A. de la Torre

Assessing the risk of African swine fever introduction into the European Union by wild boar.

The presence of African swine fever (ASF) in the Caucasus region and Russian Federation has increased concerns that wild boars may introduce the ASF virus into the European Union (EU). This study describes a semi-quantitative approach for evaluating the risk of ASF introduction into the EU by wild boar movements based on the following risk estimators: the susceptible population of (1) wild boars and (2) domestic pigs in the country of origin; the outbreak density in (3) wild boars and (4) domestic pigs in the countries of origin, the (5) suitable habitat for wild boars along the EU border; and the distance between the EU border and the nearest ASF outbreak in (6) wild boars or (7) domestic pigs. Sensitivity analysis was performed to identify the most influential risk estimators. The highest risk was found to be concentrated in Finland, Romania, Latvia and Poland, and wild boar habitat and outbreak density were the two most important risk estimators. Animal health authorities in at-risk countries should be aware of these risk estimators and should communicate closely with wild boar hunters and pig farmers to rapidly detect and control ASF.

Quantitative risk assessment of foot-and-mouth disease introduction into Spain via importation of live animals

Spain has been a foot-and-mouth disease (FMD)-free country since 1986. However, the FMD epidemics that recently affected several European Union (EU) member countries demonstrated that the continent is still at high risk for FMD virus (FMDV) introduction, and that the potential consequences of those epidemics are socially and financially devastating. This paper presents a quantitative assessment of the risk of FMDV introduction into Spain. Results suggest that provinces in north-eastern Spain are at higher risk for FMDV introduction, that an FMD epidemic in Spain is more likely to occur via the import of pigs than through the import of cattle, sheep, or goats, and that a sixfold increase in the proportion of premises that quarantine pigs prior to their introduction into the operation will reduce the probability of FMDV introduction via import of live pigs into Spain by 50%. Allocation of resources towards surveillance activities in regions and types of operations at high risk for FMDV introduction and into the development of policies to promote quarantine and other biosecurity activities in susceptible operations will decrease the probability of FMD introduction into the country and will strengthen the chances of success of the Spanish FMD prevention program.

First Case of Highly Pathogenic Avian Influenza in Poultry in Spain

In October 2009, highly pathogenic avian influenza virus (HPAIV) was isolated for the first time in poultry in Spain. Sequencing analysis revealed that it was an H7N7 HPAIV. The progenitors of H7 HPAIV strains involved in recent European poultry outbreaks were simultaneously circulating in wild birds. The infected Spanish farm is located close to a reservoir abundant in wild birds. Epidemiological investigation found no links to other poultry holdings and those located in the control area were negative for AIV. Previous spatial risk analyses had identified the area where the infected holding is located to beat high relative risk for the introduction and presence of H5N1 HPAIV by wild birds. We suggest a risk-based surveillance scheme that targets smaller geographical units but maintains the number of wild birds being sampled, as early detection of potentially pathogenic AIV is crucial in preventing spread to poultry.

Identifying areas for infectious animal disease surveillance in the absence of population data: highly pathogenic avian influenza in wild bird populations of Europe.

A large number (n=591) of H5N1 highly pathogenic avian influenza virus (HPAIV) outbreaks have been reported in wild birds of Europe from October 2005 through January 2009. Consequently, prevention and control strategies have been implemented in response to the outbreaks and considerable discussion has taken place regarding the need for implementing surveillance programs in high-risk areas with the objective of early detecting and preventing HPAIV epidemics. However countries ability to define the temporal and spatial extension of the high risk areas has been impaired by the lack of information on the distribution of susceptible wild bird populations in the region. Here, a technique for the detection of time-space disease clustering that does not require information on the distribution of susceptible populations and that has been referred to as the time-space permutation model of the scan statistic was used to identify areas and times of the year in which epidemics of H5N1 HPAIV were most likely to occur in wild bird populations of Europe from October, 2005, through December, 2008. The scan statistic was parameterized considering pre-existing knowledge on the epidemiological and ecological characteristics of the disease in the region. Robustness of the results was assessed using a generalized linear regression model to compare the outcomes of 36 alternative parameterizations of the scan statistic. Ten significant time-space clusters of H5N1 HPAI outbreaks were detected in six European countries. Results were sensitive (P<0.05) to the definition of the maximum spatial size defined for the clusters. Results presented here will help to identify high risk areas for HPAIV surveillance in the European Union. Assumptions, results, and implications of the analytical model are extensively presented and discussed in order to facilitate the use of this approach for the identification of high risk areas for infectious animal disease surveillance in the absence of population data.

Vector‐Borne Pathogen Spread Through Ticks on Migratory Birds: A Probabilistic Spatial Risk Model for South‐Western Europe

Tick-borne pathogens can spread easily through the movements of infested birds. An important example is viruses that pose a threat to humans and that are carried in Hyalomma ticks that move from Africa into south-western Europe. This study evaluates the probability of arrival of migrating birds from Africa into Spain and the environmental suitability of different regions of Spain for the survival of tick stages introduced by these birds. This evaluation produced a spatial risk index measuring the probability that foreign tick populations will survive in the target area. Periods of highest risk were observed for large areas of Spain, from the second fortnight of April to the second fortnight of May. Although birds may arrive as early as January and massive migrations may take place in March, the environmental suitability for Hyalomma marginatum ticks is low in these periods and high mortality of the spread stages (nymphs) is expected. This study introduces new methods of objective analysis based on spatial and process-driven models for both ticks and hosts and critically evaluates the usefulness of spatial spreading methods for assessing the risk of tick-borne pathogens.

Evaluating surveillance in wild birds by the application of risk assessment of avian influenza introduction into Spain

Early detection of highly pathogenic avian influenza (HPAI) in its natural reservoirs is a prerequisite for preventing disease spread to humans. The risk of introduction of H5N1 HPAI was assessed in order to design a risk-based surveillance system in Spain. Areas at highest risk for H5N1 HPAI followed a northeast-southwest direction, with two significant clusters located in the north and the southwest of the country. Most (83%) of the veterinary units (VUs) obtained fewer samples than would have been expected if samples had been collected using a risk-based design. In October 2009, a HPAI outbreak was reported for the first time in a Spanish layer farm located in a VU at high risk for HPAI, but no samples were collected. This risk-based surveillance approach will increase the cost-effectiveness of HPAI surveillance in Spain and can be easily extended to and adopted by other countries and regions throughout the world.

Association between number of wild birds sampled for identification of H5N1 avian influenza virus and incidence of the disease in the European Union

Fourteen European Union (EU) countries have been affected by highly pathogenic avian influenza (HPAI) of the subtype H5N1 since 2005. Many of the H5N1 HPAI cases have been identified in wild bird populations from aquatic habitats. The objective of this contribution was to assess the association between the H5N1 HPAI incidence, estimated by a co-kriging approach, and the number of wild birds sampled for H5N1 HPAI surveillance in EU countries. The probability that a sample for H5N1 HPAI surveillance collected in the EU was obtained from a given country was associated (P<0.01) with the probability that a H5N1 HPAI case reported in the EU was located in the same country. The relation between probability of sampling and probability of infection in the Netherlands and in Spain was significantly higher (P<0.01) than that estimated in other EU countries, suggesting that political or social factors may have selectively influenced the number of samples for H5N1 HPAI surveillance collected in those two countries. The approach presented here will be useful for post hoc comparison of the relation between probability or risk for disease and the intensity of surveillance activities among administrative divisions of a region.

Reproductive ratio for the local spread of highly pathogenic avian influenza in wild bird populations of Europe, 2005–2008

Highly pathogenic avian influenza (HPAI) has devastating consequences for the poultry industry of affected countries. Control of HPAI has been impaired by the role of wildlife species that act as disease reservoirs and as a potential source of infection for domestic populations. The reproductive ratio (R₀) of HPAI was quantified in nine clusters of outbreaks detected in wild birds in Europe (2005-2008) for which population data were not available. The median value of R₀ was similar (1·1-3·4) for the nine clusters and it was about tenfold smaller than the value estimated for poultry in The Netherlands in 2003. Results presented here will be useful to parameterize models for spread of HPAI in wild birds and to design effective prevention programmes for the European poultry sector. The method is suitable to estimate R₀ in the absence of population data, which is a condition typically observed for many wildlife and certain domestic species and systems.

Risk Assessment Applied to Spain's Prevention Strategy Against Highly Pathogenic Avian Influenza Virus H5N1

Abstract Notifiable avian influenza (NAI) had never been reported in Spain, until July 2006 when a dead Great Crested Grebe (Podiceps cristatus) was found positive to the highly pathogenic H5N1 subtype as part of the active wild bird surveillance plan. The current program of the Spanish Ministry of Agriculture, Fisheries, and Food (MAPA)s strategic preventive plan against NAI is divided in the following parts: identification of risk areas and risk wild bird species, increased biosecurity measures, early detection of infection with surveillance intensification and development of rapid diagnostic tests, and other policies, which include continuing education and training to ensure early detection of the disease. In 2003 an active surveillance plan was introduced for domestic fowl; the plan was extended to wild birds in 2004. A total of 18,780 samples in poultry and 3687 samples in wild birds had been analyzed through December 2005 to detect the presence and spread of avian influenza subtypes H5 and H7. In the present work we suggest some contributions to be implemented in MAPAs action plan: 1) the identification of risks because of migratory birds, within the risk assessment of the introduction of NAI virus in Spain and 2) an interactive digital simulator of the disease developed for continuing education and training.

Detection of Bovine Viral Diarrhoea Virus 2 as the Cause of Abortion Outbreaks on Commercial Sheep Flocks

&NA; Outbreaks of abortions and lambs born with nervous clinical signs and/or congenital malformations affected different sheep farms in Spain. Initial diagnosis of ‘border disease‐like’ was established, based on clinical signs, serology and/or RNA detection by a pan‐pestivirus RT‐PCR. However, further investigation using immunohistochemical and molecular techniques identified BVDV‐2b as the aetiological agent.