Avian influenza overview August - November2019

Between 16 August and 15 November 2019, one low pathogenic avian influenza (LPAI) A(H5) outbreak in poultry in France was reported in Europe. Genetic characterisation reveals that the virusclusterswith Eurasian LPAI viruses. No highly pathogenic avian influenza (HPAI) outbreaks in birds were notified in Europe in the relevant period for this report. HPAI A(H5N6) viruswas identified in chickens in Nigeria, this isthe first report of HPAI A(H5N6) from the African continent.FewerHPAI outbreaks in Asia and Africa were reported during the time period for this report compared with the previous reporting period. Apart from the long‐term epidemic of HPAI A(H5N2)in Taiwan, only six HPAI outbreakswere reported in domestic birds from Nepal, South Africa and Taiwan. Furthermore, no HPAI detections fromwild birds were reported worldwide in the relevant time period forthis report.Even if the risk of incursion of HPAI from wild birds into poultryestablishments in Europe is currently assessed as low, it is important to maintain passive surveillance activities. The focus should be on wild bird species that are in the revised list of target species in order to detect any incursion of HPAI virus early and initiate a warning.Despite the decrease in the number of avian influenza outbreaks over recent months, it is important to maintain a high alert level andhigh standard of biosecurity onpoultry establishments.In Europe, no human infections due toHPAI viruses detected in wild bird or poultry outbreaks, have been reported. The risk of zoonotic transmission to the general public in Europe is considered to be very low.

Avian influenza overview February - May 2020

Between 16 February and 15 May 2020, 290highly pathogenic avian influenza (HPAI) A(H5) virus outbreakswere reported in Europe in poultry (n=287), captive birds (n=2) and wild birds (n=1)in Bulgaria, Czechia,Germany,Hungary andPolandand two low pathogenic avian influenza (LPAI) A(H7N1) virus outbreaks were reported in poultry in Italy. 258 of 287 poultry outbreaks detected in Europe were secondary outbreaks, suggesting that in the large majoryty of cases the spread of the virus was not due to wild birds.Allthe HPAI outbreaks were A(H5N8) apart from three,which were reported as A(H5N2) from Bulgaria. Genetic analysis of the HPAI A(H5N8) viruses isolated from the eastern and central European countries indicates that this is a reassortant between HPAI A(H5N8) viruses from Africa and LPAI viruses from Eurasia. Two distict subtypes were identified in Bulgaria, a novel reassortant A(H5N2) and A(H5N8) that is persisting in the country since 2016. There could be several reasons why only very few HPAI cases were detected in wild birds in this 2019-2020 epidemic season and a better knowledge of wild bird movements and virus-host interaction (e.g. susceptibility of the hosts to this virus) could help to understand the reasons for poor detection of HPAI infected wild birds. In comparison with the last reporting period, a decreasing number of HPAI A(H5)-affected countries and outbreaks were reported from outside Europe. However, there is considerable uncertainty regarding the current epidemiological situation in many countries out of Europe. Four human cases due to A(H9N2) virus infection were reported during the reporting period from China.

Comparative pathogenesis of COVID-19, MERS, and SARS in a nonhuman primate model

The current pandemic coronavirus, severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), was recently identified in patients with an acute respiratory syndrome, coronavirus disease 2019 (COVID-19). To compare its pathogenesis with that of previously emerging coronaviruses, we inoculated cynomolgus macaques with SARS-CoV-2 or Middle East respiratory syndrome (MERS)-CoV and compared the pathology and virology with historical reports of SARS-CoV infections. In SARS-CoV-2-infected macaques, virus was excreted from nose and throat in the absence of clinical signs and detected in type I and II pneumocytes in foci of diffuse alveolar damage and in ciliated epithelial cells of nasal, bronchial, and bronchiolar mucosae. In SARS-CoV infection, lung lesions were typically more severe, whereas they were milder in MERS-CoV infection, where virus was detected mainly in type II pneumocytes. These data show that SARS-CoV-2 causes COVID-19-like disease in macaques and provides a new model to test preventive and therapeutic strategies.

Avian influenza overview November 2019- February2020

Between 16 November 2019 and 15 February 2020, 36 highly pathogenic avian influenza (HPAI) A(H5N8) virus outbreakswere reported in Europe in poultry (n=34), captive birds (n=1) and wild birds (n=2), in Poland, Hungary, Slovakia, Romania, Germany, Czechiaand Ukraine,one HPAI outbreakcaused by a simultaneous infection with A(H5N2) and A(H5N8) was reported in poultry in Bulgaria, andtwo low pathogenic avian influenza (LPAI) A(H5) virus outbreaks were reported in poultryin the United Kingdom and in Denmark. Genomic characterisation of the HPAI A(H5N8) viruses suggests that they are reassortants of HPAI A(H5N8) viruses from Africa and LPAI viruses from Eurasia. It is likely that this reassortment occurred in wild migratory birds in Asia during the summer and then spread to eastern Europe with the autumnmigration. This is the first time that wild bird migration from Africa to Eurasia has been implicated in the long-distance spread of HPAI viruses to the EU. Given the late incursion of HPAI A(H5N8) virus into the EU in this winter season (first outbreak reported on 30 December 2019), its overall restriction to eastern Europe, and the approaching spring migration, the risk of the virus spreadingfurther in the west via wild birds is decreasing for the coming months. Genetic analysis of the HPAI A(H5N2) and A(H5N8) viruses detected in the Bulgarian outbreak reveals that these virusesare both related to the 2018-19 Bulgarian HPAI A(H5N8) viruses and not to the HPAI A(H5N8) viruses currently circulating in Europe.An increasing number of HPAI A(H5N1), A(H5N2), A(H5N5) and A(H5N6) virus outbreaks in poultry in Asia were reported during the time period for this report compared with the previous reporting period. Single outbreaks of HPAI A(H5N8) virus were notified by Saudi Arabia and South Africa. Furthermore, in contrast to the last report, HPAI virus-positive wild birds were reported from Israel and one of the key migration areas in northern China.Two human cases due to A(H9N2) virus infection were reported during the reporting period.

An evolutionary divergent pestivirus lacking the Npro gene systemically infects a whale species

Pestiviruses typically infect members of the order Artiodactyla, including ruminants and pigs, although putative rat and bat pestiviruses have also been described. In the present study, we identified and characterized an evolutionary divergent pestivirus in the toothed whale species, harbour porpoise (Phocoena phocoena). We tentatively named the virus Phocoena pestivirus (PhoPeV). PhoPeV displays a typical pestivirus genome organization except for the unique absence of N^pro, an N-terminal autoprotease that targets the innate host immune response. Evolutionary evidence indicates that PhoPeV emerged following an interspecies transmission event from an ancestral pestivirus that expressed N^pro. We show that 9% (n = 10) of stranded porpoises from the Dutch North Sea coast (n = 112) were positive for PhoPeV and they displayed a systemic infection reminiscent of non-cytopathogenic persistent pestivirus infection. The identification of PhoPeV extends the host range of pestiviruses to cetaceans (dolphins, whales, porpoises), which are considered to have evolved from artiodactyls (even-toed ungulates). Elucidation of the pathophysiology of PhoPeV infection and N^pro unique absence will add to our understanding of molecular mechanisms governing pestivirus pathogenesis.

Annual Report on surveillance for avian influenza in poultry and wild birds in Member States of the European Union in 2018

Avian influenza (AI) is a viral infectious disease that affects all species of domestic and wild birds. The viruses causing this disease can be of high (HPAI) or low (LPAI) pathogenicity and represent a continuous threat to poultry in Europe. Council Directive 2005/94/EC requests EU Member States (MSs) to carry out surveillance in poultry and wild birds and notify the results to the responsible authority. Therefore, MSs and Switzerland have implemented surveillance programmes to yearly monitor incursions of AI viruses in poultry and wild birds. EFSA received a mandate from the European Commission, to collate, validate, analyse and summarise in an annual report the data resulting from the avian influenza surveillance programmes. This is the first report produced under this mandate summarising the results of the surveillance activities carried out in poultry and wild birds in 2018. Overall 18,596 poultry establishments were sampled, of which 43 were seropositive for H5 AI and two for H7 AI. Seropositive establishments were found in 11 MSs, with the highest percentage of seropositive establishments being found in waterfowl gamebird, and geese and duck breeding establishments. A total of 9,145 dead/moribund wild birds were sampled, with 163 birds testing positive to HPAI virus H5N6. The infected birds were reported by eight MSs and were mostly found between January and April 2018. In this report, the wild bird species affected with HPAI are described and the strategy of targeted sampling is assessed. The crude odds ratio of HPAI detection as a function of the target species (species belonging to the list of target species versus species not belonging to the target list) is presented. The surveillance findings for poultry and wild birds for 2018 are also discussed in relation to findings from previous years and current knowledge on the epidemiology of AI in Europe.

Faeces as a novel material to estimate lyssavirus prevalence in bat populations

Rabies is caused by infection with a lyssavirus. Bat rabies is of concern for both public health and bat conservation. The current method for lyssavirus prevalence studies in bat populations is by oral swabbing, which is invasive for the bats, dangerous for handlers, time-consuming and expensive. In many situations, such sampling is not feasible, and hence, our understanding of epidemiology of bat rabies is limited. Faeces are usually easy to collect from bat colonies without disturbing the bats and thus could be a practical and feasible material for lyssavirus prevalence studies. To further explore this idea, we performed virological analysis on faecal pellets and oral swabs of seven serotine bats (Eptesicus serotinus) that were positive for European bat 1 lyssavirus in the brain. We also performed immunohistochemical and virological analyses on digestive tract samples of these bats to determine potential sources of lyssavirus in the faeces. We found that lyssavirus detection by RT-qPCR was nearly as sensitive in faecal pellets (6/7 bats positive, 86%) as in oral swabs (7/7 bats positive, 100%). The likely source of lyssavirus in the faeces was virus excreted into the oral cavity from the salivary glands (5/6 bats positive by immunohistochemistry and RT-qPCR) or tongue (3/4 bats positive by immunohistochemistry) and swallowed with saliva. Virus could not be isolated from any of the seven faecal pellets, suggesting the lyssavirus detected in faeces is not infectious. Lyssavirus detection in the majority of faecal pellets of infected bats shows that this novel material should be further explored for lyssavirus prevalence studies in bats.

Clinical, pathological, and laboratory diagnoses of diseases of harbour porpoises (Phocoena phocoena), live stranded on the Dutch and adjacent coasts from 2003 to 2016

Harbour porpoises (Phocoena phocoena) in the North Sea live in an environment heavily impacted by humans, the consequences of which are a concern for their health. Autopsies carried out on stranded harbour porpoises provide an opportunity to assess health problems in this species. We performed 61 autopsies on live-stranded harbour porpoises, which died following admission to a rehabilitation centre between 2003 and 2016. The animals had stranded on the Dutch (n = 52) and adjacent coasts of Belgium (n = 2) and Germany (n = 7). We assigned probable causes for stranding based on clinical and pathological criteria. Cause of stranding was associated in the majority of cases with pathologies in multiple organs (n = 29) compared to animals with pathologies in a single organ (n = 18). Our results show that the three most probable causes of stranding were pneumonia (n = 35), separation of calves from their mother (n = 10), and aspergillosis (n = 9). Pneumonia as a consequence of pulmonary nematode infection occurred in 19 animals. Pneumonia was significantly associated with infection with Pseudalius inflexus, Halocercus sp., and Torynurus convolutus but not with Stenurus minor infection. Half of the bacterial pneumonias (6/12) could not be associated with nematode infection. Conclusions from this study are that aspergillosis is an important probable cause for stranding, while parasitic infection is not a necessary prerequisite for bacterial pneumonia, and approximately half of the animals (29/61) probably stranded due to multiple causes. An important implication of the observed high prevalence of aspergillosis is that these harbour porpoises suffered from reduced immunocompetence.

Avian influenza overview February- August 2019

Between 16 February and 15 August 2019, five HPAI A(H5N8) outbreaks at poultry establishments in Bulgaria, two low pathogenic avian influenza (LPAI) A(H5N1) outbreaks in poultry in Denmark and one in captive birds in Germany, one LPAI A(H7N3) outbreak in poultry in Italy and one LPAI A(H7N7) outbreak in poultry in Denmark were reported in Europe. Genetic characterisation reveals that viruses from Denmark cluster with viruses previously identified in wild birds and poultry in Europe; while the Italian isolate clusters with LPAI viruses circulating in wild birds in Central Asia. No avian influenza outbreaks in wild birds were notified in Europe in the relevant period for this report. A decreased number of outbreaks in poultry and wild birds in Asia, Africa and the Middle East was reported during the time period for this report, particularly during the last three months. Furthermore, only six affected wild birds were reported in the relevant time period of this report. Currently there is no evidence of a new HPAI virus incursion from Asia into Europe. However, passive surveillance systems may not be sensitive for early detection if the prevalence or case fatality in wild birds is very low. Therefore, it is important to encourage and maintain passive surveillance in Europe encouraging a search for carcasses of wild bird species that are in the revised list of target species in order to detect any incursion of HPAI virus early and initiate warning. No human infections due to HPAI viruses - detected in wild birds and poultry outbreaks in Europe - have been reported during the last years and the risk of zoonotic transmission to the general public in Europe is considered very low.

The Canine Morbillivirus Strain Associated with An Epizootic in Caspian Seals Provides New Insights into the Evolutionary History of this Virus

Canine morbillivirus (canine distemper virus; CDV) is a worldwide distributed morbillivirus that causes sporadic cases and recurrent epizootics among an increasing number of wild, feral, and domestic animal species. We investigated the evolutionary history of CDV strains involved in the 1988 Lake Baikal (CDVPS88) and the 2000 Caspian Sea (CDVPC00) seal die-offs by recovery of full-length sequences from archived material using next-generation sequencing. Bayesian phylogenetic analyses indicated that CDVPC00 constitutes a novel strain in a separate clade (tentatively termed "Caspian") from the America-1 clade, which is comprised of older vaccine strains. The America-1/Caspian monophyletic group is positioned most basally with respect to other clades and is estimated to have separated from other CDV clades around 1832. Our results indicate that CDVPC00 recovered from the epizootic in the Caspian Sea in 2000 belongs to a previously undetected novel clade and constitutes the most ancestral wild-type CDV clade.

Zoonotic Infection With Pigeon Paramyxovirus Type 1 Linked to Fatal Pneumonia

The characteristics and risk factors of pigeon paramyxovirus type 1 (PPMV-1) infection in humans are poorly known. We performed virological, pathological, and epidemiological analyses of a Dutch case, and compared the results with those of a US case. Both infections occurred in transplant patients under immunosuppressive therapy and caused fatal respiratory failure. Both virus isolates clustered with PPMV-1, which has pigeons and doves as reservoir. Experimentally inoculated pigeons became infected and transmitted the virus to naive pigeons. Both patients were likely infected by contact with infected pigeons or doves. Given the large populations of feral pigeons with PPMV-1 infection in cities, increasing urbanization, and a higher proportion of immunocompromised individuals, the risk of severe human PPMV-1 infections may increase. We recommend testing for avian paramyxovirus type 1, including PPMV-1, in respiratory disease cases where common respiratory pathogens cannot be identified.

Seoul Virus Tropism and Pathology in Naturally Infected Feeder Rats

Seoul virus (SEOV) is a zoonotic orthohantavirus carried by black and brown rats, and can cause hemorrhagic fever with renal syndrome in humans. Human cases of SEOV virus infection have most recently been reported in the USA, United Kingdom, France and the Netherlands and were primarily associated with contact with pet rats and feeder rats. Infection of rats results in an asymptomatic but persistent infection. Little is known about the cell tropism of SEOV in its reservoir and most available data is based on experimental infection studies in which rats were inoculated via a route which does not recapitulate virus transmission in nature. Here we report the histopathological analysis of SEOV cell tropism in key target organs following natural infection of a cohort of feeder rats, comprising 19 adults and 11 juveniles. All adult rats in this study were positive for SEOV specific antibodies and viral RNA in their tissues. One juvenile rat was seropositive, but negative in the rRT-PCR. Of the 19 adult rats of which subsequently additional organs were tested, SEOV RNA was detected in all lungs, followed by kidney (79%) and liver (74%). Histopathologic changes associated with SEOV infection were primarily found in the liver, consistent with a pathological diagnosis of a mild hepatitis. In conclusion, natural SEOV infection results in mild inflammation of the liver in the absence of clinical disease.

Co-circulation of genetically distinct highly pathogenic avian influenza A clade 2.3.4.4 (H5N6) viruses in wild waterfowl and poultry in Europe and East Asia, 2017-18

Highly pathogenic avian influenza (HPAI) H5 clade 2.3.4.4 viruses were first introduced into Europe in late 2014 and re-introduced in late 2016, following detections in Asia and Russia. In contrast to the 2014–15 H5N8 wave, there was substantial local virus amplification in wild birds in Europe in 2016–17 and associated wild bird mortality, with evidence for occasional gene exchange with low pathogenic avian influenza (LPAI) viruses. Since December 2017, several European countries have again reported events or outbreaks with HPAI H5N6 reassortant viruses in both wild birds and poultry, respectively. Previous phylogenetic studies have shown that the two earliest incursions of HPAI H5N8 viruses originated in Southeast Asia and subsequently spread to Europe. In contrast, this study indicates that recent HPAI H5N6 viruses evolved from the H5N8 2016–17 viruses during 2017 by reassortment of a European HPAI H5N8 virus and wild host reservoir LPAI viruses. The genetic and phenotypic differences between these outbreaks and the continuing detections of HPAI viruses in Europe are a cause of concern for both animal and human health. The current co-circulation of potentially zoonotic HPAI and LPAI virus strains in Asia warrants the determination of drivers responsible for the global spread of Asian lineage viruses and the potential threat they pose to public health.

Streptococcus canis Are a Single Population Infecting Multiple Animal Hosts Despite the Diversity of the Universally Present M-Like Protein SCM

Streptococcus canis is an animal pathogen which occasionally causes infections in humans. The S. canis M-like protein (SCM) encoded by the scm gene, is its best characterized virulence factor but previous studies suggested it could be absent in a substantial fraction of isolates. We studied the distribution and variability of the scm gene in 188 S. canis isolates recovered from companion animals (n = 152), wild animal species (n = 20), and humans (n = 14). Multilocus sequence typing, including the first characterization of wildlife isolates, showed that the same lineages are present in all animal hosts, raising the possibility of extensive circulation between species. Whole-genome analysis revealed that emm-like genes found previously in S. canis correspond to divergent scm genes, indicating that what was previously believed to correspond to two genes is in fact the same scm locus. We designed primers allowing for the first time the successful amplification of the scm gene in all isolates. Analysis of the scm sequences identified 12 distinct types, which could be divided into two clusters: group I (76%, n = 142) and group II (24%, n = 46) sharing little sequence similarity. The predicted group I SCM showed extensive similarity with each other outside of the N-terminal hypervariable region and a conserved IgG binding domain. This domain was absent from group II SCM variants found in isolates previously thought to lack the scm gene, which also showed greater amino acid variability. Further studies are necessary to elucidate the possible host interacting partners of the group II SCM variants and their role in virulence.

Avian influenza overview November 2018 - February 2019

No human infections due to highly pathogenic avian influenza (HPAI) A(H5N8) or A(H5N6) viruses ‐ detected in wild birds and poultry outbreaks in Europe ‐ have been reported so far and the risk of zoonotic transmission to the general public in Europe is considered very low. Between 16 November 2018 and 15 February 2019, two HPAI A(H5N8) outbreaks in poultry establishments in Bulgaria, two HPAI A(H5N6) outbreaks in wild birds in Denmark and one low pathogenic avian influenza (LPAI) A(H5N3) in captive birds in the Netherlands were reported in the European Union (EU). Genetic characterisation of the HPAI A(H5N6) viruses reveals that they cluster with the A(H5N6) viruses that have been circulating in Europe since December 2017. The wild bird species involved were birds of prey and were likely infected due to hunting or scavenging infected wild waterfowl. However, HPAI virus was not detected in other wild birds during this period. Outside the EU, two HPAI outbreaks were reported in poultry during the reporting period from western Russia. Sequence information on an HPAI A(H5N6) virus found in a common gull in western Russia in October 2018 suggests that the virus clusters within clade 2.3.4.4c and is closely related to viruses that transmitted zoonotically in China. An increasing number of outbreaks in poultry and wild birds in Asia, Africa and the Middle East was observed during the time period for this report. Currently there is no evidence of a new HPAI virus incursion from Asia into Europe. However, passive surveillance systems may not be sensitive enough if the prevalence or case fatality in wild birds is very low. Nevertheless, it is important to encourage and maintain a certain level of passive surveillance in Europe testing single sick or dead wild birds and birds of prey as they may be sensitive sentinel species for the presence of HPAI virus in the environment. A well‐targeted active surveillance might complement passive surveillance to collect information on HPAI infectious status of apparently healthy wild bird populations.

Avian influenza overview August - November 2018

Between 16 August and 15 November 2018, 14 highly pathogenic avian influenza (HPAI) A(H5N8) outbreaks in poultry establishments in Bulgaria and seven HPAI A(H5N6) outbreaks, one in captive birds in Germany and six in wild birds in Denmark and the Netherlands were reported in the European Union (EU). No human infection due to HPAI A(H5N8) and A(H5N6) viruses have been reported in Europe so far. Seroconversion of people exposed during outbreaks in Russia has been reported in one study. Although the risk of zoonotic transmission to the general public in Europe is considered to be very low, appropriate personal protection measures of people exposed will reduce any potential risk. Genetic clustering of the viruses isolated from poultry in Bulgaria suggests three separate introductions in 2016 and a continuing circulation and transmission of these viruses within domestic ducks. Recent data from Bulgaria provides further indication that the sensitivity of passive surveillance of HPAI A(H5N8) in domestic ducks may be significantly compromised. Increased vigilance is needed especially during the periods of cold spells in winter when aggregations of wild birds and their movements towards areas with more favourable weather conditions may be encouraged. Two HPAI outbreaks in poultry were reported during this period from western Russia. Low numbers of HPAI outbreaks were observed in Africa and Asia, no HPAI cases were detected in wild birds in the time period relevant for this report. Although a few HPAI outbreaks were reported in Africa and Asia during the reporting period, the probability of HPAI virus introductions from non‐EU countries via wild birds particularly via the north‐eastern route from Russia is increasing, as the fall migration of wild birds from breeding and moulting sites to the wintering sites continues. Furthermore, the lower temperatures and ultraviolet radiation in winter can facilitate the environmental survival of any potential AI viruses introduced to Europe.

Reporting Avian Influenza surveillance

Avian influenza viruses infect domestic poultry and wild birds as well as humans. In poultry, depending on whether these viruses are of high pathogenicity (HPAI) or low pathogenicity (LPAI), the infection can cause different clinical signs, with HPAI causing high mortality in poultry flocks. In order to ensure early detection of avian influenza viruses, surveillance in poultry and wild birds is considered essential. In 2010, the European Commission provided some guidelines to Member States (MSs) on how this surveillance should be carried out, both in poultry and wild birds. EFSA received a mandate from the Commission to collate, validate, analyse, and summarise in an annual report the data resulting from the ongoing avian influenza surveillance programmes established in the different MSs. To deliver on this mandate, EFSA, in collaboration with the Standing Working Group on AI, initiated its activities with the drafting of a scientific report where the future vision of this collection framework was presented. Initial and later drafts of this report were shared with MS representatives in order to get feedback on the practicalities concerning the collection and submission of avian influenza surveillance data to EFSA. In the present report, the data that MSs are legally requested to submit to EFSA (‘mandatory’) and also the data that would be important to collect in order to optimise the outputs (‘desirable’) are described. A number of actions that would lead to the optimal data collection are also presented and the added value to MSs is discussed. A step‐by‐step implementation of the outlined actions is anticipated, with a description of the initial collection framework for 2019 being included in this report.

The culture of primary duck endothelial cells for the study of avian influenza

BACKGROUND

Endothelial cells play a major role in highly pathogenic avian influenza (HPAI) virus pathogenesis in gallinaceous poultry species (e.g. chicken, turkey and quail). Upon infection of gallinaceous poultry with HPAI viruses, endothelial cells throughout the body become rapidly infected, leading to systemic dissemination of the virus, disseminated intravascular coagulation, oedema and haemorrhaging. In contrast, the pathogenesis of HPAI viruses in most wild bird species (e.g. duck, goose and gull species) is not associated with endothelial tropism. Indeed, viral antigen is not found in the endothelial cells of most wild bird species following infection with HPAI viruses. This differential endothelial cell tropism in avian species is poorly understood, mainly due to the absence of appropriate cell culture systems.

RESULTS

Here, we describe the isolation and purification of primary duck endothelial cells from the aorta or bone marrow of Pekin duck embryos. Cells were differentiated in the presence of vascular endothelial growth factor and, if needed, enriched via fluorescent-activated cell sorting based on the uptake of acetylated low-density lipoprotein. The expression of von Willebrand factor, a key marker of endothelial cells, was confirmed by polymerase chain reaction. Monocultures of duck endothelial cells, either derived from the aorta or the bone marrow, were susceptible to infection with an H5N1 HPAI virus but to a much lesser extent than chicken endothelial cells.

CONCLUSIONS

The methods described herein to isolate and purify duck endothelial cells from the aorta or bone marrow could also be applied to obtain microvascular endothelial cells from other tissues and organs, such as the lung or the intestine, and represent a valuable tool to study the pathogenesis of avian viruses.

Avian influenza overview May - August 2018

Between 16 May and 15 August 2018, three highly pathogenic avian influenza (HPAI) A(H5N8) outbreaks in poultry establishments and three HPAI A(H5N6) outbreaks in wild birds were reported in Europe. Three low pathogenic avian influenza (LPAI) outbreaks were reported in three Member States. Few HPAI and LPAI bird cases have been detected in this period of the year, in accordance with the seasonal expected pattern of LPAI and HPAI. There is no evidence to date that HPAI A(H5N8) and A(H5N6) viruses circulating in Europe have caused any human infections. The risk of zoonotic transmission to the general public in Europe is considered to be very low. Several HPAI outbreaks in poultry were reported during this period from Russia. The presence of the A(H5N2) and A(H5N8) viruses in parts of Russia connected with fall migration routes of wild birds is of concern for possible introduction and spread with wild birds migrating to the EU. Although few AI outbreaks were observed in Africa, Asia and the Middle East during the reporting period, the probability of AI virus introductions from non‐EU countries via wild birds particularly via the north‐eastern route from Russia is increasing, as the fall migration of wild birds will start in the coming weeks. Further, the lower temperatures in autumn and winter may facilitate the environmental survival of avian influenza viruses potentially introduced to Europe.

Observational Study Design in Veterinary Pathology, Part 2: Methodology

Observational studies are a basis for much of our knowledge of veterinary pathology, yet considerations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offered advice on planning and carrying out an observational study. Part 2 of the series focuses on methodology. Our general recommendations are to consider using already-validated methods, published guidelines, data from primary sources, and quantitative analyses. We discuss 3 common methods in pathology research—histopathologic scoring, immunohistochemistry, and polymerase chain reaction—to illustrate principles of method validation. Some aspects of quality control include use of clear objective grading criteria, validation of key reagents, assessing sample quality, determining specificity and sensitivity, use of technical and biologic negative and positive controls, blinding of investigators, approaches to minimizing operator-dependent variation, measuring technical variation, and consistency in analysis of the different study groups. We close by discussing approaches to increasing the rigor of observational studies by corroborating results with complementary methods, using sufficiently large numbers of study subjects, consideration of the data in light of similar published studies, replicating the results in a second study population, and critical analysis of the study findings.

Observational Study Design in Veterinary Pathology, Part 1: Study Design

Observational studies are the basis for much of our knowledge of veterinary pathology and are highly relevant to the daily practice of pathology. However, recommendations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offer advice on planning and conducting an observational study with examples from the veterinary pathology literature. Investigators should recognize the importance of creativity, insight, and innovation in devising studies that solve problems and fill important gaps in knowledge. Studies should focus on specific and testable hypotheses, questions, or objectives. The methodology is developed to support these goals. We consider the merits and limitations of different types of analytic and descriptive studies, as well as of prospective vs retrospective enrollment. Investigators should define clear inclusion and exclusion criteria and select adequate numbers of study subjects, including careful selection of the most appropriate controls. Studies of causality must consider the temporal relationships between variables and the advantages of measuring incident cases rather than prevalent cases. Investigators must consider unique aspects of studies based on archived laboratory case material and take particular care to consider and mitigate the potential for selection bias and information bias. We close by discussing approaches to adding value and impact to observational studies. Part 2 of the series focuses on methodology and validation of methods.

Avian influenza overview February - May 2018

Between 16 February and 15 May 2018, three highly pathogenic avian influenza (HPAI) A(H5N6) and 11 HPAI A(H5N8) outbreaks in poultry holdings, one HPAI A(H5N6) and one HPAI A(H5N8) outbreak in captive birds, and 55 HPAI A(H5N6) wild bird events were reported in Europe. There is no evidence to date that HPAI A(H5N6) viruses circulating in Europe are associated with clades infecting humans. Fewer HPAI wild bird cases have been detected than during the same period of previous year. Most of mortality events among wild birds involved single birds and species listed in the revised list of target species for passive surveillance. Raptor species constitute 74% of the HPAI‐infected wild birds found dead. Those raptor species probably became infected by hunting or scavenging HPAI virus‐positive birds, and so raptor cases may predominate later in the course of an HPAI epidemic. Despite the important HPAI virus incursion via wild birds there have been few associated HPAI A(H5N6) outbreaks in poultry. Fifteen low pathogenic avian influenza (LPAI) outbreaks were reported in three Member States. The risk of zoonotic transmission to the general public in Europe is considered to be very low. The situation in Africa and the Middle East should be closely monitored with regards to HPAI A(H5N1) and A(H5N8). Uncontrolled spread of the virus and subsequent further genetic evolution in regions geographically connected to Europe may increase uncertainty and the risk for further dissemination of virus. Long‐distance migrating wild birds from southern Africa, e.g. the common tern (Sterna hirundo), may be included in targeted active surveillance schemes at a few priority locations in Europe in order to detect HPAI A(H5)‐infected migrating birds early. However, the risk of HPAI introduction from non‐EU countries via migratory wild birds to Europe is still considered to be much lower for wild birds crossing the southern borders than for those crossing the north‐eastern borders.

Deaths among Wild Birds during Highly Pathogenic Avian Influenza A(H5N8) Virus Outbreak, the Netherlands

During autumn-winter 2016-2017, highly pathogenic avian influenza A(H5N8) viruses caused mass die-offs among wild birds in the Netherlands. Among the ≈13,600 birds reported dead, most were tufted ducks (Aythya fuligula) and Eurasian wigeons (Anas penelope). Recurrence of avian influenza outbreaks might alter wild bird population dynamics.

Wild ducks excrete highly pathogenic avian influenza virus H5N8 (2014-2015) without clinical or pathological evidence of disease

Highly pathogenic avian influenza (HPAI) is essentially a poultry disease. Wild birds have traditionally not been involved in its spread, but the epidemiology of HPAI has changed in recent years. After its emergence in southeastern Asia in 1996, H5 HPAI virus of the Goose/Guangdong lineage has evolved into several sub-lineages, some of which have spread over thousands of kilometers via long-distance migration of wild waterbirds. In order to determine whether the virus is adapting to wild waterbirds, we experimentally inoculated the HPAI H5N8 virus clade 2.3.4.4 group A from 2014 into four key waterbird species—Eurasian wigeon (Anas penelope), common teal (Anas crecca), mallard (Anas platyrhynchos), and common pochard (Aythya ferina)—and compared virus excretion and disease severity with historical data of the HPAI H5N1 virus infection from 2005 in the same four species. Our results showed that excretion was highest in Eurasian wigeons for the 2014 virus, whereas excretion was highest in common pochards and mallards for the 2005 virus. The 2014 virus infection was subclinical in all four waterbird species, while the 2005 virus caused clinical disease and pathological changes in over 50% of the common pochards. In chickens, the 2014 virus infection caused systemic disease and high mortality, similar to the 2005 virus. In conclusion, the evidence was strongest for Eurasian wigeons as long-distance vectors for HPAI H5N8 virus from 2014. The implications of the switch in species-specific virus excretion and decreased disease severity may be that the HPAI H5 virus more easily spreads in the wild-waterbird population.