Klaas Dietze

Outbreaks among Wild Birds and Domestic Poultry Caused by Reassorted Influenza A(H5N8) Clade 2.3.4.4 Viruses, Germany, 2016

In November 2016, an influenza A(H5N8) outbreak caused deaths of wild birds and domestic poultry in Germany. Clade 2.3.4.4 virus was closely related to viruses detected at the Russia–Mongolia border in 2016 but had new polymerase acidic and nucleoprotein segments. These new strains may be more efficiently transmitted to and shed by birds.

Highly Pathogenic Avian Influenza H5N8 in Germany: Outbreak Investigations.

Epidemiological outbreak investigations were conducted in highly pathogenic avian influenza virus of the subtype H5N8 (HPAIV H5N8)-affected poultry holdings and a zoo to identify potential routes of entry of the pathogen via water, feedstuffs, animals, people, bedding material, other fomites (equipment, vehicles etc.) and the presence of wild birds near affected holdings. Indirect introduction of HPAIV H5N8 via material contaminated by infected wild bird seems the most reasonable explanation for the observed outbreak series in three commercial holdings in Mecklenburg-Western Pomerania and Lower Saxony, while direct contact to infected wild birds may have led to outbreaks in a zoo in Rostock and in two small free-range holdings in Anklam, Mecklenburg-Western Pomerania.

Oral vaccination of backyard pigs against classical swine fever.

Vaccination represents a key pillar of most classical swine fever (CSF) control programmes. In backyard production systems the systematic implementation of parenteral vaccination proves to be difficult and alternative delivery mechanisms might be needed. In this study the use of oral vaccination against CSF in backyard pigs was tested under field conditions. The main objective was to assess uptake efficacy and immune response after oral vaccination of backyard pigs with bait vaccine currently used in the European Union for CSF control in wild boar (RIEMSER(®) Schweinepestoralvakzine). In total 85 backyard pigs belonging to 16 holdings were vaccinated orally by distributing four baits per pig, given on two consecutive days. The baits were distributed on pen floors. 73% of the pigs older than 12 weeks (n=41) had protective antibody titres 28 days after oral vaccination. The seroconversion rate in young piglets (n=44, younger than 12 weeks) was 64%. Based on the results obtained we concluded that in an endemic situation where usual control measures (stamping out, zoning with restrictive measures, parenteral vaccination, etc.) may prove to be insufficient, a systematic vaccination based on the use of oral vaccine can be an appropriate tool for an improved CSF control in backyard production systems.

Rope-based oral fluid sampling for early detection of classical swine fever in domestic pigs at group level

BackgroundNon-invasive sampling techniques based on the analysis of oral fluid specimen have gained substantial importance in the field of swine herd management. Methodological advances have a focus on endemic viral diseases in commercial pig production. More recently, these approaches have been adapted to non-invasive sampling of wild boar for transboundary animal disease detection for which these effective population level sampling methods have not been available. In this study, a rope-in-a-bait based oral fluid sampling technique was tested to detect classical swine fever virus nucleic acid shedding from experimentally infected domestic pigs.ResultsSeparated in two groups treated identically, the course of the infection was slightly differing in terms of onset of the clinical signs and levels of viral ribonucleic acid detection in the blood and oral fluid. The technique was capable of detecting classical swine fever virus nucleic acid as of day 7 post infection coinciding with the first detection in conventional oropharyngeal swab samples from some individual animals. Except for day 7 post infection in the “slower onset group”, the chances of classical swine fever virus nucleic acid detection in ropes were identical or higher as compared to the individual sampling.ConclusionsWith the provided evidence, non-invasive oral fluid sampling at group level can be considered as additional cost-effective detection tool in classical swine fever prevention and control strategies. The proposed methodology is of particular use in production systems with reduced access to veterinary services such as backyard or scavenging pig production where it can be integrated in feeding or baiting practices.

Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4b in Germany in 2016/2017

Here, we report on the occurrence of highly pathogenic avian influenza (HPAI) H5Nx clade 2.3.4.4b in Germany. Between November 8, 2016, and September 30, 2017, more than 1,150 cases of HPAI H5Nx clade 2.3.4.4b in wild birds and 107 outbreaks in birds kept in captivity (92 poultry holdings and 15 zoos/animal parks) were reported in Germany. This HPAI epidemic is the most severe recorded in Germany so far. The viruses were apparently introduced by migratory birds, sparking an epidemic among wild birds across Germany with occasional incursions into poultry holdings, zoos and animal parks, which were usually rapidly detected and controlled by stamping out. HPAI viruses (mainly subtype H5N8, in a few cases also H5N5) were found in dead wild birds of at least 53 species. The affected wild birds were water birds (including gulls, storks, herons, and cormorants) and scavenging birds (birds of prey, owls, and crows). In a number of cases, substantial gaps in farm biosecurity may have eased virus entry into the holdings. In a second wave of the epidemic starting from February 2017, there was epidemiological and molecular evidence for virus transmission of the infections between commercial turkey holdings in an area of high poultry density, which caused approximately 25% of the total number of outbreaks in poultry. Biosecurity measures in poultry holdings should be adapted. This includes, inter alia, wearing of stable-specific protective clothing and footwear, cleaning, and disinfection of equipment that has been in contact with birds and prevention of contacts between poultry and wild water birds.

Prospects of improved classical swine fever control in backyard pigs through oral vaccination

Success in controlling classical swine fever (CSF) in regions with high proportions of pigs kept in small scale and low-biosecurity production systems, often referred to as backyard production, tends to be hampered by the lack of control strategies properly addressing the peculiarities of this epidemiologically important subpopulation. Under many circumstances the commonly practiced parenteral immunisation using live attenuated C-strain vaccine shows limitations concerning outreach of services and overall vaccination coverage in the backyard pig population. It is therefore proposed to stronger consider oral vaccine baits, as used for CSF control in wild boar, to complement the set of tools for CSF control in domestic pigs. First field results confirm the feasibility of its practical implementation. Next to the increased flexibility in the delivery to the end user, this non-invasive method comes along with the advantage of reducing the need for direct animal contact and biosecurity-relevant interventions that might cause the spread of diseases through vaccination campaigns entailing external personnel entering farm premises. In combination with epidemiological methods suitable for this production sector like e.g. participatory epidemiology, adapted CSF control strategies can better support the needs of small scale farmers and ultimately contribute to household food security for a large number of stakeholders that will have backyard pig production as a reality for decades to come.

Suitability of group-level oral fluid sampling in ruminant populations for lumpy skin disease virus detection

The geographic expansion of Lumpy skin disease (LSD) from the near East into the European Union highlighted again the need for appropriate disease detection tools applicable to animal host populations where access to individual animals is difficult. This is of particular importance considering that the clinical manifestation of LSD is often mild making early disease detection challenging under the above-mentioned conditions. Building on positive experiences of group-level oral fluid sampling for pathogen detection as it is known to work for swine herds and wild boar, the concept was transferred to ruminants. Two groups of six cattle were infected experimentally with Lumpy skin disease virus (LSDV) under controlled conditions. Blood as well as oropharyngeal and nasal swab samples were collected at regular intervals. Group samples were obtained by placing cotton gauze around a salt lick block provided commonly as dietary supplement. Pieces of the gauze with visible signs of manipulation were tested in parallel to samples obtained from individual animals. Genome load analysis by qPCR technology revealed LSDV detection window starting from day 2 post infection until day 28 post infection, the end of the animal trial. At the individual level, detection periods varied between animals and type of sample and included intermitted detection. The accumulative character of the alternative sampling method makes it suitable to detect LSDV DNA at group-level even at times of the infection where a selective sampling of individuals from a group - as normally done in LSD surveillance - would have most likely failed in the detection.