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. As a case study, we consider pig trade in Germany, where trade actors (agricultural premises) form a complex network. The central question is how infectious diseases can potentially spread within the system of trade contacts. We address this question by analyzing the underlying network of animal movements. Methodology/Findings: 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: Our approach provides a general framework for a topological-temporal characterization of livestock trade networks. 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 does 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.Comment: main text 33 pages, 17 figures, supporting information 7 pages, 7 figure

An epidemiological and economic simulation model to evaluate strategies for the control of bovine virus diarrhea in Germany

Models can be used to plan, evaluate, and improve programs for animal disease control. In Germany, a nationwide compulsory program to eradicate Bovine viral diarrhea (BVD) is in force since January 2011. As it is associated with substantial expenditures, the program is currently under revision. To provide the basis for a science-based decision on the future course of BVD control in Germany, we evaluated 13 scenarios (sc1-13) with respect to the chance of reaching freedom from disease and their economic implications for a period of 20 years (2011–2030). To simulate the impact of different control strategies on disease dynamics, a disease spread model was developed. To estimate the effects of a transient infection (TI) on animal level, a gross margin analysis was performed. To assess the value of cattle that died prematurely, a valuation model was used. Finally, an economic model was developed to perform a cost-benefit analysis and to compare each control scenario with a baseline setting with no BVD control. Costs comprised the expenditures for diagnostics, vaccination, preventive culling, and trade restrictions. Benefits were animal and production losses avoided by having control measures in place. The results show that reducing the PI prevalence on animal level to 0% is only feasible in scenarios that combine antigen or antibody testing with compulsory vaccination. All other scenarios, i.e., those based exclusively on a “test and cull” approach, including the current control program, will, according to the model, not achieve freedom of BVD by 2030. On the other hand, none of the scenarios that may lead to complete BVD eradication is economically attractive [benefit-cost ratio (BCR) between 0.64 and 0.94]. The average direct costs of BVD in Germany are estimated at 113 million Euros per year (34–402 million Euros), corresponding to 28.3 million Euros per million animals. Only the concepts of the former and the current national BVD control program (“ear tag testing and culling”) may reduce the BVD prevalence to 0.01% with an acceptable BCR (net present value of 222 and 238 million Euros, respectively, with a BCR of 1.22 and 1.24)

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

Bakterielle Zoonosen mit Bedeutung für den öffentlichen Gesundheitsschutz in Deutschland – Vorkommen, Verbreitung und Übertragungswege

Bakterielle zoonotische Erreger sind häufig Auslöser von Erkrankungen mit teilweise schweren Verläufen. Sie sind wechselseitig zwischen Tieren (sowohl Wild- als auch Haustieren) und Menschen übertragbar. Die Transmissionswege sind sehr variabel, so kann die Übertragung u. a. durch orale Aufnahme über Lebensmittel, respiratorische Aufnahme über Tröpfchen und Aerosole sowie über Vektoren wie Zeckenstiche oder Nagerkontakte stattfinden. In diesem Zusammenhang sind auch das Auftreten und die Verbreitung von antibiotikaresistenten bakteriellen Erregern von zunehmender Bedeutung für den öffentlichen Gesundheitsschutz. Die Ausbreitung zoonotischer Erreger wird aktuell durch zahlreiche Faktoren verstärkt. Dazu gehören die Zunahme des internationalen Warenverkehrs, die Einengung der Lebensräume von Tieren und der dadurch zunehmend engere Kontakt zwischen Menschen und Wildtieren. Aber auch eine veränderte Tierhaltung in der Landwirtschaft und Klimaveränderungen können zur Ausbreitung beitragen. Der öffentliche Gesundheitsschutz und die Erforschung von Zoonosen sind deshalb von besonderer krankheitspräventiver, aber auch gesellschaftlicher, politischer und wirtschaftlicher Bedeutung. Ziel dieses Übersichtsartikels ist es, anhand von Beispielen die Spannbreite von Infektionskrankheiten darzustellen, die durch bakterielle zoonotische Erreger ausgelöst werden. Die unterschiedlichen Transmissionswege, epidemischen Potenziale und epidemiologischen Maßzahlen der beispielhaft gewählten Krankheiten sind Herausforderungen für den öffentlichen Gesundheitsdienst, den Tiergesundheitsdienst und die Lebensmittelüberwachung, deren Aufgabe es ist, die Bevölkerung vor diesen Infektionskrankheiten zu schützen.Bacterial zoonotic pathogens are often the cause of diseases, sometimes with severe outcomes. They are mutually transferable between animals (both wild and domestic) and humans. The transmission paths are very variable and include oral intake via food, respiratory infection via droplets and aerosols, or infections via vectors such as tick bites or rodent contact. Furthermore, the emergence and spread of antibiotic-resistant bacterial pathogens is of paramount public health concern. The likelihood of further spread is influenced by various factors. These include the increase in international trade, the endangerment of animal habitats, and the increasingly closer contact between humans and wild animals. Additionally, changes in livestock and climate change may also contribute. Therefore, research into zoonoses serves to protect human and animal health and is of particular social, political, and economic importance. The aim of this review article is to present the range of infectious diseases caused by bacterial zoonotic pathogens in order to provide a better understanding of the important work in public health services, animal health services, and food safety control. The different transmission routes, epidemic potentials, and epidemiological measures of the exemplary selected diseases show the challenges for the public health system to monitor and control the spread of these bacterial pathogens in order to protect the population from disease.Peer Reviewe