Cercarial dermatitis (CD; swimmer's itch) is a re-emerging skin disease caused by avian schistosomes, including Trichobilharzia franki. Here, we present morphological, genetic, and experimental evidence confirming the involvement of T. franki in recent CD outbreaks across Czechia. Ocellate furcocercariae were collected from Radix auricularia at four sites and identified as T. franki through ITS1 sequencing. Despite minor morphological differences from previously reported specimens, all isolates belonged to the genetically uniform T. franki "auricularia" clade. Experimental infection of mice with T. franki resulted in a ∼ 60 % penetration rate, accompanied by early-onset scratching and transient weight loss. Gross pathology demonstrated hemorrhages on lung surfaces and splenic atrophy at 2 days post-infection (dpi), along with a prominent enlargement of parotid lymph nodes at both 2 and 7 dpi. Histological examination of the skin revealed viable schistosomula, moderate leukocyte infiltration, epidermal hyperplasia, and the formation of hyperkeratotic crusts at 2 dpi. By 7 dpi, parasites were no longer detectable, but epidermal pathology persisted. In the lungs, eosinophil-rich foci and multifocal hemorrhages were observed at 2 dpi, transitioning to neutrophil-dominated lesions at 7 dpi, despite the absence of detectable schistosomula. Splenocytes from infected mice responded to homologous and heterologous cercarial antigens by producing IFN gamma, IL-4, and IL-10, indicating a mixed Th1/Th2/Treg profile and notable species cross-reactivity. However, parasite-specific IgG remained undetectable at 7 dpi. These findings confirm T. franki as the causative agent of CD outbreaks and underscore its capacity to induce localized and systemic pathology and immune response, cross-reacting with other schistosomes.

• Klíčová slova
• Avian schistosomes, Cercarial dermatitis, Lungs, Skin, Trichobilharzia franki,
• Publikační typ
• časopisecké články MeSH

Cercarial dermatitis (swimmer's itch) is a condition caused by infective larvae (cercariae) of a species-rich group of mammalian and avian schistosomes. Over the last decade, it has been reported in areas that previously had few or no cases of dermatitis and is thus considered an emerging disease. It is obvious that avian schistosomes are responsible for the majority of reported dermatitis outbreaks around the world, and thus they are the primary focus of this review. Although they infect humans, they do not mature and usually die in the skin. Experimental infections of avian schistosomes in mice show that in previously exposed hosts, there is a strong skin immune reaction that kills the schistosome. However, penetration of larvae into naive mice can result in temporary migration from the skin. This is of particular interest because the worms are able to migrate to different organs, for example, the lungs in the case of visceral schistosomes and the central nervous system in the case of nasal schistosomes. The risk of such migration and accompanying disorders needs to be clarified for humans and animals of interest (e.g., dogs). Herein we compiled the most comprehensive review of the diversity, immunology, and epidemiology of avian schistosomes causing cercarial dermatitis.

• MeSH
• biodiverzita MeSH
• epidemický výskyt choroby MeSH
• hostitelská specificita MeSH
• lidé MeSH
• nemoci ptáků parazitologie   přenos   MeSH
• parazitární onemocnění kůže epidemiologie   imunologie   parazitologie   prevence a kontrola   MeSH
• ptáci MeSH
• schistosomóza epidemiologie   imunologie   parazitologie   prevence a kontrola   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH