Authors

J Bulantová¹; Z Pokrupová¹; P Pumann²;  ¹ Charles University, Faculty of Science, Czech Republic;  ² National Institute of Public Health, Czech Republic

Discussion

Research of avian schistosomes and cercarial dermatitis, which they cause, is primarily focused on morphology, taxonomy, and basic biology. More advanced research focuses on ecology or immune, biochemical or protein interactions of parasites and their natural/accidental host, including humans. However, most of the gained findings are often unable to satisfactorily answer the basic questions asked by public health authorities, who are newly responsible for routine monitoring of causative agents of cercarial dermatitis in official recreational areas. Remarkably, monitoring of cercariae of avian schistosomes in official bathing sites by competent authorities is not standard in the countries concerned. In the Czech Republic, monitoring of schistosomes belongs to the regulations to assess bathing water quality only since 2020.
In the last several years, researchers worldwide were more often asked for help identifying avian schistosomes in recreational water bodies where people are affected by cercarial dermatitis. Besides the primary methods used, including examining collected intermediate snail hosts for cercariae, they reflected the call for a more straightforward, faster, and cheaper process. The method should be suitable for routine preventive monitoring of avian schistosomes before cercarial dermatitis appears to warn bathers adequately.
One possible way to meet the requirements mentioned above is to detect the parasite within the pond water, filter it and subsequently process it to analyze environmental DNA (e-DNA). This method was already successfully tested for some genera of avian schistosomes in several countries and showed promising results. Nevertheless, the novelty of the technique, lacking verification and adjustment for species diversity found in the Czech Republic, necessary equipment, and experienced staff in routine non-research laboratories, does not allow us to use it in practice.
Although optimization of e-DNA monitoring of avian schistosomes in the Czech Republic is at the beginning, intensive cooperation between competent authorities (public health authorities and public health labs), universities, and researchers resulted in a series of thematic lectures and short workshops on cercarial dermatitis. As a result, a continuously updated map summarizing the recent occurrence of avian schistosomes and cercarial dermatitis in the Czech Republic is known, including the data from the first description of this disease.
Basic research sometimes seems not to be usable in practice at first glance. Nevertheless, in this case, all segments helped each other to keep actual our knowledge about the occurrence, frequency, and recurrence of cercarial dermatitis in our country. A comparison of the traditional snail sampling method and the e-DNA approach is planned as the next step of this cooperation.