Characterization of the heartworm Acanthocheilonema spirocauda (Leidy, 1858) Anderson, 1992 (Nematoda: Onchocercidae) in Scandinavia

et al. 2021

Preprint

Background: Belonging to the anopluran family Echinophthiriidae, Echinophthirius horridus, the seal louse, has been reported to parasitize a broad range of representatives of phocid seals. So far, only few studies focused on vector function of echinophthiriid lice and knowledge on their role in pathogen transmission is still scarce. The current study aims to investigate the possible vector role of E. horridus parasitizing seals in the Dutch Wadden Sea.Methods: E. horridus seal lice were collected from 54 harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) during their rehabilitation period at the Sealcentre Pieterburen, the Netherlands. DNA was extracted from pooled seal lice of individual seals for molecular detection of the seal heartworm Acanthocheilonema spirocauda, the rickettsial intracellular bacterium Anaplasma phagocytophilum, and the cell wall-less bacteria Mycoplasma spp. using PCR assays.Results: Seal lice from 35% of the harbour seals (19/54) and from the grey seal proved positive for A. spirocauda. The seal heartworm was molecularly characterised and phylogenetically analysed (rDNA, cox1). A nested PCR was developed for the cox1 gene to detect A. spirocauda stages in seal lice. A. phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated ‘seal finger’ mycoplasmosis were detected the first time in seal lice. Conclusions: Our findings support the potential vector role of seal lice in transmission of A. spirocauda, and reveal new insights into the spectrum of pathogens occurring in seal lice. Studies on vector competence of E. horridus, especially for bacterial pathogens, are essentially needed in the future as these pathogens might have detrimental effects on the health of seal populations. Further, studies on the vector role of different echinophthiriid species infecting a wide range of pinniped hosts should be conducted to extend the knowledge of vector borne pathogens in seal lice.

Section: Pcr Analysesmentioning

confidence: 99%

The seal louse (Echinophthirius horridus) in the Dutch Wadden Sea: investigation of vector-borne pathogens

et al. 2021

Preprint

“…Before this survey started no molecular data were available from the lariae A. spirocauda. We morphologically con rmed adult parasites according to Leidenberger and Boström [35] (see Additional le 2), extracted DNA and deposited the rst sequences of the ribosomal region (ITS1, 5.8S, ITS2, and partial 28S) and the cox1 gene into NCBI GenBank database. Phylogenetic analysis of the partial cox1 sequence shows the closest relation of A. spirocauda to A. odendhali (Fig.…”

Section: Phylogenetic Analysis Of a Spirocauda And The Mycoplasma Ismentioning

confidence: 99%

The Seal Louse (Echinophthirius horridus) in the Dutch Wadden Sea: Investigation of Vector-Borne Pathogens and Morphological Adaptations

et al. 2020

Preprint

Background: Belonging to the anopluran family Echinophthiriidae, Echinophthirius horridus, the seal louse, has been reported to parasitize a broad range of representatives of phocid seals. So far, only few studies focused on vector function of echinophthiriid lice and knowledge on their role in pathogen transmission is still scarce. The current study aims to investigate the role of E. horridus in vector-borne diseases of seals in the Dutch Wadden Sea and to attribute to its morphological features of environmental adaptation.Methods: More than 1200 E. horridus seal lice were collected from 54 harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) during their rehabilitation period in the Sealcentre Pieterburen, the Netherlands. DNA was extracted from pooled seal lice of individual seals for molecular detection of the seal heartworm Acanthocheilonema spirocauda, the rickettsial intracellular bacterium Anaplasma phagocytophilum, and Mycoplasma spp. using PCR assays. In addition E. horridus-adult and -eggs were analysed by scanning electron microscopy (SEM).Results: Seal lice from 35% of the harbour seals (19/54) and from the grey seal proved positive for A. spirocauda. The seal heartworm was molecularly characterised and phylogenetically analysed for the first time (rDNA, cox1). A nested PCR was developed for the cox1 gene to detect A. spirocauda stages in seal lice. A. phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated ‘seal finger’ mycoplasmosis were detected the first time in seal lice. SEM analyses of E. horridus-adults and -eggs brought out more clearly unique morphological features, such as ‘lock-like’ claws, setae-covered cuticle as well as vaulted nit lids carrying micropyles for respiration, which all demonstrate the adaption of this ectoparasite to its semiaquatic host and the marine environment.Conclusions: Our findings support the vector role of seal lice in transmission of A. spirocauda, Mycoplasma spp. and A. phagocytophilum and presented more detailed images of their morphological adaptations to the semiaquatic lifestyle of their hosts. As the vector-borne pathogens might have detrimental effects on the health of seal populations further epidemiological investigations on infections due to these pathogens in seals should be conducted.

“…The cox1-sequence from one seal lice pool was submitted to GenBank (accession number HG005138). To validate the sequences from the lice pools and to obtain further sequences from A. spirocauda, we then extracted DNA from morphologically con rmed A. spirocauda adult nematodes (identi ed according to Leidenberger and Boström [25]; please see Additional le 2), which were collected from necropsied harbour seals at Sealcentre Pieterburen between 2009-2011. Further, we ampli ed, sequenced and assembled a partial sequence of the ribosomal DNA region (ITS1, 5.8S, ITS2, and partial 28S) using primers NC5/NC2 [26] and the above-mentioned cox1-primers.…”

Section: Introductionmentioning

confidence: 99%

The seal louse (Echinophthirius horridus) in the Dutch Wadden Sea: investigation of vector-borne pathogens 

et al. 2020

Preprint

Background: Belonging to the anopluran family Echinophthiriidae, Echinophthirius horridus, the seal louse, has been reported to parasitize a broad range of representatives of phocid seals. So far, only few studies focused on vector function of echinophthiriid lice and knowledge on their role in pathogen transmission is still scarce. The current study aims to investigate the possible vector role of E. horridus parasitizing seals in the Dutch Wadden Sea.Methods: More than 1200 E. horridus seal lice were collected from 54 harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) during their rehabilitation period in the Sealcentre Pieterburen, the Netherlands. DNA was extracted from pooled seal lice of individual seals for molecular detection of the seal heartworm Acanthocheilonema spirocauda, the rickettsial intracellular bacterium Anaplasma phagocytophilum, and Mycoplasma spp. using PCR assays.Results: Seal lice from 35% of the harbour seals (19/54) and from the grey seal proved positive for A. spirocauda. The seal heartworm was molecularly characterised and phylogenetically analysed for the first time (rDNA, cox1). A nested PCR was developed for the cox1 gene to detect A. spirocauda stages in seal lice. A. phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated ‘seal finger’ mycoplasmosis were detected the first time in seal lice. Conclusions: Our findings support the potential vector role of seal lice in transmission of A. spirocauda, and reveal new insights into the spectrum of pathogens occurring in seal lice. As these pathogens might have detrimental effects on the health of seal populations further epidemiological investigations on infections due to these pathogens in seals should be conducted.