Progress of the Aujeszky's disease virus eradication programme in Brittany (France)

Brittany is the main pig production area in France. About 14 million fatteners are produced per year in this province. There are 9200 farms holding about $690\,000$ sows. Farrow-to-finish herds are prevalent representing half of the farms and 70% of the production. More than 4 million piglets are transported per year. An eradication program for Aujeszky's disease is currently in action. The key points of this program are: (1) yearly general serological screening, (2) quarterly blood testing of nucleus and multipliers herds, (3) compulsory vaccination, (4) special authorisation needed to move piglets out of non-AD free farms given by veterinary services. The yearly general serological screening for Aujeszky's disease has been compulsory since 1994. The herds were sampled from October 1st to May 31st. Fifteen sows were bled in each breeding stock and fifteen fatteners in each fattening stock. Vaccines used were marker vaccines and serological analysis were GE ELISA. A herd was declared positive when at least one of the sera was positive. For the Farrowing-to-Finish farms (FAFI), serological status of the breeding unit was considered to be independent of the fattening unit. A database of all the herds was available. For each herd, its production type (Farrowing-to-Feeder (FAFE), Farrowing-to-Finish (FAFI) and Feeder-to-Finish (FEFI), size and location were known. The seroprevalence of breeding stocks of FAFE and FAFI herds was respectively 23.2% and 28.1% in 1994/1995, 11.3% and 14.4% in 1995/1996, 4.8% and 8.3% in 1996/1997, 2.7% and 5.3% in 1997/1998. The seroprevalence of fattening stocks of FAFI and FEFI herds was respectively 13.2% and 17.2% in 1994/1995, 5.4% and 6.7% in 1995/1996, 3.4% and 5.3% in 1996/1997, 2.6% and 2.6% in 1997/1998. Despite some local resurgence, seroprevalence has decreased every year since 1994, whatever the production type. However, the evolution seems to be asymptotic. The decrease of infection rates which was considerable the two first years, has been less important since then. Moreover the seroprevalence of breeding stocks of FAFI, which was close to that of FAFE in 1994/95, was twice more important in 1997/98. This figure gives evidence of some difficulties to eradicate Aujeszky's disease in some FAFI herds, where fatteners are very close to sows. In the same way, FEFI fattening stocks were more contaminated than FAFI stocks in 1994/95. In 1997/1998, infection rates of both production types were equivalent. This figure is certainly related to the control of animal movements which tends to decrease the risk of FEFI herds being purchased with infected piglets. The eradication plan now has to focus on herds remaining infected despite vaccination. A "test and removal" program will begin at the end of 1999. Vaccination will have to be continued until the last positive animal of the region is slaughtered

Risk factors of new Aujeszky's disease virus infection in swine herds in Brittany (France)

Brittany is the main pig production area in France. About 14 million fatteners are produced every year in this province. There are about 9 300 farms holding 690 000 sows. Vaccination against Aujeszky's disease is compulsory, and all vaccines which are used are marker vaccines. Since 1994, a yearly general serological screening has been performed. All herds are bled at least once a year. Fifteen sows are bled in each breeding stocks and 15 fatteners in each fattening stock. All serological analyses are GE ELISA. The seroprevalence of herds has been decreased dramatically during this period. Twenty four percent of the herds had at least one positive serum in 1995 whereas only 4.5% were positive in 1998. Nevertheless, some new infections still occur. A case control study was carried out in 80 commercial herds to identify and to rank the risk factors which are associated with new infections. Different possible risk factors were assumed and classified regarding into 3 categories according to consecutive steps of contamination of a herd. These 3 categories were: Cases and control herds were chosen out of the population of all herds with at least one serological control per year for 3 consecutive years. These 3 years were from the first of July 1994 to the 30th of June 1997. Both cases and controls were seronegative during the first 2 years. Control herds remained free of infection on the third year. On the contrary, newly infected cases were defined as those herds which became seropositive on the third year. In order to eliminate potential false positives, herds with less than 3 positive sows or 2 positive fatteners were excluded from the analysis. Forty four case herds met these criterion. Forty of them were studied. Seventy percent of the cases were Farrow-to-Finish herds (FAFI), 28% were Feeder-to-Finish herds (FEFI) and the last farm was a Farrow-to-Feeder (FAFE). Controls were individually matched to cases considering their herd type (FAFE, FAFI, FEFI), size (the difference in herd size had to be lower than 30%), location (the control had to be located within 25 kilometres from the case) and producer organisation (in order to facilitate data collection). Variables describing the possible risk factors were obtained (1) with a questionnaire describing the herd and herd management (a single investigator performed the survey in all herds) and (2) by using the regional database which describes the location and the serological status of all herds in Brittany, in order to assess the risk of being contaminated by the neighbourhood. The herd questionnaire contained 95 variables which described the purchase of pigs (9 variables), passive vectors (21), quarantine (8), bio-security (16), herd structure (8) and vaccination scheme (33). Seven variables were calculated to describe the risk associated to neighbourhood. These variables described pig density and the number of infected herds within 1, 3 and 6 kilometre radiuses. The statistical analysis was performed with 2 different stages: Bio-security is an example of a summary variable defined after the first step of analysis. 9 variables are summarised in it. Although the real world is not black and white, large differences between the groups of herds with good or bad bio-securities were observed. Seventy-eight percent of the farms with a good bio-security had a locker and clothes for visitors whereas 79% of the bad group had none. In the same way the good bio-security group was better for locking the door (78% did whereas 90% of the bad group did not), more of them avoided the entry of slaughterhouse lorry drivers within the premises (88% did whereas 62% of the bad group did not). Considering the logistic regression, three risk factors were associated with the new infections: (1) the presence of at least one herd within 1 kilometre from the case ($\rm p = 0.024$, $\rm OR = 5000$); (2) a high number of infected herds between 1 and 6 kilometres ($\rm p = 0.036$, $\rm 0R = 500$). A "high number" was more than 3 infected herds between 1 and 3 kilometres and more than 11 infected herds between 3 and 6 kilometres; (3) the frequency of piglet deliveries ($\rm p = 0.037$, $\rm 0R = 500$). No relation was shown between new infection by Aujeszky's disease virus and other variables including, quarantine, herd-structure, vaccination and bio-security. The results suggest that the two main risk factors for new infection by Aujeszky's disease virus are airborne transmission and purchase of infected piglets. The fact that the other potential risk factors, in particular the quality of vaccination, were not found to be associated with risks of new infection, has to be further discussed. A good vaccination does not prevent herds from being infected by Aujeszky's disease virus. Nevertheless, vaccination remains necessary in high density areas to prevent neighbouring herds from being contaminated by infected herds and to achieve eradication of Aujeszky's disease

Suivi en quasi-temps réel de la vaccination contre la grippe chez les 65 ans et plus en France à partir des ventes de vaccins en pharmacie

National audienceBACKGROUND:The aim of this study was to describe a tool based on vaccine sales to estimate vaccination coverage against seasonal influenza in near real-time in the French population aged 65 and over.METHODS:Vaccine sales data available on sale-day +1 came from a stratified sample of 3004 pharmacies in metropolitan France. Vaccination coverage rates were estimated between 2009 and 2014 and compared with those obtained based on vaccination refund data from the general health insurance scheme.RESULTS:The seasonal vaccination coverage estimates were highly correlated with those obtained from refund data. They were also slightly higher, which can be explained by the inclusion of non-reimbursed vaccines and the consideration of all individuals aged 65 and over. We have developed an online tool that provides estimates of daily vaccination coverage during each vaccination campaign.CONCLUSION:The developed tool provides a reliable and near real-time estimation of vaccination coverage among people aged 65 and over. It can be used to evaluate and adjust public health messages.Position du problèmeL’objectif de cette étude est de décrire un outil permettant d’estimer en quasi-temps réel la couverture vaccinale contre la grippe saisonnière chez les 65 ans et plus à partir des ventes de vaccins en pharmacie.MéthodesLes données de ventes de vaccins proviennent d’un échantillon stratifié de 3004 pharmacies en France métropolitaine et sont disponibles le jour suivant les ventes. Les couvertures vaccinales estimées entre 2009 et 2014 ont été comparées avec celles obtenues à partir des données de remboursements aux affiliés du Régime général.RésultatsLes couvertures vaccinales saisonnières estimées sont très corrélées à celles obtenues avec les données de remboursements. Elles sont aussi légèrement supérieures, ce qui peut s’expliquer par l’inclusion de vaccins non remboursés et la prise en compte de l’ensemble des 65 ans et plus, tous régimes confondus. Nous avons développé un outil accessible en ligne permettant d’accéder quotidiennement à une estimation de la couverture vaccinale des 65 ans et plus lors de chaque campagne de vaccination.ConclusionL’outil développé permet de fournir une information fiable et en quasi-temps réel sur la couverture vaccinale des 65 ans et plus. Il peut être utilisé pour évaluer et ajuster les messages de santé publique

Development of a computerised system for animal health management as a part of an eradication program of Aujeszky's disease

Brittany is the main pig production area in France. About 14 million fatteners are produced a year in this province. There are 9200 farms holding about 690 000 sows. Farrow-to-finish herds are prevalent, representing half of the farms and 70% of the production. More than 4 million piglets are transported per year. An eradication program for Aujeszky's disease is currently in action. The key points of this program are: (1) yearly general serological screening; (2) quarterly blood testing of nucleus and multipliers herds (these herds cannot sell boars and gilts if they are not AD free); (3) compulsory vaccination; (4) a special authorisation needed to move piglets out of non-AD free farms is given by veterinary services. This program involves many organisations. There are four Regional State Veterinary Services (DSV) which are the governmental services at the department level. They manage the eradication plan. Four Departmental Stockfarming Establishments (EDE) are the professional farming bodies with statutory responsibility for identifying stock farms. Twenty-one producer groups (gathering 90% of the farmers and 98% of the fatteners), federated into a union - the UGPVB - organise most transport of piglets, gilts and fatteners. Their importance is a strong characteristic of pig production in Brittany and a key point to understanding the way INFOPORC was built. In addition there are 8 testing laboratories which perform all the serological analyses and 300 field veterinarians. To perform the eradication plan, all the organisations involved have to share information. In particular, a single register of all pig farms, classifying farms according to their health status, identifying animal movement, and producing trend charts and maps is needed. The aim of the INFOPORC information system is to manage all this information, quickly and reliably. The "Association Régionale Interprofessionnelle Porcine" (ARIP) has undertaken, under the general supervision of the French Ministry of Agriculture, Fisheries and Food, to devise, develop and introduce this pilot computerised network for animal health management of pigs. Role of each partner within INFOPORC: The architecture is based on the general principle of a central site and distributed applications. With the exception of the veterinarians, all the active participants connected to the network have a dedicated microcomputer connected to the central. The reference site for the system is the "INFOPORC Node", which is situated in the premises of a specialised computer centre called ARSOE. This site manages the INFOPORC reference database in which the following data are stored: basic data for the INFOPORC system (contact people, livestock farms, etc.), historical records of events managed in INFOPORC (transport, health situation), and data shared or exchanged between different connected computers. All exchanges of information between the different applications integrated into the system are managed by the INFOPORC Node. Each distributed application is linked to the central site by a daily file-exchange procedure. This approach is suited to allow gradual extension of the system. The status of Aujeszky's disease, managed by the DSVs, is transmitted to the producer's groups before transporting pigs in order to check the status of the farms of origin and requirements concerning the introduction of pigs into the farms at destination. After the transport, data entered by the producers groups are automatically transmitted to DSVs. It is therefore possible at any time to search: (1) for the origin or destination of pigs from a given farm (or a given area); (2) for a complete list of transport operations by a given operator; (3) For all herds in a given radius using a Geographical Information System linked to the database. INFOPORC has been in action in the field since May 1998. At present, all movements of piglets (from breeder to finisher or intermediary) are recorded. There are now about 2000 transports registered per month for a total of $400\, 000$ piglets. Historical records of all movements are kept for 5 years. Even if computers will never eradicate any virus, INFOPORC is a useful tool, probably an essential one, for the management of an eradication scheme within a high density pig production area like Brittany. Moreover, such a system will be useful not only for Aujeszky's disease, but also to prevent Classical Swine Fever and other epidemics and to manage Integrated Quality Systems

Epidémiosurveillance de la maladie d'Aujeszky à l'aide de fragments de muscle prélevés à l'abattoir

National audienc

Epidémiosurveillance de la maladie d'Aujeszky à l'aide de fragments de muscle prélevés à l'abattoir

National audienc