Cercarial dermatitis B65.3

Cortist WW, 1928

Worldwide occurring worm disease, caused by the incorrect colonization of humans with larvae of the species of sucking worms:

• Orniothobilharzia
• Austrobilharzia
• Bilharziella
• Trichobilharzia
• Gigantobilharzia

In Europe, bilharzilla, trichobilharzia, gigantobilharzia are responsible for the disease.

The physiological final host of the flukes from the above mentioned genera are birds, in most cases ducks. After the larvae of the worms have penetrated through the skin of the birds, they develop in blood vessels near the intestines into sexually mature sucker worms. These lay their eggs there. These enter the birds' intestines and are excreted with the faeces.

The larvae of the 1st generation (miracidia) develop in the water. These infest another intermediate host, mostly snails of the genera Limnae and Radix (pulmonary snails). Afterwards, larvae of the 3rd generation (cercaria) develop via another larval stage and a 3rd intermediate host (fish). As water temperatures rise in spring and summer, Cercarians search for their natural final host (birds) again, thus closing the cycle.

Bathing humans can be attacked accidentally (false host), whereby the cercaria, which are drilled into the skin, cannot develop further. They die off.

Central European waters with occurrence of freshwater snails of the genus Limnaea and Radix.

Bathing in waters contaminated with cercaria, penetration of the cercaria into the human skin, where they soon die. Man is a false host; mainly water birds are attacked, intermediate hosts are water snails.

trunk and extremities, in places not covered by the swimwear

Strongly itchy, 0.2-0.5 cm large, red or even haemorrhagic papules and wheals at the invasion sites, a few minutes up to one hour after exposure Duration until complete healing: about 10-20 days. Persons already sensitized by previous contact may develop a generalized maculopapular exanthema 10-24h after repeated exposure.

The anamnesis with reference to bathing in open waters as well as the infestation pattern (parts of the body not covered by the swimsuit) lead to a suspected diagnosis.

Trombidiosis: Urticarial exanthema under tight-fitting clothing. No relation to swimming event.

Cnidarian larval dermatitis caused by larvae of the jellyfish Linuche unguiculata after swimming. This occurs mainly in the western tropical Atlantic(salt water). An urticarial exanthema is triggered by the cnidocytes of the larvae. However, these typically occur under swimwear.

Urticaria: variable wheal formations. No relation to a single bathing situation.

No specific therapy available. By strong terracing (massaging), an attempt can be made to mechanically remove the cercaria from the upper layers of the epidermis.

Blande dehydrating therapy with e.g. Lotio alba, in case of itching addition of 2-5% Polidocanol R200. Alternatively, short-term application of topical glucocorticoids such as hydrocortisone (Hydro-Wolff, Hydrogalen R121, R123 ).

Passenger setting on oral antihistamines: Levocetirizine (e.g. Xusal) 1 tbl/day or Desloratadine (e.g. Aerius) 1 tbl/day. Possible sedative antihistamines: clemastine (e.g. Tavegil) 2 times/day 1 tbl. p.o. or dimetinden (e.g. Fenistil) 2 times/day 1 tbl. p.o.

1. Kolářová L et al (2013) Cercarial dermatitis, a neglected allergic disease. Clin Rev Allergy Immunol 45:63-74.
2. Omar HM ET AL. (2016) Gigantobilharzia, possible cause of cercarial dermatitis: Case report. Int J Health Sci (Qassim) 10:147-Q50.
3. Selbach C et al (2016) Estimating the risk of swimmer's itch in surface waters - A case study from Lake
4. Baldeney, river dysentery. Int J Hyg Environ Health 219:693-699.
5. Stanger Ch (2015) Cercaria dermatitis. In: E.v.Stebut (Ed.) Traveler dermatoses. P.176-177. Springer-Verlag Berlin, Heidelberg
6. Veleizán AA et al (2016) Cercarial dermatitis of bathers in northern Argentine Patagonia. Medicina (B Aires) 76:25-29.