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Prevalence and molecular characterisation of lung nematodes of harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) (Parasite genetics)

Project data

Project leader: Dr. Kristina Lehnert

Project description

Harbour porpoises and harbour seals from German waters show mixed infections with different species of lung nematodes belonging to the superfamily Metastrongyloidea, which often induce secondary bacterial infections and bronchopneumonia. Metastrongyloids, or lungworms, infect a wide range of mammals and are usually found in the bronchi, parenchyma or blood vessels associated with the lungs. Most terrestrial metastrongylids are heteroxenous, using a mollusc as intermediate host. Little is known about the biology of metastrongyloids infecting marine mammals and their transmission in the marine environment has been poorly studied. Lungworm disease and its associated pneumonia are particularly important in the health of wild populations. Parasitic bronchopneumonia and secondary bacterial infections are a common cause of mortality in harbour porpoises and especially in young seals. To establish methods to characterise and compare the nematode species, ribosomal DNA (rDNA) is a useful tool, especially using polymerase chain reaction (PCR). The species-specific first and second Internal Transcribed Spacer (ITS-1 and ITS-2) region is known to be a variable region that separates the more conserved 18S, 5.8S and 28S regions and has been used to investigate the relationship among a variety of species including insects, cestodes, trematodes and nematodes. Genomic DNA from individual nematodes is isolated and ribosomal ITS of the lungworm species are amplified by PCR using primers designed from the adjacent conserved 18S, 5.8S and 28S regions of Caenorhabditis elegans. PCR products are sequenced and the nucleotide sequences are then edited and aligned using DNAstar software. The sequences are used to demonstrate phylogenetic relationships between the species and understand inter- and intraspecific variation amongst them. Another aim is to find out if parasite populations differ in their pathogenicity, because it remains unclear why porpoises from Norwegian waters, for example, are less affected by lungworms and associated disease than porpoises from the German North and Baltic Seas. Contrary to harbor porpoise lungworm infection in seals is  highly age-related and occurs mostly in young seals up to 1.5 years old. Investigations of possible intermediate hosts might show if the life-cycle of these nematodes is indeed direct through transplacental infection or through lactation as previous studies have indicated, or if prey species play a role in their transmission.

Contact person

University of Veterinary Medicine Hannover, Foundation Institute for Terrestrial and Aquatic Wildlife Research Werftstr. 6 25761 Büsum


Dr. Kristina Lehnert

Tel.:+49 511 856-8171

Fax.:+49 511 856-8181


send e-mail

Stiftung Tierärztliche Hochschule Hannover
Institute for Terrestrial and Aquatic Wildlife Research
Werftstr. 6
25761 Büsum
Tel.:+49 511 856-8171
Fax.:+49 511 856-8181
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