https://phaidra.vetmeduni.ac.at/o:2074 Novel 3D in situ visualization of seal heartworm (Acanthocheilonema spirocauda) larvae in the seal louse (Echinophthirius horridus) by X-ray microCT Ebmer, David David Ebmer Justus Liebig University Giessen Hermosilla, Carlos Carlos Hermosilla Justus Liebig University Giessen Taubert, Anja Anja Taubert Justus Liebig University Giessen Glösmann, Martin Martin Glösmann 0000-0002-2094-3247 University of Veterinary Medicine Vienna Gärtner, Ulrich Ulrich Gärtner Justus Liebig University Giessen Rubio-García, Ana Ana Rubio-García Sealcentre Pieterburen Schwaha, Thomas Thomas Schwaha University of Vienna Handschuh, Stephan Stephan Handschuh 0000-0002-2140-7892 University of Veterinary Medicine Vienna Nature Portfolio text eng The seal heartworm Acanthocheilonema spirocauda (Nematoda: Onchocercidae) parasitizes the heart and pulmonary arteries of various phocid seals of the Northern Hemisphere. Over many decades, potential vectors of this parasite have been discussed, and to this date, the life cycle is not fully known. The seal louse Echinophthirius horridus (Anoplura: Echinophthiriidae) is an obligatory, permanent and haematophagous ectoparasite of phocids that has been hypothesized to function as obligate intermediate host for A. spirocauda. We examined 11 adult E. horridus specimens collected from stranded harbour seals (Phoca vitulina) in rehabilitation at the Sealcentre Pieterburen by X-ray microCT imaging, aiming to illustrate larval A. spirocauda infection sites in situ. In three of these specimens, thread-like larvae were detected in insect organs. Detailed imaging of the most infected louse revealed a total of 54 A. spirocauda larvae located either in fat bodies or the haemocoel. Histological analysis of the same specimen illustrated nematode cross-sections, confirming X-ray microCT data. The current data strongly suggest that E. horridus is a natural intermediate host for A. spirocauda. Moreover, we demonstrate the potential of X-ray microCT-based imaging as a non-destructive method to analyze host-parasite interactions, especially in the neglected field of marine mammal parasitology. Acanthocheilonema; Animals; Anoplura; Dirofilaria immitis; Larva; Nematoda; Phoca; X-Ray Microtomography http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:2074/download 10.1038/s41598-022-18418-y https://phaidra.vetmeduni.ac.at/o:605 application/pdf Scientific Reports 12(1) (2022) Scientific Reports 12 1 1.02 MB 2022