A common problem in recreational pools is swimmer’s itch. This is an allergic skin reaction caused by the parasite Trichobilharzia. This parasite has a life cycle that starts in aquatic snail (for example: Lymnaea stagnalis and Radix ovata) and ends in a water bird (for example: Anas platyrhynchos). In the intermediate phase of the life cycle, the larva is a free-swimming organism (cercaria), looking for a new host (the bird). During this time, the parasite can cause swimmer’s itch by penetrating a human’s skin and triggering an immune response, which causes itching, red spots and bumps. These complaints will disappear after a few days without treatment and have no health consequences. However, they are experienced as very annoying and are therefore very undesirable.

The traditional test to detect Trichobilharzia consists of collecting the host’s snails from the parasite. These collected snails are then placed in a laboratory under a lamp, after which any cercaria that may be present are released from the host. Microscopically, it is then examined whether these released cercaria belong to the harmful Trichobilharzia. This microscopic analysis is essential because snails are often contaminated with other cercaria, such as e.g. Echinostoma spp. and Diplostomum spp. To treat Trichobilharzia cercaria using To be able to distinguish a microscope from cercaria, which is not a nuisance to people, requires knowledge and experience. An incorrect determination can then easily be made. Demonstrate The eDNA technique developed by Sylphium is able to detect the parasite in surface water without having to collect snails and analyze them for the presence of cercaria. With the new technique, only a small volume of surface water needs to be collected and filtered. The filtrate is then examined with the eDNA technology for the presence of Trichobilharzia DNA. The test is able to detect all Trichobilharzia species (for example: T. ocellata, T. szidati, T. stagnicolae, T. regenti, T. franki and T. querquedulae) and excludes other non-pathogenic cercaria (eg Echinostoma spp. and diplostomum spp.). The eDNA technology offers great sensitivity, specificity and reproducibility for Trichobilharzia. Due to the simple and fast sampling method, sampling can take place several times in time and in this way the end of the contamination can be determined earlier, after which the bathing water can be quickly opened up to the public again. This analysis method is intended to demonstrate direct contamination of the surface water with Trichobilharzia. This means that, based on complaints received, it is checked whether these complaints are caused by Trichobilharzia or whether the complaints are caused by something else. Do you have a question about our analysis or do you want to request a free test, please fill in and send the form below.


In addition to demonstrating a Trichobilharzia infection, it can also be important to know the exact identity of the Trichobilharzia species. If the swimmer’s itch analysis is positive, it can be decided to determine the species by having a DNA sequence analysis performed by Sylphium. The obtained sequence is then compared to a DNA database to identify the species. The additional costs for this analysis are € 165 (ex. VAT).

Oak processionary caterpillar

Swim itch-like skin conditions can also be caused by other factors. A common problem is the stinging hairs of the oak processionary caterpillar. Like cercaria, these cause a strong immune response with itching, red spots and bumps. These hairs spread through the air and also end up in the surface water. Sylphium can also identify these hairs using eDNA. This analysis indicates whether oak processionary caterpillars occur near the swimming pool and can be responsible for the complaints. This analysis can be performed simultaneously in addition to the Trichobilharzia analysis and the additional costs for this analysis are € 25 (ex VAT).


We offer this test for bodies involved in the monitoring of bathing water quality. The person concerned can take the water samples themselves in a very simple and quick manner and filter them according to a filter protocol drawn up by us. The filter with the resulting filter residue is then sent by post to our laboratory where the analysis for the presence of Trichobilharzia DNA is then carried out. Reporting of the eDNA analysis on Trichobilharzia DNA will take place (digitally) within 24 hours (on working days) after receipt of the filter residue.