In 1988 and 2002, two major phocine distemper virus (PDV) outbreaks occurred in harbour seals (Phoca vitulina) in north-western European coastal waters, causing the death of tens of thousands seals. Here we investigated whether PDV is still circulating among seals of the Dutch coastal waters and whether seals have protective serum-antibodies against PDV. Therefore seal serum samples, collected from 2002 to 2012, were tested for the presence of PDV-neutralizing antibodies. Antibodies were detected in most seals in 2002 and 2003 while after 2003 antibodies were detected only in seals less than two month-old and adult seals that probably had survived the 2002 PDV-epizootic. We estimated the current proportion of seals with antibodies against PDV at 11%. These findings suggest that at present the vast majority of seals are not immune to PDV infection. PDV re-introduction in this area may cause a major epizootic with infection of >80% and mass-mortality of >50% of the population.

Using random PCR in combination with next-generation sequencing, a novel parvovirus was detected in the brain of a young harbor seal (Phoca vitulina) with chronic non-suppurative meningo-encephalitis that was rehabilitated at the Seal Rehabilitation and Research Centre (SRRC) in the Netherlands. In addition, two novel viruses belonging to the family Anelloviridae were detected in the lungs of this animal. Phylogenetic analysis of the coding sequence of the novel parvovirus, tentatively called Seal parvovirus, indicated that this virus belonged to the genus Erythrovirus, to which human parvovirus B19 also belongs. Although no other seals with similar signs were rehabilitated in SRRC in recent years, a prevalence study of tissues of seals from the same area collected in the period 2008-2012 indicated that the Seal parvovirus has circulated in the harbor seal population at least since 2008. The presence of the Seal parvovirus in the brain was confirmed by real-time PCR and in vitro replication. Using in situ hybridization, we showed for the first time that a parvovirus of the genus Erythrovirus was present in the Virchow-Robin space and in cerebral parenchyma adjacent to the meninges. These findings showed that a parvovirus of the genus Erythrovirus can be involved in central nervous system infection and inflammation, as has also been suspected but not proven for human parvovirus B19 infection.

Five white-beaked dolphins Lagenorhynchus albirostris with outwardly vertebral kyphosis, kyphoscoliosis or lordosis were identified during a photo-identification survey of over 400 individuals (2002-2013) in Faxaflói and Skjálfandi Bays, Iceland. In addition, 3 stranding reports from Denmark, The Netherlands and the UK were analysed, providing both external observation and post mortem details of axial deviations of the vertebral column in this species. Two of the free-ranging cases and 2 of the stranded specimens appeared to have an acquired disease, either as a direct result of trauma, or indirectly from trauma/wound and subsequent infection and bony proliferation, although we were unable to specifically identify the causes. Our data represent a starting point to understand vertebral column deformations and their implications in white-beaked dolphins from the eastern North Atlantic. We recommend for future necropsy cases to conduct macro- and microscopic evaluation of muscle from both sides of the deformed region, in order to assess chronic or acute conditions related to the vertebral deformations and cause of death.

No abstract

A novel parvovirus was discovered recently in the brain of a harbor seal (Phoca vitulina) with chronic meningo-encephalitis. Phylogenetic analysis of this virus indicated that it belongs to the genus Erythroparvovirus, to which also human parvovirus B19 belongs. In the present study, the prevalence, genetic diversity and clinical relevance of seal parvovirus (SePV) infections was evaluated in both harbor and grey seals (Halichoerus grypus) that lived in Northwestern European coastal waters from 1988 to 2014. To this end, serum and tissue samples collected from seals were tested for the presence of seal parvovirus DNA by real-time PCR and the sequences of the partial NS gene and the complete VP2 gene of positive samples were determined. Seal parvovirus DNA was detected in nine (8%) of the spleen tissues tested and in one (0.5%) of the serum samples tested, including samples collected from seals that died in 1988. Sequence analysis of the partial NS and complete VP2 genes of nine SePV revealed multiple sites with nucleotide substitutions but only one amino acid change in the VP2 gene. Estimated nucleotide substitution rates per year were 2.00×10−4 for the partial NS gene and 1.15×10−4 for the complete VP2 gene. Most samples containing SePV DNA were co-infected with phocine herpesvirus 1 or PDV, so no conclusions could be drawn about the clinical impact of SePV infection alone. The present study is one of the few in which the mutation rates of parvoviruses were evaluated over a period of more than 20 years, especially in a wildlife population, providing additional insights into the genetic diversity of parvoviruses.

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.

In 2012, 543 harbor seals (Phoca vitulina) and 124 grey seals (Halichoerus grypus) were admitted to the Seal Rehabilitation and Research Centre in Pieterburen, The Netherlands. In 19 seals (3%), signs of infection in a hind flipper were observed. Initial treatment consisting of antibiotics and anti-inflammatory drugs resolved the symptoms in 15 animals. In four harbor seals, estimated to be 3 to 4 mo old, a necrotizing infection developed that resulted in osteoarthritis of the tarsus or tibiotarsal joint or both. Bacterial culture revealed the presence of polymicrobial infection in three of the four animals. Treatment consisted of amputation of the hind flipper under general anesthesia combined with tumescent anesthesia in the operation field. Amputations were done at the diaphysis of the tibia and fibula. After resecting these bones, the flipper was discarded, leaving a good muscle-skin cuff to cover the edges of the bones and close the skin without tension. The estimated blood loss varied between <50 to 150 ml. Healing was uneventful, and both antibiotics and analgesics were gradually reduced according to the individual response. The seals did not show any functional impairment 1 mo postoperatively. After release to the sea, scrutinous revision of all radiographs showed signs of osteomyelitis in at least one animal in the proximal part of the tibia, also present preoperatively. It is concluded that tumescent anesthesia in seals may reduce perioperative blood loss and that a lower leg amputation is a surgically easy and clean approach for the treatment of osteoarthritis of the hind flipper of seals, giving good functional results (diving, catching fish, exiting a pool, and moving on land).

Offshore exploration in Colombia is in its initial stage. Currently, only few studies of acute and chronic toxicity with marine organisms evaluate drilling muds. In this paper, we test acute and chronic toxicity in juvenile organisms of Argopecten nucleus exposed to water and synthetic based muds. Aim is establish lethal median concentration (LC50) to 96 h and effects on survival and growth (height and weight) for a 30 d period. In acute tests, three water based muds (E2-LBA, E2-LBA-2 y E3-LBA-2) are below the minimal value established by EPA (1993) to be discharged in the marine environment. Given the value of the non observable effect concentration (NOEC), samples were ordered in increasing order, E3-WBM-2 < E1-SBM-2 < E1-WBM < E3-SBM-2. According to classifiation established by GESAMP (2002), all drilling muds evaluated from acute and chronic tests are nontoxic or with negligible toxicity, respectively. This results are the fist ones in Colombia using a bivalve specie in acute and chronic toxicity tests exposed to drilling muds.