Acta Dermato-Venereologica 99-12CompleteContent | Page 16

1116 CLINICAL REPORT Outbreak of Swimmer’s Itch in Denmark Eva Susanna TRACZ 1# , Azmi AL-JUBURY 2# , Kurt BUCHMANN 2 and Anette BYGUM 3 Department of Dermatology, Aarhus University Hospital, Aarhus, 2 Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, and 3 Department of Dermatology and Allergy Centre, Odense University Hospital, Odense, Denmark # These authors contributed equally and should be considered as first authors. 1 Swimmer’s itch, or cercarial dermatitis, is a waterbor- ne non-communicable skin condition caused by schis- tosome cercariae released by aquatic snails. Cercarial dermatitis appears worldwide, but may be caused by different trematode species. The itchy maculopapu- lar rash develops on exposed areas of the skin and typically resolves within 1–3 weeks. Shedding of in- fective larvae from snails is temperature dependent, and high temperatures and sunshine increase the risk of encountering the parasite and becoming infected. The unusually warm spring and summer of 2018 led to an increasing number of reports of the condition in Denmark and established a collaboration between the Department of Dermatology and the Faculty of Health and Medical Sciences, Department of Veterinary and Animal Sciences. This study explored the clinical pic- ture of the disease, and demonstrated the occurrence of infected fresh water snail species in selected Danish water bodies. In conclusion, a risk of swimmer’s itch in Denmark was confirmed. Key words: swimmer’s itch; cercarial dermatitis; Trichobilhar- zia. Accepted Aug 26, 2019; E-published Aug 27, 2019 Acta Derm Venereol 2019; 99: 1116–1120. Corr: Eva Susanna Tracz, Department of Dermatology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus N, Denmark. E-mail: [email protected] S wimmer’s itch, or cercarial dermatitis, is a waterborne non-communicable skin condition. It is caused by various species of skin-penetrating schistosome cercariae (1), which are larval flatworm parasites emerging from aquatic snails that occur worldwide, usually in freshwa- ter. The avian schistosomes most often responsible for the infection have a 2-host lifecycle: snails as interme- diate hosts and birds as final hosts. These non-human schistosomes are considered unable to complete their development in human hosts, where they become entrap- ped in the skin and die soon after penetration, inducing an intense inflammatory response (2). A few hours after exposure to water carrying infective cercariae, the affected person develops an itchy maculo- papular rash, limited to areas immersed in water. The itch becomes more intense and the rash typically develops with papules and vesicles during hours or a few days after exposure. The disease is self-limiting within 1–3 weeks. doi: 10.2340/00015555-3309 Acta Derm Venereol 2019; 99: 1116–1120 SIGNIFICANCE Swimmer’s itch is an emerging disease in Europe, which is usually considered benign. This study explores the clini- cal picture of the disease, demonstrates the occurrence of the causative parasite in selected Danish water bodies, and confirms the risk of swimmer’s itch in Denmark. If repeated exposures occur, the reaction is often more rapid and severe, indicating sensitization and allergic reactions (2–4). In temperate climates, swimmer’s itch is a seasonal disease mainly diagnosed during summer months, when both the number of open-water activities and snail release of cercariae reach peak levels (5). The period from spring to the end of summer 2018 was unusually warm (6). Open-water activities flourished and so did the parasites. Increased reports of eruptions re- sembling swimmer’s itch began to emerge locally and in the media, reaching the Danish Nature Agency and local dermatologists. This led to a collaboration between the Department of Dermatology, Odense University Hospital and the Faculty of Health and Medical Sciences, De- partment of Veterinary and Animal Sciences, University of Copenhagen, with the aim of further exploring the clinical picture of swimmer’s itch and investigating the occurrence of Trichobilharzia infected snails in selected Danish water bodies. MATERIALS AND METHODS A protocol was prepared and submitted to the Data Protection Agency, which approved the data collection [Jr 18/41986]. Invi- tations were published using the homepage of the Danish Nature Agency, the mailing list of the Danish Society of Dermatologists, and local bulletins for persons experiencing a rash after bathing in freshwater lakes. Affected persons were invited to contact our department by phone or e-mail. Those who contacted the depart- ment were asked to send pictures of the rash for dermatological evaluation; they were offered a clinical examination in case of actual eruption, and asked to complete a questionnaire. Information was gathered about age and sex, bathing coordinates, duration of bathing, latency before skin eruption, a description of the rash, location, duration, treatment and accompanying symptoms, such as fever, malaise, physician contact or hospitalization. Data on comorbidities and other therapies were also collected. In parallel, in order to assess the risk of swimmer’s itch and the occurrence of avian schistosomes, we visited the la- This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.