Parasites in harbour seals (Phoca vitulina) from the German Wadden Sea between two Phocine Distemper Virus epidemics

Abstract

Parasites were collected from 107 harbour seals (Phoca vitulina) found on the coasts of Schleswig-Holstein, Germany, between 1997 and 2000. The prevalence of the parasites and their associated pathology were investigated. Eight species of parasites, primarily nematodes, were identiWed from the examined organs: two anisakid nematodes (Pseudoterranova decipiens (sensu lato), Contracaecum osculatum (sensu lato)) from the stomach, Otostrongylus circumlitus (Crenosomatidae) and ParaWlaroides gymnurus (Filaroididae) from the respiratory tract, one Wlarioid nematode (Acanthocheilonema spirocauda) from the heart, two acanthocephalans, Corynosoma strumosum and C. semerme (Polymorphidae), from the intestine and an ectoparasite, Echinophthirius horridus (Anoplura, Insecta). Lungworm infection was the most prominent parasitological Wnding and secondary bacterial bronchopneumonia the most pathogenic lesion correlated with the parasites. Heavy nematode burdens in the respiratory tract were highly agerelated and more frequent in young seals. A positive correlation was observed between high levels of pulmonary infection and severity of bronchopneumonia. The prevalence of lungworms in this study was higher than in seals that died during the 1988/1989 Phocine Distemper Virus epidemic, and the prevalence of acanthocephalans and heartworms had decreased compared to Wndings from the Wrst die-oV.

Anisakids of seals found on the southern coast of Baltic Sea

“…In common seals there was a majority of P. decipiens. This anisakid species had been found several times in common seals of eastern Atlantic (McClelland 2002) including Oslofjord (Aspholm et al 1995) and Wadden Sea (Lehnert et al 2007), L4 and adult C. osculatum and P. decipiens numbers were equal. During the research made in Oslofjord (Aspholm et al 1995) it has been proven that L3, L4 and adult worms can be found in common seals.…”

“…The same observation has been made during this research. Occurrence of P. decipiens among the grey seals of North Sea (Aspholm et al 1995, Lehnert et al 2007) makes a possibility of finding the parasite in Baltic Sea that could migrate with the paratenic hosts. The seals living in Baltic Sea feed mainly on herrings (Lundström et al 2010) which are vectors for A. simplex (Guz et al 2005, Sinisalo 2007).…”

Heartworm (Acanthocheilonema spirocauda) and seal louse (Echinophthirius horridus) infections in harbour seals (Phoca vitulina) from the North and Baltic Seas

“…Heartworms had no apparent impact (nor associated lesions) on the health status of their hosts, although some lesions in the heart associated to A. spirocauda have been described (Dunn and Wolke, 1976;Measures et al, 1997). Seal lice can cause alopecia, skin lesions and anaemia, but only seldom induce severe lesions with resulting in a higher mortality (Conlogue et al, 1980;Lehnert et al, 2007). It can be assumed that animals suffering from severe infections of e.g.…”

Heterozygosity and lungworm burden in harbour seals (Phoca vitulina)

“…Lungworm infection is an important cause of morbidity and mortality in harbour seals, in particular in young seals (Measures, 2001;Vercruysse et al, 2003;Lehnert et al, 2007a). Lungworm infection is caused by two macroparasites (Vercruysse et al, 2003), often found concurrently (Lehnert et al, 2007a): Otostrongylus circumlitus, a large species whose adults are easily visible in the principal airways and, Parafilaroides gymnurus, a smaller species found in the alveoli and smaller bronchioles. For the analysis, we used 27 polymorphic loci genotyped in a sample of 204 harbour seals that stranded along the Dutch coast, taking into account the relationship between lungworm burden and age.…”