Bath dermatitis

Tanja Unterberger studied journalism and communication science in Vienna. In 2015 she started her work as a medical editor at in Austria. In addition to writing specialist texts, magazine articles and news, the journalist also has experience in podcasting and video production.

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Bathing dermatitis (also known as cervical dermatitis) is an itchy rash caused by certain suction worm larvae (cercaria). When bathing in fresh water, the parasites penetrate the surface of the skin. At the entry points, those affected develop reddened spots, wheals and severe itching. Find out here how to recognize cercaria in water and how to treat bath dermatitis!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. B65

Brief overview

• Description: Itchy rash after swimming in fresh water, caused by the penetration of certain sucking worm larvae (cercaria) into the skin.
• Treatment: Anti-itch and anti-inflammatory ointments, gels or lotions (rarely also ointments containing cortisone) and cold compresses. If the itching is severe, the doctor will prescribe antihistamines (antiallergic drugs).
• Causes: Parasites (cercaria) that penetrate the skin when swimming in freshwater and lead to an inflammatory skin reaction.
• Symptoms: After bathing, tingling and itching appear on the skin, later reddened and raised spots (wheals) and small skin nodules (papules).
• Diagnosis: Talk to the doctor, examine the skin, if necessary blood test. The doctor usually recognizes bathing dermatitis by the typical symptoms and the appearance of the skin after swimming.
• Course: The skin changes often disappear on their own within a week to 20 days. Severe allergic reactions with dizziness, fever and shock are rare.
• Prevention: Avoid shallow waters, shower and dry off well after swimming, change wet swimwear, apply waterproof sunscreen.

What is bath dermatitis?

If itchy pustules form on the skin after swimming in the bathing lake, it may be due to bathing dermatitis (also called cervical dermatitis).This is a rash caused by the larvae of various types of flukes (trematodes, schistosomes). The cercaria refer to the larval forms of the flukes.

These penetrate up to a few millimeters into the skin, where they trigger the typical symptoms. Usually the parasites only attack waterfowl and certain water snails in order to reproduce. They mistakenly attach to humans because they cannot reproduce here and die after a short time. Man is a so-called false host.

Especially children, who mostly spend time in shallow water, and allergy sufferers are affected by bath dermatitis. The infestation of water bodies with cercaria is increasing worldwide.

In popular parlance, bathing dermatitis is also known as duck fleas, duckworm disease, dog-leafing or pond bite.

What are cercaria?

The larvae of flukes are called cercaries. These are parasites that are barely or not visible in the water with the naked eye. Cercaria usually infest waterfowl.

The parasites stay on the surface of the water on hot, sunny days and try to get into the bloodstream through the skin and blood vessels in the webs of water birds. The cercariae have small suction cups (hence the term flukes) on their stomach and head, which make it easier for them to “dock” with the host.

Occasionally, the larvae dig into the skin of humans. Then they trigger an itchy rash on the skin - bathing dermatitis develops.

Where do cercaria occur?

In this country, cercariae, which cause bathing dermatitis, occur in freshwater lakes (bathing lakes). Above all, they prefer standing, shallow and warm water. They survive there for about two to three days. Usually the larvae stay on the surface of the water.

The larvae usually hatch in early summer and multiply especially at temperatures above 24 degrees Celsius. Long-lasting summer weather with water temperatures above 20 degrees Celsius generally promote the development and reproduction of the larvae.

Even if there are many water birds and water snails in the areas, this favors the spread of the cercaria, as these animals serve as hosts for the parasites. In addition, the larvae like to stay in reed belts and areas with many aquatic plants.

The unpleasant but largely harmless bath dermatitis has nothing to do with a parasitic disease that is also triggered by cercaria - schistosomiasis. This is a serious disease caused by the sucking worm larvae of the pair of leeches. This is native to the tropics and subtropics.

There are no cercariae in chlorinated water, such as in outdoor swimming pools or pools.

How do you treat bath dermatitis?

Anti-inflammatory creams and gels

The doctor first treats the acute symptoms. Antipruritic and anti-inflammatory ointments, gels or lotions are particularly suitable.

Home remedies

Home remedies such as cold compresses, essential oils (e.g. menthol or cineole) and aloe vera or witch hazel gel can also help with bath dermatitis. They cool, soothe and relieve itching.

Cooling pads placed on the affected area of ​​skin also help against itching. Important: Wrap the pad in a towel to prevent damage to the skin from the cold.

Only use home remedies after consulting your doctor!

Antihistamines

If the symptoms are more pronounced, the doctor may prescribe antihistamines (antiallergic agents) in the form of gels or roll-ons (e.g. with the active ingredients mepyramine or diphenhydramine), which the person concerned applies to the skin. In severe cases, he prescribes antiallergic drugs as tablets, drops or solutions (e.g. with the active ingredients cetirizine, loratadine or fexofenadine), which the person concerned takes.

It is not necessary to fight the larvae with antibiotics or special drugs against parasites, as they die a short time after penetration.

cortisone

The doctor can also prescribe creams containing cortisone. These have anti-inflammatory and anti-allergic effects and relieve itching. Cortisone tablets are only used if the bath dermatitis is particularly severe in rare cases.

Do not scratch

It is important not to scratch in the case of bathing dermatitis: Otherwise the skin will be injured, which may become infected with bacteria.

If those affected develop severe allergic reactions after bathing, such as dizziness, sweating, fever and / or nausea, these must be treated immediately. Call an emergency doctor immediately!

What causes bathing dermatitis?

The skin symptoms of cervical dermatitis are caused by the larvae of various types of flukes (trematodes, schistosomes), which inadvertently choose humans as their host. Usually waterfowl serve as main hosts for worms, snails as intermediate hosts.

The larvae grow into worms in water birds (e.g. mallards) and produce eggs there. The worm eggs get into the water via the droppings of the worm-infested water birds. Small larvae hatch from them and normally attack a specific freshwater snail.

The larvae multiply in the snail and are released back into the shallow water after a few weeks. The new generation of larvae (cercaria) is now looking for water birds (especially ducks), which they attack and in whose intestines they develop into adult worms.

When looking for a host, the larvae sometimes mistakenly infest humans and penetrate the skin of those affected. There they are fought by the immune system and die after a short time (within hours). On first contact with the larvae, those affected usually only develop a slight skin reaction. Swimmers therefore usually do not feel the first skin contact with cercaria.

Only the second time - when the immune system recognizes the intruder - does the body react with a stronger defense reaction, which leads to the typical rash and severe itching.

The occurrence of cercaria is not related to the hygienic water quality of bathing lakes.

What does bath dermatitis look like?

After the larvae have penetrated the skin, those affected start tingling, tingling, slight itching or burning - similar to a mosquito bite. Red spots appear on the affected areas. These symptoms also occur when cercariae first invade the body.

Sensitized people who are attacked by the parasites again, the actual skin rash (dermatitis) appears after about ten to 25 hours, which sometimes occurs all over the body: This is accompanied by severe itching, much more intense than, for example, a mosquito bite . In addition, reddened, swollen wheals (point- to plateau-shaped elevations on the skin) and papules (round to oval nodules) form on the affected areas of the skin.

As soon as the itching subsides, the wheals and papules turn into small, rough bumps and then heal without consequences after a week to 20 days. However, if those affected scratch the itchy wheals, it is possible that bacteria infect the resulting wounds and the skin becomes inflamed.

In the case of particularly sensitive (allergic) people or with a strong infestation with cercaria, it is also possible in rare cases that additional symptoms such as lymph node swelling, fever, nausea and / or circulatory disorders up to states of shock occur.

Bath dermatitis is not contagious. Swallowing bath water does not cause cervical dermatitis either. Cercaria enter the body only through the skin.

How does the doctor make a diagnosis?

If you suspect that you are affected by bath dermatitis, it is best to contact your family doctor or dermatologist (dermatologist). The doctor makes a suspected diagnosis based on typical symptoms such as itching and the appearance of the skin (e.g. wheals, reddened skin, papules).

When talking to the doctor (anamnesis), it is particularly important to know that you have been in the open water beforehand. Not least in order to largely rule out other skin diseases such as insect bites or other allergies.

The doctor can reliably diagnose bathing dermatitis through a microbiological examination of the bathing water - and a blood test in which he tests the person's blood for antibodies against larval components.

To check the water for infected snails, it is possible to put the snails in glasses with water. After a while, the larvae leave the snail, which can be seen under the microscope. However, such examinations are usually not necessary.

If bathing dermatitis occurs regionally and over time in swimmers and bathers, this gives the doctor further information.

How dangerous is bath dermatitis?

The rash of bath dermatitis is uncomfortable for those affected because of the intense itching, but is usually harmless. The skin changes often heal by themselves and without consequences within a week, at the latest after 20 days.

If those affected scratch the wheals, infections can develop. Then the healing usually takes longer.

Bathing dermatitis can, however, develop very differently from person to person. It is also different from person to person. Sensitive (hypersensitized) allergy sufferers may under certain circumstances develop fever and shock, which must be treated immediately by a doctor.

How can you prevent it?

To protect yourself from cervical dermatitis, certain behavioral measures are helpful when swimming in open water. Please note the following:

• Cercaria are mainly found in warm shallow water. You should therefore avoid shallow bank zones. Those who swim a little further out are safe in the deeper and cooler waters.
• Don't be too long in shallow water. Several shorter bathing intervals reduce the risk of cercariae infecting the skin.
• After bathing, shower yourself carefully with clean water to rinse any cercariae off the skin.
• After bathing, it is important that you dry off yourself well. By toweling the skin, you remove the larvae.
• It is best to change wet swimwear immediately.
• Rubbing the skin with waterproof sun creams also offers a certain amount of protection. This makes it more difficult for the parasites to penetrate the skin.
• As a preventive measure, it is also advisable not to feed ducks at bathing areas so as not to attract the animals additionally. The more ducks there are, the higher the risk of cercaria infestation.

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