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In this project it is evaluated how the use of C-strain vaccine instead of E2-subunit vaccine will affect the effectiveness of controlling Classical Swine Fever (CSF). To this end a CSF transmission model was developed that describes virus transmission on three different levels: between animals, between pens and between herds. The results of transmission and vaccination experiments as well as the data from the 1997/1998 CSF epidemic in The Netherlands serve to parameterize the model. With the model hypothetical epidemics are simulated under different scenarios.

Bayesian networks are typically designed in collaboration with a single domain expert from a single institute. Since a network is often intended for wider use, its engineering involves verifying whether it appropriately reflects expert knowledge from other institutes. Upon engineering a network intended for use across Europe, we compared the original probability assessments obtained from our Dutch expert with assessments from 38 experts in six countries. While we found large variances among the assessments per probability, very high consistency was found for the qualitative properties embedded in the series of assessments per assessor. The apparent robustness of these properties suggests the importance of enforcing them in a Bayesian network under construction.

This publication is based on a talk which was held in the course of the spring symposium „Impfen statt Keulen“ of the Akademie für Tiergesundheit (AfT) 2011 in Wiesbaden-Naurod. Experience with recent large-scale epidemics of Classical Swine Fever and Avian Influenza – among others in the Netherlands – have teached us several lessons that should prepare us better for future outbreaks. Among others, improving early detection of outbreaks – by using syndrome surveillance systems – is a key factor, in which farmers and veterinary practitioners have an imminent role. A major step in this respect is facilitation of the use of exclusion diagnostics without closing down the farm in clinical situations with non-specific clinical signs observed in sick animals. The hesitance of farmers and veterinary practitioners to report a suspect clinical situation on a livestock farm and how to facilitate that process is another major issue. Furthermore, the importance of communication between the field and the laboratory with respect to post mortem examination will be highlighted, and the need for outbreak simulation exercises with neighbouring countries in order to be better prepared, will be discussed.

In 2009 a new influenza A/H1N1 virus strain ("pandemic (H1N1) 2009", H1N1v) emerged that rapidly spread around the world. The virus is suspected to have originated in swine through reassortment and to have subsequently crossed the species-barrier towards humans. Several cases of reintroduction into pigs have since been reported, which could possibly create a reservoir for human exposure or ultimately become endemic in the pig population with similar clinical disease problems as current swine influenza strains. A soluble trimer of hemagglutinin (HA), derived from the H1N1v, was used as a vaccine in pigs to investigate the extent to which this vaccine would be able to protect pigs against infection with the H1N1v influenza strain, especially with respect to reducing virus replication and excretion. In a group of unvaccinated control pigs, no clinical symptoms were observed, but (histo)pathological changes consistent with an influenza infection were found on days 1 and 3 after inoculation. Live virus was isolated from the upper and lower respiratory tract, with titres up to 10(6) TCID(50) per gram of tissue. Furthermore, live virus was detected in brain samples. Control pigs were shedding live virus for up to 6 days after infection, with titres of up to 10(5) TCID(50) per nasal or oropharyngeal swab. The soluble H1N1v HA trimer diminished virus replication and excretion after a double vaccination and subsequent challenge. Live virus could not be detected in any of the samples taken from the vaccinated pigs. Vaccines based on soluble HA trimers provide an attractive alternative to the current inactivated vaccines.

Several routes contribute to the spread of classical swine fever (CSF) during outbreaks of this disease. However, for many infected herds in recent epidemics, no route of virus introduction could be indentified. To obtain more insight into the relative importance of secretions and excretions in transmission of CSF virus, a model was developed. This model quantified the daily transmission probabilities from one infectious pig to one susceptible pig, using quantitative data on: (a) virus excretion by infected pigs, (b) survival of virus in the environment and (c) virus dose needed to infect susceptible pigs. Furthermore, the model predicted the relative contribution of secretions and excretions to this daily probability of infection of a susceptible pig. Three virus strains that differed in virulence were evaluated with the model: the highly virulent strain Brescia, the moderately virulent strain Paderborn and the low virulent strain Zoelen. Results suggest that it is highly probable that susceptible pigs in contact with Brescia or Paderborn infected pigs will be infected. For a pig in contact with a Zoelen infected pig, infection is less likely. When contact with blood is excluded, the predicted overall probability of infection was only 0.08 over the entire infectious period. The three strains differed in the relative contribution of secretions and excretions to transmission, although blood had a high probability of causing infection of a susceptible pig when in contact with a pig infected with any strain. This supports the statement that during outbreaks, control measures should ideally be based on the characteristics of the specific virus strain involved, which implies the development of strain-specific measures.

In april 2009 werden in Californië (VS) twee kinderen ziek met wat later een nieuw type griepvirus (influenza) zou blijken te zijn. Influenzaachtige verschijnselen waren in de maand daarvoor al opvallend veel waargenomen in Mexico. Deze bleken te zijn veroorzaakt door hetzelfde type griepvirus. Al snel werd deze influenzavariant bekend onder de naam Mexicaanse griep

Influenza virus infections in swine were first noticed in the US in 1918, during the human pandemic of the Spanish flu. In Europe, seroprevalences for the three most common swine influenza strains at the moment, H1N1, H3N2 and H1N2, range from 20-80% in finishing pigs at the end of the finishing period and in sows. However, little is known about the population dynamics of influenza virus within herds, or between herds. By investigating 53 outbreaks of acute respiratory disease over a period of four years, it was established that influenza virus infections are responsible for more than 50% of the acute respiratory disease outbreaks in swine. Virus circulation in weaned piglets was found to be very common, suggesting that weaned piglets may act as a reservoir for influenza virus in a herd. Virus infections at that time interfere with the presence of maternal antibodies, resulting in no noticeable clinical symptoms, but also in a lesser immunity than infections in fully susceptible pigs. The occurrence of influenza virus infections in finishing pigs was quite different in farrow-to finish herds when compared to finishing herds. For all subtypes, influenza virus infections in farrow-to-finish herds occurred mainly at a young age, up to and including the first half of the finishing period. In finishing herds on the other hand, the influenza virus infections mainly occurred in the second half of the finishing period. These differences may have implications for the choice of intervention measures, whether this is intervention through vaccination, or intervention through zoosanitary measures. Vaccines, while potentially highly efficacious, have the disadvantage that they are very specific for one infectious agent, or even one subtype of an infectious agent. The big advantage of zoosanitary measures compared to vaccination is that multiple infectious agents can be addressed at the same time with the same or similar measures. Measures with respect to air filtration and increased hygiene were therefore evaluated. These measures significantly reduced the number of influenza virus infections during the finishing period and therefore most likely also the magnitude of acute respiratory disease. These measures are unlikely to be cost-beneficial when they are only applied for influenza virus infections, but the application of such measures in a broader context may offer some prospects

Het is dit jaar geleden dat in Nederland het geval van klassieke varkenspest werd gedetecteerd. Het was het laatste geval in een epidemie die ruim een jaar had geduurd. Op dat moment waren we 429 besmette bedrijven verder, waren 12 miljoen varkens vernietigd en was de schade opgelopen tot meer dan 2 miljard euro. Om nog maar te zwijgen over de emotionele en psychotische schade bij vele betrokkenen. Sindsdien zit de angst voor een nieuwe uitbraak er goed in en zijn er veel maatregelen genomen om een herhaling te voorkomen. Een van die maatregelen is het aanpassen van het beleidsdraaiboek en het daarin opnemen van de optie om tijdens een volgende uitbraak eventueel te gaan vaccineren met een markergen. Het CV1 heeft veel onderzoek gedaan naar effectiviteit en veiligheid van een vaccinatiestrategie met markervaccins. Onder andere werd onderzocht wat de kans is dat gevaccineerde dieren na infectie een chronische infectie ontwikkelen en vervolgens langdurig infectieus zijn

Een attenderingswaarschuwing om bij een verdachte situatie niet alleen rekening te houden met de klassieke varkenspest, maar ook met de Afrikaanse varkenspest

Rapid and accurate diagnosis is of the utmost importance in the control of epizootic diseases such as classical swine fever (CSF), and efficacious vaccination can be used as a supporting tool. While most of the recently developed CSF vaccines and diagnostic kits are mostly validated according to World Organisation for Animal Health (OIE) standards, not all of the well-established traditional vaccines and diagnostic tests were subject to these validation procedures and requirements. In this report, data were compiled on performance and validation of CSF diagnostic tests and vaccines. In addition, current strategies for differentiating infected from vaccinated animals are reviewed, as is information on the control of CSF in wildlife. Evaluation data on diagnostic tests were kindly provided by National Reference Laboratories for CSF in various European countries

APF-stal kan binnendringen infecties tegengaan