Multiple transatlantic incursions of highly pathogenic avian influenza clade 2.3.4.4b A(H5N5) virus into North America and spillover to mammals.

Highly pathogenic avian influenza (HPAI) viruses have spread at an unprecedented scale, leading to mass mortalities in birds and mammals. In 2023, a transatlantic incursion of HPAI A(H5N5) viruses into North America was detected, followed shortly thereafter by a mammalian detection. As these A(H5N5) viruses were similar to contemporary viruses described in Eurasia, the transatlantic spread of A(H5N5) viruses was most likely facilitated by pelagic seabirds.

Investigation, management and control of a maedi outbreak in Norway in 2019-2020.

Background: Visna-maedi is a notifiable disease in Norway, and eliminating the disease is a national goal. The import of sheep into Norway is very limited, and strict regulations apply to the movement of small ruminants between flocks and within defined geographical regions. Several outbreaks have occurred in the last 50 years, and the most recent before 2019 occurred in Trøndelag county in Central Norway in 2002.

Development of a Bead-Based Multiplex Fluorescent Immunoassay to Detect Antibodies against Maedi-Visna Virus in Sheep.

The Maedi-visna virus (MVV) causes a persistent infection in small ruminants, and its high genetic heterogeneity affects the performance of diagnostic tests when used in different populations. Therefore, the aim of this study was to develop a bead-based multiplex immunoassay tailored to detect antibodies against a Norwegian MVV strain. We used tissue samples from 14 PCR-positive sheep from a recent MVV outbreak in Norway to sequence the viral strain and produced recombinant antigens based on sequences from one animal.

High pathogenic avian influenza A(H5) viruses of clade 2.3.4.4b in Europe-Why trends of virus evolution are more difficult to predict.

Since 2016, A(H5Nx) high pathogenic avian influenza (HPAI) virus of clade 2.3.4.

Susceptibility and Pathology in Juvenile Atlantic Cod to a Marine Viral Haemorrhagic Septicaemia Virus Isolated from Diseased Rainbow Trout .

The first known outbreak caused by a viral haemorrhagic septicaemia virus (VHSV) strain of genotype III in rainbow trout occurred in 2007 at a marine farm in Storfjorden, Norway. The source of the virus is unknown, and cod and other marine fish around the farms are suspected as a possible reservoir. The main objective of this study was to test the susceptibility of juvenile Atlantic cod to the VHSV isolate from Storfjorden.

An Official Outbreak Investigation of Acute Haemorrhagic Diarrhoea in Dogs in Norway Points to as a Likely Cause.

An outbreak investigation was initiated in September 2019, following a notification to the Norwegian Food Safety Authority (NFSA) of an unusually high number of dogs with acute haemorrhagic diarrhoea (AHD) in Oslo. Diagnostic testing by reporting veterinarians had not detected a cause. The official investigation sought to identify a possible common cause, the extent of the outbreak and prevent spread.

First detection of highly pathogenic avian influenza virus in Norway.

Background: Several outbreaks of highly pathogenic avian influenza (HPAI) caused by influenza A virus of subtype H5N8 have been reported in wild birds and poultry in Europe during autumn 2020. Norway is one of the few countries in Europe that had not previously detected HPAI virus, despite widespread active monitoring of both domestic and wild birds since 2005.

Results: We report detection of HPAI virus subtype H5N8 in a wild pink-footed goose (Anser brachyrhynchus), and several other geese, ducks and a gull, from south-western Norway in November and December 2020.

Bovine respiratory syncytial virus in experimentally exposed and rechallenged calves; viral shedding related to clinical signs and the potential for transmission.

Background: Bovine respiratory syncytial virus (BRSV) is an important respiratory pathogen worldwide, detrimentally affecting the economy and animal welfare. To prevent and control BRSV infection, further knowledge on virus shedding and transmission potential in individual animals is required. This study aimed to detect viral RNA and infective virions during BRSV infection to evaluate duration of the transmission period and correlation with clinical signs of disease.

Temporary carriage of bovine coronavirus and bovine respiratory syncytial virus by fomites and human nasal mucosa after exposure to infected calves.

Background: In order to prevent spread of the endemic pathogens bovine coronavirus (BCoV) and bovine respiratory syncytial virus (BRSV) between herds, knowledge of indirect transmission by personnel and fomites is fundamental. The aims of the study were to determine the duration of viral RNA carriage and the infectivity of viral particles on fomites and human nasal mucosa after exposure to BCoV and BRSV. During two animal infection experiments, swabs were collected from personnel (nasal mucosa) and their clothes, boots and equipment after contact with calves shedding either virus.

Human to animal transmission of influenza A(H1N1)pdm09 in a turkey breeder flock in Norway.

: Routine surveillance samples disclosed seropositivity to influenza A virus (IAV) in a Norwegian turkey breeder flock. Simultaneous reports of influenza-like symptoms in farm workers and a laboratory confirmed influenza A(H1N1)pdm09 (H1N1pdm09) infection in one person led to the suspicion of a H1N1pdm09 infection in the turkeys. : H1N1pdm09 infection was confirmed by a positive haemaggutinin inhibition test using H1N1pdm09 antigens, and detection of H1N1pdm09 nucleic acid in reproductive organs of turkey hens.

Screening for viral hemorrhagic septicemia virus in marine fish along the Norwegian coastal line.

Viral hemorrhagic septicemia virus (VHSV) infects a wide range of marine fish species. To study the occurrence of VHSV in wild marine fish populations in Norwegian coastal waters and fjord systems a total of 1927 fish from 39 different species were sampled through 5 research cruises conducted in 2009 to 2011. In total, VHSV was detected by rRT-PCR in twelve samples originating from Atlantic herring (Clupea harengus), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and silvery pout (Gadiculus argenteus).

Swine influenza in Norway: a distinct lineage of influenza A(H1N1)pdm09 virus.

Background: Since the influenza A(H1N1)pdm09 virus was first introduced to the Norwegian pig population in September 2009, it has repeatedly been detected in pigs in Norway. No other subtypes of influenza virus are circulating in Norwegian pigs.

Objective: To follow the diversity of A(H1N1)pdm09 viruses circulating in pigs in Norway and to investigate the relationship between viruses circulating in Norwegian pigs and in humans.

Multiple introductions of salmonid alphavirus from a wild reservoir have caused independent and self-sustainable epizootics in aquaculture.

Salmonid alphavirus (SAV) causes infections in farmed Atlantic salmon and rainbow trout in Europe. Genetic diversity exists among SAV strains from farmed fish and six subtypes have been proposed based on genetic distance. Here, we used six full-genome sequences and 71 partial sequences of the structural ORF to estimate the evolutionary rate of SAV.

Influenza A(H1N1)pdm09 virus infection in Norwegian swine herds 2009/10: the risk of human to swine transmission.

Influenza A viruses cause respiratory infection in humans and pigs, and some serotypes can be transmitted between these species. The emergence of influenza A(H1N1)pdm09 virus infections in the spring of 2009 quickly led to a worldwide pandemic in humans, with subsequent introduction of the virus to pig populations. Following a widespread infection in the human population in Norway, influenza A(H1N1)pdm09 virus was introduced to the influenza A naïve Norwegian pig population, and within a few months pigs in more than one third of Norwegian swine herds had antibodies against the virus.

Pathological Findings and Distribution of Pandemic Influenza A (H1N1) 2009 Virus in Lungs from Naturally Infected Fattening Pigs in Norway.

The Norwegian pig population was considered free from influenza A virus infections until the first case of porcine pandemic influenza A (H1N1) 2009 virus infection in October 2009. Human to pig transmission of virus was suspected. Unusual lung lesions were observed in fattening pigs, with red, lobular, multifocal to coalescing consolidation, most frequently in the cranial, middle, and accessory lobes.

Clinical Impact of Infection with Pandemic Influenza (H1N1) 2009 Virus in Naïve Nucleus and Multiplier Pig Herds in Norway.

The Norwegian pig population has been free from influenza viruses until 2009. The pandemic influenza outbreak during the autumn 2009 provided an opportunity to study the clinical impact of this infection in an entirely naïve pig population. This paper describes the results of a case-control study on the clinical impact of pandemic influenza (H1N1) 2009 infection in the nucleus and multiplier herds in Norway.

Molecular epidemiology of salmonid alphavirus (SAV) subtype 3 in Norway.

Background: Pancreas disease (PD) is a viral fish disease which in recent years has significantly affected Norwegian salmonid aquaculture. In Norway, the aetiological agent salmonid alphavirus (SAV) has been found to be represented by the subtype 3 only. SAV subtype 3 has in previous analyses been found to show a lower genetic divergence than the subtypes found to cause PD in Ireland and Scotland.

Impact of natural sheep-goat transmission on detection and control of small ruminant lentivirus group C infections.

Dissemination of small ruminant lentivirus (SRLV) infections in Norway is affected by the different control strategies used for maedi-visna virus (MVV) infections in sheep and caprine arthritis-encephalitis virus (CAEV) infections in goats. Here we investigated SRLV phylogenetic group variants in sheep. CAEV-like isolates, belonging to phylogenetic group C, were found among both seropositive sheep and goats in mixed flocks, in which sheep and goats are kept together.

Natural transmission and comparative analysis of small ruminant lentiviruses in the Norwegian sheep and goat populations.

Serological surveys for small ruminant lentivirus (SRLV) infections have revealed seropositive sheep in several mixed herds, where sheep are kept together with seropositive goats. Here we have examined the genetic relationships in LTR, pol and env surface unit (SU) and the growth patterns in goat (GSM) and sheep (FOS) synovial membrane cell cultures of SRLV isolates obtained from both mixed and single species herds. Phylogenetic analyses of pol and env SU revealed that Norwegian SRLVs derived from both goat and sheep in mixed herds are distributed into group C, while isolates obtained from unmixed sheep flocks cluster in group A, together with maedi-visna-like representatives of the A1 subtype.

Genetic diversity of small-ruminant lentiviruses: characterization of Norwegian isolates of Caprine arthritis encephalitis virus.

Small-ruminant lentiviruses (SRLVs), including Caprine arthritis encephalitis virus (CAEV) in goats and maedi-visna virus (MVV) in sheep, are lentiviruses that, despite overall similarities, show considerable genetic variation in regions of the SRLV genome. To gain further knowledge about the genetic diversity and phylogenetic relationships among field isolates of SRLVs occurring in geographically distinct areas, the full-length genomic sequence of a CAEV isolate (CAEV-1GA) and partial env sequences obtained from Norwegian CAEV-infected goats were determined. The genome of CAEV-1GA consisted of 8,919 bp.