact several times. The severe itching and possible inflammation of the skin are very unpleasant, but bathing dermatitis is a harmless skin disease. Even without therapy, it subsides by itself after a few days without any consequences. However, certain preventive behaviors can counteract bathing dermatitis.

Bathing dermatitis is also known under the following terms:

  • Cervical dermatitis,
  • Swimming dermatitis,
  • Schistosomal dermatitis,
  • Dog paws,
  • Duckworm disease as well
  • "Swimmer's itch".

What are the causes of bath dermatitis?

Cercariae are tiny larvae of various types of flukes (trematodes, schistosomes) that go through a certain cycle in nature. They are barely or not perceptible to the naked eye. The adult worms live in water birds (eg mallards) and produce eggs that are released into the water with the excrement. In the water, an eyelash larva (Miracidium) leaves the egg and penetrates a water snail (intermediate host), where it multiplies and transforms. The end product of this metamorphosis in the snail are the cercariae, which leave the snail and then try to invade waterfowl (final host). These have small suction cups on their stomach and head that make it easier for them to “dock” with a host.

In their search for the ultimate host, however, the larvae can “get lost” and dock on the human skin. However, they cannot develop further in the “false host” and die within hours. Nevertheless, the complaints are unpleasant.

Note In the human organism, cercaria cannot develop into "adult" leeches. They still die in the skin.

Difference between bathing dermatitis and schistosomiasis

The common bath dermatitis must be differentiated from another parasitic disease that is also caused by cercariae of other types of flukes: This is schistosomosis / schistosomiasis / schistosomiasis - a serious disease with possible involvement of the intestines, liver and lungs, urinary tract or central nervous system. Those schistosome species that cause schistosomiasis can develop further in the human organism (Schistosoma mansonii, S. haematobium, S. japonicum). These species do not occur in Austria. Cases of illness are, for example, travelers returning from endemic areas or patients from endemic areas such as Africa, Brazil, Venezuela, Yemen, Iraq, Syria, China, Laos, Cambodia, Philippines or Sulawesi. A country map of schistosomal endemic areas can be found on the WHO website at www.who.int.

According to the Austrian Agency for Health Food Safety (AGES), the pathogens causing bath dermatitis in Austria are mainly Trichobilharzia szidati and Bilharziella polonica, which after penetrating the skin cannot develop in the human body and die quickly.

How is bath dermatitis transmitted?

Cercariae, which can cause bathing dermatitis, can be found in stagnant freshwater, primarily with shallow water. They occur less often in deeper water zones. As parasites, they can only multiply and thrive if their required hosts - water snails and ducks - are present.

Factors that favor the appearance of cercaria:

  • standing fresh water,
  • low water depth (bank edge),
  • Presence of aquatic snails and birds,
  • Reed belts or other aquatic plants,
  • longer periods of heat,
  • high bathing water temperature (longer time between 26 to 28 degrees Celsius),
  • artificial, species-poor open water that is difficult to compensate for extreme environmental conditions such as heat waves.

What are the symptoms?

If it comes to the first contact with the larva, there are usually no severe skin reactions. A slight reddening with a burning sensation and tingling or tingling of the skin is possible after just a few minutes. The typical symptoms only occur after repeated contact (sensitization) with the larvae. The body recognizes the intruder and reacts through allergic-toxic processes with an immediate or delayed skin reaction, resulting in an itchy rash. Symptoms usually appear one day after contact with the cercariae and can last a week to a little longer. Typically, the rash develops on the feet or lower legs. Fever and circulatory disorders can occur in particularly sensitive people.

Typical symptoms of bath dermatitis:

  • Reddening of the skin,
  • Itching,
  • palpable pustules or wheals.

Note Cercarial dermatitis is not contagious. Swallowing bath water does not cause cercarial dermatitis. The infection occurs exclusively through the skin.

How to prevent bathing dermatitis

Certain open water swimming behaviors can prevent, if not completely, bath dermatitis.

  • Do not swim, dive or wade in shallow water for too long, but rather swim deep.
  • Drying off well with a hand or bath towel immediately after being in the water can prevent bathing dermatitis, but does not provide reliable protection.
  • Wet swimwear should be changed after swimming and rinsed with tap water.
  • Avoid feeding ducks or geese in bathing waters as it can attract the aquatic animals and could lead to preferential settlement in the bathing water.
  • Fatty creams etc. represent a certain barrier for the larvae and make it more difficult to penetrate the skin. Certain sun and bath creams that contain niclosamide as well as jellyfish repellants have a protective effect.

Note Swimming in chlorinated water, such as in outdoor pools or pools, does not pose a risk, as it cannot contain cercaria.

How is the diagnosis made?

The doctor uses the clinical symptoms such as itching and rash to make judgments, making sure that it is not another (skin) disease (differential diagnosis). It is particularly important to be informed by the patient that they have swum in open water. In connection with the typical symptoms, a suspected diagnosis is usually made. It is not necessary to underpin the diagnosis with a blood test, biopsy or taking water at the seaside resort. Regionally and chronologically more frequent occurrences of bathing dermatitis usually give the doctor clear indications.

How is bath dermatitis treated?

If you suspect you have bathing dermatitis, it is best to contact the following offices.

  • General practitioner
  • Dermatologist (Dermatologist)

Bathing dermatitis usually heals by itself after a day to a maximum of three weeks. If the itching is severe and the skin overreacts or if there is a fever or poor circulation, it is advisable to consult a doctor. If the itching is severe or if inflammation occurs as a result of scratching, anti-itch or anti-inflammatory ointments or gels can be used. In the short term, mild glucocorticoids can be used for external application. Sometimes an antihistamine is prescribed for ingestion to reduce the skin reaction, and in the case of a fever, an antipyretic may be prescribed.

How are the costs going to be covered?

The e-card is your personal key to the benefits of the statutory health insurance. All necessary and appropriate diagnostic and therapeutic measures are taken over by your responsible social insurance agency. A deductible or contribution to costs may apply for certain services. You can obtain detailed information from your social security agency. Further information can also be found at:

  • Right to treatment
  • Visit to the doctor: costs and deductibles
  • What does the hospital stay cost?
  • Prescription fee: This is how drug costs are covered
  • Medical aids & aids
  • Health Professions AZ

and via the online guide to reimbursement of social insurance costs.

Bathing water quality in Austria

The occurrence of cercaria in bodies of water does not allow any conclusions to be drawn about water quality or hygiene. In contrast, the level of E. coli and enterococci serves as an indicator of the presence of pathogens.

According to an EU directive on the quality of bathing water, there are uniform rules for the examination and assessment of bathing water. Accordingly, the Austrian Agency for Health and Food Safety (AGES) provides clear measurement data on water quality, visibility depth and temperature in the bathing water database. This is also available free of charge as an app for on the go. For more information, see Bathing Water Database.

You can find the apps under Bathing waters in the Playstore or Bathing waters in the Appstore.