Incursions of foot-and-mouth disease virus into Europe between 1985 and 2006.

Foot-and-mouth disease (FMD) is one of the biggest threats to animal health in European countries. In the last 22 years (1985-2006), FMD has occurred 37 times in 14 European countries. Serotype O was most frequently involved in these outbreaks followed by A, C and Asia 1. Sometimes, epidemics were very limited and at other times, they were the cause of devastating economic losses. In most cases (22/37), the origin of the outbreaks could not be determined. For some of these outbreaks, however, routes of introduction and spread were identified through epidemiological inquiries. Moreover, in some cases, the origin of the virus was also traced by phylogenetic analysis of the partial or complete sequences of VP1 genes. Lessons learned from the outbreaks are still useful as most of the same risk factors persist. However, efforts made by FMD-free countries to help those where the disease is endemic are a valuable strategy for the reduction of the global risk. The present and the future potential sources of FMD infection need to be identified to best focus European efforts.

Epidemiological patterns of foot-and-mouth disease worldwide.

Foot-and-Mouth Disease (FMD) is a clinical syndrome in animals due to FMD virus that exists in seven serotypes, whereby recovery from one sero-type does not confer immunity against the other six. So when considering intervention strategies in endemic settings, it is important to take account of the characteristics of the different serotypes in different ecological systems. FMD serotypes are not uniformly distributed in the regions of the world where the disease still occurs. For example, the cumulative incidence of FMD serotypes show that six of the seven serotypes of FMD (O, A, C, SAT-1, SAT-2, SAT-3) have occurred in Africa, while Asia contends with four sero-types (O, A, C, Asia-1), and South America with only three (O, A, C). Periodically there have been incursions of Types SAT-1 and SAT-2 from Africa into the Middle East. This paper describes the global dynamics for the seven sero-types and attempts to define FMD epidemiological clusters in the different regions of the world. These have been described on a continent by continent basis. The review has reaffirmed that the movement of infected animals is the most important factor in the spread of FMD within the endemically infected regions. It also shows that the eco-system based approach for defining the epidemiological patterns of FMD in endemic, which was originally described in South America, can apply readily to other parts of the world. It is proposed that any coordinated regional or global strategy for FMD control should be based on a sound epidemiological assessment of the incidence and distribution of FMD, identifying risk sources as either primary or secondary endemic eco-systems.

Planning for the progressive control of foot-and-mouth disease worldwide.

In the wake of on-going successful programmes for global eradication of rinderpest and the current effort to contain the spread of avian influenza, the progressive world-wide control of FMD must be regarded as a major contribution to the international public good. FMD is the single most animal disease constraint to international trade in animal products. Its control is relevant, on the one hand, to protecting the livestock industries of industrialised countries and, on the other, to the livelihoods and income generation of developing countries, where, as a general rule, FMD continues to be endemic. The strategy that is advocated in this paper is one that is based on progressive risk reduction of FMD in the context of progressive market access of livestock commodities from developing countries. It is suggested that FMD control should be linked to improvement in livelihoods of livestock dependent communities in the FMD endemic settings. It is expected that this in turn will lead to increasing demand for effective national veterinary services and disease surveillance. This strategy has also taken lessons from the global rinderpest eradication programme and regional FMD control programmes in Europe and South America. The strategy that is advocated for the progressive control of FMD in the endemic settings is based on a seven stage process within a horizon of about 30 years, namely: (1) Assessing and defining national FMD status; (2) instituting vaccination and movement control; (3) suppressing virus transmission to achieve absence of clinical disease; (4) achieving freedom from FMD with vaccination in accordance with the OIE standards; (5) achieving freedom from FMD without vaccination in accordance with the OIE standards; (6) extending FMD free zones; and (7) maintaining FMD Freedom. Concomitant with progressive FMD control, there needs be the encouragement of such risk reduction measures as in-country commodity processing in order to encourage regulated trade in livestock commodities without unduly increasing the risk of disease spread. Finally, the progressive control of FMD should also be seen as part of reducing the overall, world-wide threat of infectious diseases to human health and economic development.

[Survey of foot and mouth disease in France]. / Le système de surveillance de la fièvre aphteuse en France.

The Foot and Mouth disease is considered a relatively mild disease in susceptible animals but it has a considerable economical impact in France and worldwide due to the huge economical losses that it generates. A system for the prevention of the disease was developed thirty years ago and has since been continuously improved. The current system for the prevention of FMD is based on training and information of all those involved in the surveillance of susceptible animals, over all the national territory, and on the control of imported animals and animal products. This system, developed in close collaboration with the European Commission and the other EU member states, allows control measures to be implemented almost instantaneously, if a case is suspected to avoid spreading of the disease.

Estimating the risk of importation of foot-and-mouth disease into Europe.

The opinions of a number of recognised world experts on foot-and-mouth disease (FMD) were sought in order to answer key questions relating to the importation of the disease into European countries from countries outside Europe. In addition, their opinions were sought on where in Europe a primary outbreak of FMD was most likely to occur and the number of outbreaks likely to occur within European countries in the next five years. The Balkans group of countries was considered to be the most likely group within Europe to have a primary outbreak of FMD and also most likely to have the highest number of primary outbreaks. Turkey was considered to be the country outside Europe which was most likely to be the source of an outbreak within Europe as a whole, and the illegal importation of livestock was considered to be the most likely route of introduction of FMD into Europe. Results specific to the Islands group of countries, which included the UK and Ireland, suggested that this group was likely to have a mean of one primary outbreak of FMD in the five years from September 2000, and that the importation of foodstuffs by people entering those countries from Turkey was the most likely source of an outbreak.

Review of the status of foot and mouth disease and approach to control/eradication in Europe and Central Asia.

The authors describe the situation of foot and mouth disease (FMD) in Europe over the past 70 years and analyse the origin of the disease and methods of control, particularly since preventive vaccination was banned in Europe in the early 1990s. Since then, and until 2001, despite several incursions of the virus, the disease has always been contained and eradicated rapidly. Therefore, the ban on vaccination did not result in an increase of FMD outbreaks. However, the massive outbreak which took place in 2001 in the United Kingdom (UK) with 2,030 outbreaks, raised questions on the policy utilised to date to control the disease in Europe. In future, the utilisation of ring vaccination should be considered as an alternative to mass culling of large numbers of animals. Based on the recent source of introduction of the virus, the authors review the lines of defence which should be reinforced to reduce the risk of further introduction of the disease. The FMD situation in the Commonwealth of Independent States (CIS) is also examined. The situation in the Central Asian Republics and the Caucasian region deteriorated after the collapse of the Soviet Union, despite the continuous effort of Russia to support these countries. International support is needed to prevent FMD from becoming endemic in the region.

How predictable were the outbreaks of foot and mouth disease in Europe in 2001 and is vaccination the answer? / L'épisode de fièvre aphteuse en Europe en 2001 était-il prévisible? La vaccination constitue-t-elle une solution?

The author raises three important questions on the outbreaks of foot and mouth disease (FMD) in Europe in 2001: were these linked to stopping preventive vaccination, could these outbreaks have been forecast and were they avoidable, and is vaccination an efficient tool to control outbreaks? The replies to these questions are based on recent history of FMD in Europe. The author demonstrates that the 2001 outbreaks were not linked to ceasing vaccination in Europe in 1991. He also attempts to understand the reasons which encouraged the United Kingdom not to use vaccination to halt the progression of the disease, despite the clear demonstration that vaccination is a useful tool in arresting the spread of an epidemic. In conclusion, the author suggests that substantial changes to European policy for FMD control used for the past ten years are not necessary, but that recourse to emergency vaccination should be considered as an important control option in the future. This option should be optimised by ensuring that differential serological tests are performed in parallel with emergency vaccination, thereby enabling the identification and subsequent elimination of infected herds.

A serological survey on classical swine fever (CSF), Aujeszky's disease (AD) and porcine reproductive and respiratory syndrome (PRRS) virus infections in French wild boars from 1991 to 1998.

In early 1992, a CSF epizootic was clinically recognised in a wild boar population of approximately 1300 animals within an area of 250km(2) located in the east of France. In order to check the CSF situation in wild boars outside this area, a serological survey was carried out in the rest of France, for 8 consecutive years (1991-1998). This paper reports on the results obtained during this survey which included wild boars shot during the hunting period but also boars reared within fences. Around 1000-2700 sera a year were tested for the presence of antibodies to classical swine fever virus (CSFV) and also to Aujeszky's disease virus (ADV). Out of 12025 sera tested over the whole period, 80 wild boars were found positive for CSF antibodies. Sixty of them were collected on wild boars shot during the years 1992-1994 in the epizootic area located in east of France and 10 were collected in Corsica during the years 1994-1996. The last four positive samples were single reactors coming from areas or farms, which were thereafter confirmed to be serologically negative. These results together with the fact that no disease has been reported so far illustrate that the French wild boar population is probably not concerned by CSF infection (excepted in the east of France where the disease has now become enzootic). Two hundred and forty nine sera were initially detected as CSF positive but confirmed secondarily as positive for border disease (BD) antibodies. This finding shows that wild boars are also susceptible to infection by ruminant pestiviruses. Four hundred and twenty three wild boars have been found positive for ADV antibodies. In addition, from 1993 to 1995, 909 samples were tested for the presence of antibodies to porcine reproductive and respiratory syndrome virus (PRRSV). Thirty three of them were positive. The results on AD and PRRS antibody detection show that wild boars may constitute a reservoir for various infectious diseases of pigs.

Prevention measures against foot-and-mouth disease in Europe in recent years.

The paper describes the situation of foot-and-mouth disease in Europe over the past 2 years and analyses the origin of the disease during the last decades. Preventive vaccination has been banned in Europe in the early nineties. Since then, despite several incursion of the virus, the disease has always been rapidly contained and eradicated. Therefore the ban on vaccination did not result in an increase of FMD outbreaks. Based on the recent source of introduction of the virus, the author reviews the lines of defence which should be reinforced to reduce the risk of further introduction of the disease.

[Epidemiologic study of bluetongue in sheep, cattle and different species of wild animals in the Ivory Coast]. / Etude épidémiologique sur la fièvre catarrhale du mouton chez les ovins, les bovins et différentes espèces d'animaux sauvages en Cóte d'Ivoire.

Between 1992 and 1993, a serological survey was conducted in Côte d'Ivoire on 623 sera from sheep, 215 sera from cattle and 211 sera from wild herbivores. These sera were tested for bluetongue virus (BTV) antibodies using an agar gel immunodiffusion test. The purpose of this survey was twofold: to establish the incidence of bluetongue in the country, and to analyse the putative role of BTV in the reproductive pathology of sheep. Seroprevalence was 52 +/- 4% in sheep, 95 +/- 3% in cattle, and 56 +/- 7% in wild herbivores. The authors found antibodies against BTV in kob (Kobus kob Erxleben, 1777), common waterbuck (Kobus ellipsiprymnus Ogilby, 1833), roan antelope (Hippotragus equinus Desmarest, 1804), buffalo (Syncerus caffer Sparrman, 1779), hartebeest (Alcelaphus buselaphus Pallas, 1766) and elephant (Loxodonta africana Blumenbach, 1797). A significant difference was found in seroprevalence in sheep between the three areas covered by the survey. Antibody prevalence increased significantly with age in sheep and wild herbivores, and seroprevalence was higher in dams with a history of abortion. It can therefore be concluded that bluetongue is enzootic in Côte d'Ivoire.

[Prevalence of Trypanosoma infections in different species of wild animals in the Comoé national park on the Ivory Coast: preliminary results of the comparison of 3 diagnostic methods]. / Etude de la prévalence des infections à trypanosomes chez différentes espèces d'animaux sauvages du parc national de la Comoé en Côte d'Ivoire: résultats préliminaires sur la comparaison de trois méthodes de diagnostic.

Compared with the numerous studies of trypanosomosis in domestic animals, few such studies have been carried out on wild animals in West Africa. Preliminary results on the comparison of three detection methods (thin smears, detection of trypanosome antigens by ELISA-Test and Kit for in vitro isolation of trypanosomes, KIVI) in wild animals of Comoe Game Reserve in Côte d'Ivoire confirm the actual presence of trypanosomes; however, no accurate identification of those parasites has been possible, but work is in progress to clarify the taxonomical status of stocks isolated by KIVI.

An attempt at measuring health in nucleus and multiplier pig farms.

A pilot epidemiological inquiry was undertaken in France in a group of 205 nucleus and multiplier pig farms. The aim was to find out a method for a quantitative evaluation of the health level in farms selling young breeders. An exhaustive protocol was prepared for data collection. The sources of information were clinical inspections on the farms, meat inspection data at slaughter and laboratory investigations. Data processing issued in the selection of a profile made of 14 prevailing health indicators. These were then associated so as to set up a health index with an overall score. In a second phase, the relevance of the method with respect to disease transmission was assessed. The principle was a contact challenge within totally controlled facilities between SPF pigs hysterectomy-derived and gilts taken from farms with different health scores as previously checked. The contact lasted for 28 days. Eleven farms were chosen and in every one of them 7 gilts were sampled and 10 SPF pigs were assigned to each of these farms. All the pigs were submitted to a detailed observation. At the end of it the pigs were euthanized at the laboratory and checked to find out any lesions and infectious agents. A wide range of symptoms appeared among the SPF pigs. Mortality rate was 14.6%. Pneumonia affected 23.7% of them. A relationship was found between the germ transfer and the severity of the troubles. The degree of illness in SPF pigs was clearly related to the score obtained previously in the corresponding farms. Consequently, the method was considered as valid with respect to health evaluation.

Une ensute épidémiologique pilote est conduite en France dans un groupe de 205 élevages de sélection et de multiplication. Le but est de contribuer à la mise au point d'une méthode permettant une évaluation quantitative du niveau sanitaire des élevages. Le protocole appliqué permet une collecte exhaustive d'informations à partir d'examens cliniques réalisés en élevage, d'examens de lésions sur porcs en abattoir et à partir de recherches de laboratoire. Le traitement statistique des données a permis de sélectionner 14 indicateurs de santé prépondérants. Ces deniers sont ensuite combinés pour former un index de santé. Un score peut alors t̂re attribué à chaque élevage. An cours d'une seconde phase, la pertinence de la méthode en regard du risque de transmission de maladies par les jeunes reproducteurs dans un élevage d'accueil a été testée dans des conditions expérimentales standardisées et totalement contrôlées. Le principe est un "contact" entre des porcs SPF et des cochettes prélevées dans des élevages ayant obtenu des scores différents pour leur état de santé. Le contact dure 28 jours. Onze élevages ont été choisis. Dans chacun d'eux 7 cochettes sont prélevées et mises au contact de 10 porcs SPF. Tous les animaux sont soumis en station expérimentale à une observation détaillée. Au terme de la période, tous les porcs sont euthanasiés et des recherches complètes sont entreprises. Des symptômes variés sont apparus sur les porcs SPF. Le taux de mortalité en cours d'essai a été de 14.6%. Des lésions de pneumonie ont été décelées sur 23.7% des porcs. Une relation est apparue entre le transfert des contaminants et la sévérité des signes cliniques. La sévérité du challenge chez les porcs SPF était bien corrélée au niveau sanitaire global des élevages fournisseurs des cochettes. La méthode d'évaluation du niveau sanitaire est donc considérée comme satisfaisante en regard des objectifs fixés.La signification de l'outil épidémiologique pour estimer la pression d'infection dans les élevages est discutée.

Characterization and pathogenicity for pigs of a hog cholera virus strain isolated from wild boars.

One hog cholera virus strain isolated from an outbreak of the disease in a wild boar breeding herd in Brittany (France) in 1990 has been characterized with a panel of monoclonal antibodies to hog cholera virus and ruminant pestiviruses: the strain was found to be indistinguishable from that of other domestic pig isolates. The pathogenicity of the strain to domestic pigs was evaluated by infecting intranasally, intramuscularly and by contact 17 specific pathogen-free 6-week- and 12-week-old pigs. Sixteen of the 17 pigs showed symptoms of hog cholera. The virus was detected in the blood of the 16 pigs during all phases of hyperthermia which persisted up to death or the terminal phase, ie between 16 and 29 days post-infection. One animal recovered after presenting a mild form of the disease. This pig was the only one which raised antibodies to the virus. Typical hog cholera lesions were observed in 2 pigs only; the other animal showed very few pathological changes. No relationship between intensity or duration of the disease and pathological changes could be established.

Protection of piglets born from ruminant pestivirus experimentally infected sows, and their contacts, to the challenge with hog cholera virus.

Two groups, A and B, of two specific pathogen-free pregnant sows were experimentally infected between the 25th and 29th days post-breeding with two strains of ruminant pestivirus: NADL cytopathic bovine viral diarrhoea virus for group A and Aveyron non-cytopathic border disease virus French strain for group B. Two other pregnant sows (group C) were kept uninoculated as control. When 7 weeks old, 8 piglets of group C were put in contact with 4 piglets of group A (group D), and 8 other piglets of group C with 4 piglets of group B (group E) in two separate pens with the purpose of testing the horizontal transmission of the viruses. All animals were kept under observation and serologically controlled at weekly intervals; two pigs of each group were finally submitted to a challenge with hog cholera virus. The two pigs of group E which were put in contact with the offspring of the border disease virus infected sow were protected; all other animals developed typical hog cholera symptoms and died. The relation between neutralizing titres of the sera to ruminant pestiviruses and protection to the challenge with hog cholera virus is discussed. The two protected pigs had high neutralizing antibody titres to border disease virus but no antibody to hog cholera virus at the time of the challenge. Though the two viruses look serologically distant, we surprisingly observed that infection with border disease virus protects against a superinfection with hog cholera virus.

An enzyme linked immunosorbent assay (ELISA) for the detection of antibodies to the porcine reproductive and respiratory syndrome (PRRS) virus.

An indirect enzyme-linked immunosorbent assay (ELISA) has been developed for the rapid detection of antibodies to the porcine reproductive and respiratory syndrome (PRRS) virus in pig sera. Compared to the immunoperoxidase monolayer assay (IPMA) which was the only test available up till recently for serodiagnosis of the disease, the ELISA test proved to be more sensitive, particularly for early detection of antibodies. The test was also highly specific for the PRRS virus inasmuch as it scored negative all the hyperimmune sera directed to other swine viruses and the field sera sampled before the outbreak of the disease in Brittany (France). This easy test now provides further possibilities for epidemiological surveys and could also be a reliable tool for new sanitary prophylaxis of the disease.

Report on the first outbreaks of the porcine reproductive and respiratory syndrome (PRRS) in France. Diagnosis and viral isolation.

We describe the first known occurrence in France of the porcine reproductive and respiratory syndrome (PRRS), a new porcine disease that first appeared in Germany in November 1990. Outbreaks of the disease appeared in November 1991 in Brittany (France), with comparable clinical features to those observed in other countries, were definitively confirmed by a serological analysis from the affected animals using an immunoperoxidase monolayer assay with PRRS-virus infected alveolar macrophages. Furthermore, we report the isolation from one serum of a filtrable agent that, in view of its cytopathic effect for porcine alveolar macrophages and of the serologic reactivity of the infected cells, appears similar to the Lelystad virus that has been implicated in the etiology of the disease.