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.

• Keywords
• Avian schistosomes, Cercarial dermatitis, Lungs, Skin, Trichobilharzia franki,
• Publication type
• Journal Article MeSH

BACKGROUND: Cercarial dermatitis (CD), or swimmer's itch, is a water-borne allergic skin reaction caused by the penetration of the larval stages of bird schistosomes (cercariae) into the skin. Members of the genus Trichobilharzia are the primary causative agents of CD worldwide. Due to the increasing number of cases, CD is regarded as a (re)emerging disease. Outbreaks in recreational waters can significantly impact public health and local economies. Environmental monitoring of Trichobilharzia is crucial for outbreak prediction and public health management. However, conventional methods, such as cercarial shedding and snail dissections, are labour-intensive and lack sensitivity. To overcome these limitations, we present a molecular toolkit that combines loop-mediated isothermal amplification (LAMP), quantitative polymerase chain reaction (qPCR), and multiplex PCR for rapid, sensitive, and accurate detection and identification of Trichobilharzia spp. from various biological samples. METHODS: Tricho-LAMP and Tricho-qPCR were designed and optimised for Trichobilharzia DNA detection. A multiplex PCR assay was also developed and optimised to identify the three main species causing CD in Europe (Trichobilharzia franki, T. szidati, and T. regenti). RESULTS: Tricho-LAMP specifically detected T. regenti and T. franki at 10-3 ng, and T. szidati at 10-2 ng per reaction with genomic DNA. Using gBlocks synthetic DNA, Tricho-LAMP achieved 100% amplification at 10,000 copies and 85% amplification at 1000 copies, with decreasing success at lower concentrations. Tricho-qPCR showed the highest sensitivity, detecting all species down to 10-4 ng per reaction and showing a limit of detection at 10 copies of synthetic DNA in the reaction. Multiplex PCR allowed reliable species differentiation via gel electrophoresis of the PCR products, but the assay had the lowest sensitivity. CONCLUSIONS: We provide a molecular toolkit consisting of LAMP, qPCR, and multiplex PCR. By exhibiting high sensitivity, Tricho-LAMP and Tricho-qPCR assays are potentially suitable for environmental DNA (eDNA)-based environmental monitoring of bird schistosomes, by both researchers and public health authorities. Multiplex PCR can be used for species determination without the need for further sequencing.

• Keywords
• Trichobilharzia, Bird schistosomes, Cercarial dermatitis, Detection, LAMP, Monitoring, Multiplex PCR, qPCR,
• MeSH
• Molecular Diagnostic Techniques * methods   MeSH
• DNA, Helminth genetics   MeSH
• Snails parasitology   MeSH
• Trematode Infections * diagnosis   parasitology   veterinary   MeSH
• Real-Time Polymerase Chain Reaction * methods   MeSH
• Multiplex Polymerase Chain Reaction * methods   MeSH
• Birds parasitology   MeSH
• Schistosomatidae * genetics   isolation & purification   classification   MeSH
• Sensitivity and Specificity MeSH
• Nucleic Acid Amplification Techniques * methods   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA, Helminth MeSH

The potential link between the infections and the development of Alzheimer's disease (AD) has led to speculations about the role of various pathogens in triggering amyloid-β (Aβ) overproduction, possibly leading to AD onset. The globally distributed dog roundworm Toxocara canis was suggested to be a suitable candidate due to neurotropism of the larvae and infection chronicity. This study investigated whether chronic T. canis infection induces AD-like pathology in mice and whether Aβ is toxic to T. canis. BALB/c and APP/PS1 transgenic mice, which overproduce Aβ, were infected with T. canis L3 larvae and monitored for larval burden, Aβ accumulation, and behavioral changes. In vitro tests of recombinant Aβ toxicity against the larvae were also performed. Despite the presence of T. canis larvae in the central nervous system 8 and 16 weeks post-infection, no significant increase in Aβ concentration or AD-related behavioral alterations were observed. Aβ was detected on the surface and within the intestines of T. canis larvae, but in vitro exposure to recombinant Aβ did not affect larval viability or morphology. Our findings suggest that T. canis infection does not trigger AD-like pathology in mice, and Aβ does not act as an antiparasitic agent. This challenges the emerging hypothesis that chronic neurotoxocarosis infections may contribute to AD development.

TITLE: Absence de preuve de pathologie de la maladie d’Alzheimer chez les souris infectées par Toxocara canis. ABSTRACT: Le lien potentiel entre les infections et le développement de la maladie d’Alzheimer (MA) a suscité des spéculations sur le rôle de divers agents pathogènes dans le déclenchement de la surproduction de β-amyloïde (βA), pouvant conduire à l’apparition de la MA. Toxocara canis, un nématode du chien, répandu mondialement, a été suggéré comme un candidat potentiel en raison du neurotropisme de ses larves et de la chronicité de son infection. Cette étude examine si une infection chronique à T. canis induit une pathologie de type MA chez la souris et si la βA est toxique pour T. canis. Des souris transgéniques BALB/c et APP/PS1, qui surproduisent la βA, ont été infectées par des larves L3 de T. canis et la charge larvaire, l’accumulation de βA et les changements comportementaux ont été étudiés. Des tests in vitro de toxicité de la βA recombinante contre les larves ont également été réalisés. Malgré la présence de larves de T. canis dans le système nerveux central 8 et 16 semaines après l’infection, aucune augmentation significative de la concentration de la βA ni d’altération comportementale liée à la MA n’ont été observées. La βA a été détectée à la surface et dans les intestins des larves de T. canis, mais l’exposition in vitro à la βA recombinante n’a pas affecté la viabilité ou la morphologie des larves. Nos résultats suggèrent que l’infection à T. canis ne déclenche pas de pathologie de type MA chez la souris, et que la βA n’agit pas comme agent antiparasitaire. Cela remet en cause l’hypothèse émergente selon laquelle les infections chroniques par neurotoxocarose pourraient contribuer au développement de la MA.

• Keywords
• Alzheimer’s disease, Amyloid-β, Infectious hypothesis, Neurotoxocarosis, Toxocara canis,
• MeSH
• Alzheimer Disease * pathology   parasitology   etiology   MeSH
• Amyloid beta-Peptides toxicity   metabolism   analysis   MeSH
• Larva MeSH
• Disease Models, Animal MeSH
• Mice, Inbred BALB C MeSH
• Mice, Transgenic MeSH
• Mice MeSH
• Dogs MeSH
• Intestines parasitology   MeSH
• Toxocara canis * physiology   growth & development   MeSH
• Toxocariasis * complications   pathology   parasitology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Dogs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Amyloid beta-Peptides MeSH

Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis (schistosomiasis) affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal schistosomes are of great veterinary importance. The order Diplostomida is also rich in species parasitizing other major taxa of vertebrates. The "Aporocotylidae" sensu lato are pathogenic in fish, "Spirorchiidae" sensu lato in reptiles. All these flukes have two-host life cycles, with asexually reproducing larvae usually in mollusks and occasionally in annelids, and adults usually live in the blood vessels of their vertebrate hosts. Pathology is frequently associated with inflammatory reactions to eggs trapped in various tissues/organs. On the other hand, the representatives of Diplostomidae and Strigeidae have three- or four-host life cycles in which vertebrates often serve not only as definitive but also as intermediate or paratenic hosts. Pathology is usually associated with migration of metacercariae and mesocercariae within the host tissues. The impact of these trematode infections on both farm and wild animals may be significant.

• Keywords
• Aporocotylidae, Blood flukes, Diplostomidae, Sanguinicolidae, Schistosoma, Schistosomatidae, Skin penetration, Spirorchiidae, Strigeidae, Trematodes,
• MeSH
• Trematode Infections * parasitology   veterinary   MeSH
• Host-Parasite Interactions MeSH
• Humans MeSH
• Schistosomatidae genetics   MeSH
• Life Cycle Stages MeSH
• Trematoda physiology   pathogenicity   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

The incidences of multiple sclerosis have risen worldwide, yet neither the trigger nor efficient treatment is known. Some research is dedicated to looking for treatment by parasites, mainly by helminths. However, little is known about the effect of helminths that infect the nervous system. Therefore, we chose the neurotropic avian schistosome Trichobilharzia regenti, which strongly promotes M2 polarization and tissue repair in the central nervous system, and we tested its effect on the course of experimental autoimmune encephalomyelitis (EAE) in mice. Surprisingly, the symptoms of EAE tended to worsen after the infection with T. regenti. The infection did not stimulate tissue repair, as indicated by the similar level of demyelination. Eosinophils heavily infiltrated the infected tissue, and the microglia number increased as well. Furthermore, splenocytes from T. regenti-infected EAE mice produced more interferon (IFN)-γ than splenocytes from EAE mice after stimulation with myelin oligodendrocyte glycoprotein. Our research indicates that the combination of increased eosinophil numbers and production of IFN-γ tends to worsen the EAE symptoms. Moreover, the data highlight the importance of considering the direct effect of the parasite on the tissue, as the migrating parasite may further tissue damage and make tissue repair even more difficult.

• Keywords
• EAE, IFN-γ, Trichobilharzia regenti, demyelination, eosinophilia, experimental autoimmune encephalomyelitis, neurotropic parasite, neurotropic schistosome,
• MeSH
• Encephalomyelitis, Autoimmune, Experimental * immunology   pathology   MeSH
• Eosinophils immunology   MeSH
• Interferon-gamma * metabolism   MeSH
• Mice, Inbred C57BL * MeSH
• Mice MeSH
• Multiple Sclerosis immunology   pathology   MeSH
• Schistosomatidae physiology   MeSH
• Spleen pathology   parasitology   immunology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Interferon-gamma * MeSH