Cercarial Dermatitis in Norway - An Emerging Zoonotic Disease

AbstractSection Objective

Cercarial dermatitis, often called swimmer’s itch, is a non-communicable skin condition caused by bird schistosomes. The host response is characterized by an early type I hypersensitivity reaction and a late phase of cutaneous inflammation, often leading to severe itching. Outbreaks of cercarial dermatitis in recreational waters can significantly impact public health. The aim of this present study was to describe the geographical distribution of reported cercarial dermatitis in Norway from 1980 to the end of 2023.

AbstractSection Methods

The study is based on random reports obtained from private persons, hospitals, general practitioners and environmental health sectors experiencing the problem.

AbstractSection Results

The first case of cercarial dermatitis in Norway was reported back in 1980. In the following years, an increasing number of cases were reported with a clear increase from 2010 and onwards. By the end of 2023 cercarial dermatitis was reported from a total of 414 lakes and 37 rivers. Approximately 81% are from freshwater below 300 m elevation, and 90.9% are from areas located south of the Arctic Circle at 66.3°N. As far as we know, the case report from 70.4°N is the northernmost in Europe.

AbstractSection Conclusions

The observed increased geographical distribution of cercarial dermatitis in Norway might be explained by increased water temperatures, more infected migrating birds, more suitable environmental factors facilitating snail and fluke survival, as well as increased attention in media, internet and social networks. Identification of the causative agent or agents and their geographical distribution is important for estimating the potential health risk and for designing appropriate preventive and control measures for this emerging disease in Norway.