Description of Myxobolus balatonicus n. sp. (Myxozoa: Myxobolidae) from the common carp Cyprinus carpio L. in Lake Balaton

Myxobolus balatonicus n. sp. was detected in the gill filaments of the common carp Cyprinus carpio L. collected in Lake Balaton, Hungary. Its oval plasmodia measuring 600–800 × 300–400 µm were located intravasally in the filamental arteries. The spores measured 11.2 ± 0.92 × 9.5 ± 0.41 × 7.4 ± 0.33 µm and had two equal polar capsules with six filamental turns. Both morphology and DNA sequence analysis revealed that M. balatonicus n. sp. is distinct from the ten species of Myxobolus Bütschli, 1882 described from the European common carp and the 21 species described from the Asian common carp subspecies. Phylogenetic analysis placed M. balatonicus n. sp. in a clade of gill-infecting myxobolids

Balatoni halfajok és köztigazda szervezetek parazitológiai monitorozása = Parasitological monitoring of fish species and intermediate hosts organisms in Lake Balaton

A kutatás négy éve alatt, 2008-2012 között, a Balaton és vízrendszere több mintavételi helyén rendszeres gyűjtéssel követtük nyomon a halak és köztigazda szervezetek parazitás-fertőzöttségét. Új nyálkaspórás fajokat írtunk le balatoni halakból, több nyálkaspórás faj teljes fejlődésmenetét-, vagy intraoligochaeta-fejlődésmenetét tisztáztuk, kísérletes és molekuláris biológiai módszerekkel. A halakban élősködő főbb féregcsoportok közül elsősorban a mételyek, és a puhatestűekben élősködő métely-lárvák vonatkozásában értünk el új eredményeket. Rámutattunk egy rákparazita szerepére a 2009-ben történt szelektív balatoni dévérkeszeg-elhullásban. Három invazív kagyló faj balatoni megjelenéséről tudósítottunk. Virológus kollégáinkkal kooperálva elsőként mutattunk ki cirkovírusokat halakból. Új eredményeinket konferencia anyagokban, tudományos lapokban, ill. könyvfejezetben jelentettük meg. Az OTKA téma segítségével több külföldi kooperációban készült munka is megvalósult (Portugál, Maláj, Indiai-együttműködések) | In the four-year-long research period (2008-2012) the parasitic infections of fishes and intermediate hosts of Lake Balaton and its tributaries were monitored by regular samplings. The life cycle or intraoligochaete development of several myxosporean species have been clarified using experimental and molecular methods. We achieved new results in the research on fish trematodes and their larval forms parasitizing molluscs. Our research group called the attention to the role of a parasitic copepod in the mortality of common bream population in 2009. We reported on the first occurrence of three invasive clam species in Lake Balaton. For the first time, in cooperation with our virologist colleagues, we reported circovirus infections from fishes. The majority of our new results have been published in conference materials, scientific journals and in a book chapter. Co-operative projects with foreign researchers (Portuguese, Malaysian and Indian co-operations) have also been implemented, by the financial support of the National Scientific Research Fund of Hungary (OTKA)

Threat of cercarial dermatitis in Hungary: A first report of Trichobilharzia franki from the mallard (Anas platyrhynchos) and European ear snail (Radix auricularia) using molecular methods

Cercarial dermatitis in humans is a re-emerging zoonotic disease caused by infectious larvae of avian blood flukes within the Schistosomatidae family. Upon water contact, these avian schistosome larvae directly penetrate human skin and cause irritation. Between September 2018 and September 2020, carcasses of 94 mallards (Anas platyrhynchos), two green-winged teals (Anas crecca) along with one ferruginous duck (Aythya nyroca) were examined. Birds were collected within 12 regions of Hungary, representative of 9 different counties. Inspecting both morphological characters and molecular data, the cytochrome oxidase subunit I (COI) and large subunit ribosomal DNA (LSU rDNA) sequences, Bilharziella polonica and Dendritobilharzia pulverulenta were each identified. Most importantly, Trichobilharzia franki was found for the first time in Hungary and in 5 dispersed counties in conjunction with of 3 counties where other avian schistosomes were found. Of note, these avian blood flukes were predominately encountered in wild mallards (∼50%) and not in birds reared for hunting (∼1%). In total, 245 European ear snails (Radix auricularia), a known intermediate host of Trichobilharzia spp., were collected from an urban pond in Eger, Hungary. Five snails (∼2%) consistently shed numerous furcocercariae of T. franki that were confirmed by molecular methods. Our findings help to pinpoint a contemporary life cycle of this avian schistosome within an urban environment, a location regularly visited by various wild waterfowl and the possible species of avian schistosomes responsible for cercarial dermatitis in Hungary. Taken as a whole, we demonstrate the actual and potential risk zone for cercarial dermatitis, particularly with reference to R. auricularia distributions, within Hungary and across Central Europe

Molecular biological studies of adult and metacercarial stages of Petasiger exaeretus Dietz, 1909 (Digenea: Echinostomatidae)

Molnár et al. (2015) reported two types of echinostomatid metacercariae in the lateral line organ of Hungarian fish species. Type 1 metacercariae possessed 27 collar spines and 16 uniform and three larger dorsal spines, whereas Type 2 metacercariae bore 27 collar spines and 19 equal-sized dorsal spines. In the recent work, molecular studies carried out on the ITS region and partial 28S rDNA sequences of two types of echinostomatid metacercariae and the sequences of adult stages of the species of Petasiger Dietz, 1909 collected from cormorants (Phalacrocorax carbo L.) showed that some of the Type 2 metacercariae corresponded to Petasiger exaeretus Dietz, 1909, whereas other morphologically similar metacercariae were identified as Petasiger phalacrocoracis (Yamaguti, 1939). The sequences of the Type 1 metacercariae with three larger dorsal spines could not be identified with any of the known sequences from echinostomatid trematodes

Three new species of Myxobolus Bütschli, 1882 (Myxozoa: Myxobolidae) infecting the common nase Chondrostoma nasus (L.) in the River Danube

The common nase Chondrostoma nasus (L.) is a frequent cyprinid fish in the River Danube. In a survey on its infection with myxosporeans, eight different Myxobolus spp. spore types were found in the gills, swim bladder, fins and intestinal wall. Of these, spore types representing three species were studied in detail by morphological and molecular methods. Based on the differences in 18S rDNA sequences, two new species of Myxobolus Bütschli, 1882 from the gills and one from the swim bladder are described: M. arrabonensis n. sp., M. szentendrensis n. sp. and M. paksensis n. sp. The new species resembled M. muelleri Bütschli, 1882, M. intimus Zaika, 1965 and M.cycloides Gurley, 1893, all parasitic in leuciscine cyprinids, in spore size and location in the host, but exhibited differences in partial 18S rDNA sequences as follows: M. arrabonensis - M. muelleri (1.4%), M. szentendrensis - M. intimus (2.8%), M. paksensis - M. cycloides (2.4%). Based on the significant differences in rDNA sequences, the three forms are considered to represent new, hitherto undescribed species in spite of their morphological similarities to some Myxobolus spp. forming spores in identical locations in genetically closely related cyprinids of the subfamily Leuciscinae