Jörn Gethmann

Monitoring of putative vectors of bluetongue virus serotype 8, Germany.

To identify the vectors of bluetongue virus (BTV) in Germany, we monitored Culicoides spp. biting midges during April 2007–May 2008. Molecular characterization of batches of midges that tested positive for BTV suggests C. obsoletus sensu stricto as a relevant vector of bluetongue disease in central Europe.

Epidemiology of Bluetongue Virus Serotype 8, Germany

In Germany, bluetongue disease had not been reported before 2006. During August 2006–August 2008, >24,000 bluetongue virus serotype 8 infections were reported, most (20,635) in 2007. In 2006 and 2007, respectively, case-fatality rates were 6.4% and 13.1% for cattle and 37.5% and 41.5% for sheep. Vaccination in 2008 decreased cases.

Efficacy of three inactivated vaccines against bluetongue virus serotype 8 in sheep.

Bluetongue has become a major animal health issue in the European Union. The member states and Switzerland have agreed on a vaccination strategy. Three different inactivated monovalent vaccines against bluetongue virus serotype 8 were selected for the compulsory vaccination program carried out in Germany in 2008. The efficacy of these vaccines was evaluated in a pilot study in sheep immunised under field conditions by clinical, virological and serological examination before and after experimental challenge infection with a BTV-8 field isolate. Antibody levels prior to challenge infection differed between the vaccinated groups, but all seroconverted animals were fully protected against clinical disease and virus replication. Only one vaccinated animal was very weakly positive in the real-time RT-PCR at day 10 after challenge infection, and one seronegative sheep in one of the vaccine groups was not protected.

Comparative safety study of three inactivated BTV-8 vaccines in sheep and cattle under field conditions

After massive epidemics of bluetongue disease in 2006 and 2007, Germany has started a compulsory vaccination program against bluetongue virus serotype 8 (BTV-8). Since the available vaccines had not yet been registered and only limited data were available on their performance, a safety study was conducted with three different inactivated monovalent vaccines under consideration for use in Germany. A total of 1007 sheep and 893 cattle were vaccinated and subsequently compared with 638 control animals (324 sheep and 314 cattle). During the study, all animals remained in good health condition. After the initial immunisation, only local swellings were observed in a small number of animals. Following revaccination, several sheep developed more distinct local reactions and a temporary rise in body temperature. Severe systemic reactions were not detected in any of the study groups. Among cattle, neither fever, nor a decrease in milk production and only temporary low-grade local reactions were observed. Overall, our results demonstrate a high level of safety of all vaccines tested.

Highly pathogenic avian influenza virus (H5N1) in frozen duck carcasses, Germany, 2007.

Article summary line: Phylogenetic and epidemiologic evidence shows incursion of HPAIV into the food chain.

BVD-2 outbreak leads to high losses in cattle farms in Western Germany

In November 2012, a dairy farmer in the district Kleve first observed a reduction in milk yield, respiratory symptoms, nasal discharge, fever, sporadic diarrhoea and sudden deaths in dairy cows and calves. In the following months, further farms were found infected with cattle showing similar clinical signs. An epidemiological investigation was carried out to identify the source of infection, the date of introduction, potential transmission pathways and to analyse the extent of the epidemic. Furthermore, laboratory analyses were conducted to characterise the causative agent. BVDV had been diagnosed in the index herd in December 2012, but due to the atypical clinical picture, the virus was not immediately recognised as the causative agent. Further laboratory analysis showed that this outbreak and subsequent infections in the area were caused by a BVD type 2c virus with a characteristic genome insertion, which seems to be associated with the occurrence of severe clinical symptoms in infected cattle. Epidemiological investigations showed that the probable date of introduction was in mid-October 2012. The high risk period was estimated as three months. A total of 21 affected farms with 5325 cattle were identified in two German Federal States. The virus was mainly transmitted by person contacts, but also by cattle trade and vehicles. The case-fatality rate was up to 60% and mortality in outbreak farms varied between 2.3 and 29.5%. The competent veterinary authorities imposed trade restrictions on affected farms. All persons who had been in contact with affected animals were advised to increase biosecurity measures (e.g. using farm-owned or disposable protective clothing). In some farms, affected animals were vaccinated against BVD to reduce clinical signs as an “emergency measure”. These measures stopped the further spread of the disease.

Disease Spread through Animal Movements: A Static and Temporal Network Analysis of Pig Trade in Germany.

Background Animal trade plays an important role for the spread of infectious diseases in livestock populations. The central question of this work is how infectious diseases can potentially spread via trade in such a livestock population. We address this question by analyzing the underlying network of animal movements. In particular, we consider pig trade in Germany, where trade actors (agricultural premises) form a complex network. Methodology The considered pig trade dataset spans several years and is analyzed with respect to its potential to spread infectious diseases. Focusing on measurements of network-topological properties, we avoid the usage of external parameters, since these properties are independent of specific pathogens. They are on the contrary of great importance for understanding any general spreading process on this particular network. We analyze the system using different network models, which include varying amounts of information: (i) static network, (ii) network as a time series of uncorrelated snapshots, (iii) temporal network, where causality is explicitly taken into account. Findings We find that a static network view captures many relevant aspects of the trade system, and premises can be classified into two clearly defined risk classes. Moreover, our results allow for an efficient allocation strategy for intervention measures using centrality measures. Data on trade volume do barely alter the results and is therefore of secondary importance. Although a static network description yields useful results, the temporal resolution of data plays an outstanding role for an in-depth understanding of spreading processes. This applies in particular for an accurate calculation of the maximum outbreak size.

Direct costs of bovine spongiform encephalopathy control measures in Germany.

On 26 November 2000, the first autochthonous case of bovine spongiform encephalopathy (BSE) was detected in Germany. Since then, a total of 413 BSE cases have been confirmed, resulting in the culling and destruction of 17 313 heads of cattle. In view of the possible risks for human and animal health, Germany has adopted EU regulations along with some additional requirements concerning active surveillance and response measures after detecting a BSE‐positive animal. In this study, we used a stochastic model to estimate the costs incurred by the ensuing legislative amendments responding to BSE between November 2000 and December 2010. The total costs were estimated to range between 1847 and 2094 million Euros. They peaked in 2001 (about 394 million Euros) and declined since. About 54% of the costs (approximately 1000 million Euros) were incurred by the extension of the feed ban for animal protein to all farmed livestock. Active surveillance accounted for 21% (405 million Euros), the incineration of animal protein for 13% (249 million Euros) and the removal of specified risk material for 11% (225 million Euros). Only 1% of the costs was related to response measures after detecting a BSE‐positive animal, including indemnity payments for culled cattle and confiscated carcasses at the slaughterhouse.

Six Years (2011–2016) of Mandatory Nationwide Bovine Viral Diarrhea Control in Germany—A Success Story

Bovine viral diarrhea (BVD) is one of the most important infectious diseases in cattle, causing major economic losses worldwide. Therefore, control programs have been implemented in several countries. In Germany, an obligatory nationwide eradication program has been in force since 2011. Its centerpiece is the detection of animals persistently infected (PI) with BVD virus, primarily based on the testing of ear tissue samples of all newborn calves for viral genome or antigen, and their removal from the cattle population. More than 48,000 PI animals have so far been detected and removed. Between the onset of the program and the end of 2016, the prevalence of these animals among all newborn calves decreased considerably, from 0.5% to less than 0.03%. The number of cattle holdings with PI animals likewise decreased from 3.44% in 2011 to only 0.16% in 2016. Since a large number of naïve, fully susceptible animals are now confronted with BVD virus, which is still present in the German cattle population, the challenge of the coming years will be the identification of remaining PI animals as quickly and efficiently as possible, and the efficient protection of BVD-free farms from reinfection.

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.