BACKGROUND: In Europe, avian schistosomes of the genus Trichobilharzia are the most common etiological agents involved in human cercarial dermatitis (swimmer's itch). Manifested by a skin rash, the condition is caused by an allergic reaction to cercariae of nonhuman schistosomes. Humans are an accidental host in this parasite's life cycle, while water snails are the intermediate, and waterfowl are the final hosts. The study aimed to conduct a molecular and phylogenetic analysis of Trichobilharzia species occurring in recreational waters in North-Eastern Poland. METHODOLOGY: The study area covered three water bodies (Lake Skanda, Lake Ukiel, and Lake Tyrsko) over the summer of 2021. In total, 747 pulmonate freshwater snails (Radix spp., Lymnaea stagnalis) were collected. Each snail was subjected to 1-2 h of light stimulation to induce cercarial expulsion. The phylogenetic analyses of furcocercariae were based on the partial sequence of the ITS region (ITS1, 5.8S rDNA, ITS2 and 28SrDNA). For Radix spp. phylogenetic analyses were based on the ITS-2 region. RESULTS: The prevalence of the Trichobilharzia species infection in snails was 0.5%. Two out of 478 (0.4%) L. stagnaliswere found to be infected with Trichobilharzia szidati. Moreover, two out of 269 (0.7%) snails of the genus Radix were positive for schistosome cercariae. Both snails were identified as Radix auricularia. One of them was infected with Trichobilharzia franki and the other with Trichobilharzia sp. CONCLUSIONS: Molecular identification of avian schistosome species, both at the intermediate and definitive hosts level, constitutes an important source of information on a potential threat and prognosis of local swimmer's itch occurrence, and helps to determine species diversity in a particular area.

• Klíčová slova
• Avian schistosomes, Cercariae, Cercarial dermatitis, Trichobilharzia,
• MeSH
• DNA helmintů genetika   MeSH
• fylogeneze * MeSH
• hlemýždi parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   veterinární   epidemiologie   MeSH
• jezera parazitologie   MeSH
• lidé MeSH
• Schistosomatidae * genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Polsko epidemiologie   MeSH
• Názvy látek
• DNA helmintů MeSH

Nasal bird schistosomes can cause bilharziosis in birds and have the potential to cause swimmer's itch in humans. We determined the prevalence of bird schistosomes in 106 mallards (Anas plathyrhynchos) from 11 water sources in Germany from 2014. Dissections were performed focusing on parasitic infections of the neural system. Infections with Trichobilharzia regenti (Horák et al. 1998) were found in 21% of the birds (n = 22), whereas Bilharziella polonica (Kowalewski 1895) were found between the brain membranes (meninges) and the brain, in the spinal cord or in the intestine of 12% of the mallards (n = 13). No significant influence of sex, age, and body condition between infected and non-infected animals was observed. Our study provides the first description of B. polonica from the neural system of birds and provides an epidemiological understanding of a parasite of human health concern.

• Klíčová slova
• Bilharziella polonica, Bird schistosomes, Mallard, Trichobilharzia regenti,
• MeSH
• divoká zvířata parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   veterinární   MeSH
• kachny parazitologie   MeSH
• lidé MeSH
• nemoci ptáků parazitologie   MeSH
• nervový systém parazitologie   MeSH
• Schistosoma genetika   izolace a purifikace   fyziologie   MeSH
• Schistosomatidae genetika   izolace a purifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Německo MeSH

Bird schistosomes, besides being responsible for bird schistosomiasis, are known as causative agents of cercarial dermatitis. Cercarial dermatitis develops after repeated contact with cercariae, mainly of the genus Trichobilharzia, and was described as a type I, immediate hypersensitivity response, followed by a late phase reaction. The immune response is Th2 polarized. Primary infection leads to an inflammatory reaction that is insufficient to eliminate the schistosomes and schistosomula may continue its migration through the body of avian as well as mammalian hosts. However, reinfections of experimental mice revealed an immune reaction leading to destruction of the majority of schistosomula in the skin. Infection with the nasal schistosome Trichobilharzia regenti probably represents a higher health risk than infections with visceral schistosomes. After the skin penetration by the cercariae, parasites migrate via the peripheral nerves, spinal cord to the brain, and terminate their life cycle in the nasal mucosa of waterfowl where they lay eggs. T. regenti can also get over skin barrier and migrate to CNS of experimental mice. During heavy infections, neuroinfections of both birds and mammals lead to the development of a cellular immune response and axonal damage in the vicinity of the schistosomulum. Such infections are manifest by neuromotor disorders.

• Publikační typ
• časopisecké články MeSH