Defining an emerging disease.

Defining an emerging disease is not straightforward, as there are several different types of disease emergence. For example, there can be a 'real' emergence of a brand new disease, such as the emergence of bovine spongiform encephalopathy in the 1980s, or a geographic emergence in an area not previously affected, such as the emergence of bluetongue in northern Europe in 2006. In addition, disease can emerge in species formerly not considered affected, e.g. the emergence of bovine tuberculosis in wildlife species since 2000 in France. There can also be an unexpected increase of disease incidence in a known area and a known species, or there may simply be an increase in our knowledge or awareness of a particular disease. What all these emerging diseases have in common is that human activity frequently has a role to play in their emergence. For example, bovine spongiform encephalopathy very probably emerged as a result of changes in the manufacturing of meat-and-bone meal, bluetongue was able to spread to cooler climes as a result of uncontrolled trade in animals, and a relaxation of screening and surveillance for bovine tuberculosis enabled the disease to re-emerge in areas that had been able to drastically reduce the number of cases. Globalisation and population growth will continue to affect the epidemiology of diseases in years to come and ecosystems will continue to evolve. Furthermore, new technologies such as metagenomics and high-throughput sequencing are identifying new microorganisms all the time. Change is the one constant, and diseases will continue to emerge, and we must consider the causes and different types of emergence as we deal with these diseases in the future.

OASIS: an assessment tool of epidemiological surveillance systems in animal health and food safety.

The purpose of this study was to develop a standardized tool for the assessment of surveillance systems on zoonoses and animal diseases. We reviewed three existing methods and combined them to develop a semi-quantitative assessment tool associating their strengths and providing a standardized way to display multilevel results. We developed a set of 78 assessment criteria divided into ten sections, representing the functional parts of a surveillance system. Each criterion was given a score according to the prescription of a scoring guide. Three graphical assessment outputs were generated using a specific combination of the scores. Output 1 is a general overview through a series of pie charts synthesizing the scores of each section. Output 2 is a histogram representing the quality of eight critical control points. Output 3 is a radar chart representing the level reached by ten system attributes. This tool was applied on five surveillance networks.

A qualitative risk assessment methodology for scientific expert panels.

Risk assessment can be either quantitative, i.e. providing a numeric estimate of the probability of risk and the magnitude of the consequences, or qualitative, using a descriptive approach. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES), formerly the French Food Safety Agency (AFSSA), bases its assessments on the opinions of scientific panels, such as the ANSES Animal Health Scientific Panel (AH-SP). Owing to the lack of relevant data and the very short period of time usually allowed to assess animal health risks on particular topics, this panel has been using a qualitative risk method for evaluating animal health risks or crises for the past few years. Some experts have drawn attention to the limitations of this method, such as the need to extend the range of adjectives used for the lower probabilities and to develop a way to assess consequences. The aim of this paper is to describe the improved method now established by the AH-SP, taking into account the limitations of the first version. The authors describe a new set of levels for probabilities, as well as the items considered when addressing either animal or human health consequences.

Invasive mammals.

Every region of the world is concerned by potential mammal invasions, as humans are already present on all the world's land masses. All these invasions are a result of species introductions by humans for one reason or another. The authors briefly review the known movements and observed consequences of mammal-related invasions. They take examples from all five continents, as well as from a few island systems. The ancient introduction of game species, and later of domestic species, has been followed more recently by movements of commercial species. We are now seeing the emergence of what are known as entertainment species. In a number of cases, such introductions have led to the establishment of new epidemiological cycles that previously might never have been thought possible. According to current indicators, this phenomenon is not on the wane.

Invasive reptiles and amphibians.

Although they are frequently lumped together, reptiles and amphibians belong to two very different zoological groups. Nevertheless, one fact is clear: while numerous reptile and amphibian species on Earth are in decline, others have taken advantage of trade or human movements to become established in new lands, adopting different, and sometimes unusual, strategies. The authors have taken a few examples from these two zoological groups that illustrate the majority of cases. A brief analysis of the causes and effects of their introductions into new areas reveals connections with economic interests, trade in companion animals, medical research and public health.

Why own an exotic pet?

Even though people have owned a wide variety of companion animals since times of old, the modern craze for increasingly exotic and little-known species raises a number of questions, including some of an ethical nature. While trade in exotic animals is certainly profitable for these who practise it, it poses great risks of varying types: ecological risks, threats to biodiversity conservation and health risks. Several introduced animal populations have gone on to establish a line in their new host country. We are just starting to measure the adverse impact this has had, in some cases on a very large scale. The veterinary profession doubtless has a major role to play in endeavouring to reform this trade in living creatures that unfortunately results in many losses.

Invasive species. Part 1: general aspects and biodiversity. Part 2: concrete examples.

The problem of invasive species is of interest to researchers in a variety of different fields, including biology, epidemiology, agriculture, public health and even human sciences. It is an issue that affects all regions of the world to a greater or lesser extent. It can also have detrimental effects on animal health and biodiversity. For example, the International Union for the Conservation of Nature (lUCN) reported that 625 (51%) of known endangered species are threatened because of invasive (alien) species.

Defining an invasive species.

The definition of an invasive species will depend on the viewpoint of the observer, who in some cases may be responsible for introducing the species. History has taught us that humans are the species that has invaded the largest surface area of the planet. So, before going on to propose a few definitions, this article describes three different examples or types of example in which domestic animal species, wild animal species and microorganisms (for biological pest control) have been transported intentionally. By doing so, this paper uses a variety of situations to support the definitions. A contemporary argument would counter a strictly biogeographical definition with a more ecological definition. The two are probably complementary. In any case, these definitions should remain practical. The consequences of species movements vary. However, their health impacts should not be underestimated.

Geographical distribution of domestic animals: a historical perspective.

Our understanding of the history of animal domestication has been built on regular input from archaeozoology. This fast-expanding discipline uses increasingly sophisticated and specialised tools to enhance our knowledge of phenomena dating back, for the oldest species, to the Neolithic Revolution. This article takes three examples, those of the domestic dog, domestic goat and European rabbit, to illustrate the history of three different domestication processes using the contemporary means available. In each of the three cases, the authors define the location of original domestication, analyse the principal routes of species movements following domestication, discuss the possible reasons for domestication and suggest a few likely epidemiological impacts.

Global change: impact, management, risk approach and health measures--the case of Europe.

Global changes, including an increase in trade and global warming, which act on the environment, are likely to impact on the evolution of pathogens and hence of diseases. To anticipate the risks created by this new situation, a French group of experts has developed a method for prioritising animal health risks. This is a two-phase method: the first step is to identify the diseases whose incidence or geographical distribution could be affected by the changes taking place, and the second step is to evaluate the risk of each of these diseases. As a result of this process, six priority diseases were selected: bluetongue, Rift Valley fever, West Nile fever, visceral leishmaniasis, leptospirosis and African horse sickness. The main recommendations were: to develop epidemiological surveillance, to increase knowledge of epidemiological cycles, to develop research into these diseases and to pool cross-border efforts to control them.

Patterns of lesions of bovine tuberculosis in wild red deer and wild boar.

The data obtained from a survey of Mycobacterium bovis infection in wild red deer (Cervus elaphus) and wild boar (Sus scrofa) conducted in France in the 2005/06 hunting season were used to describe and quantify the pathological findings in the two species. The red deer had caseous abscessed lesions in their organs and lymph nodes, whereas in the wild boar the lesions were predominantly caseocalcareous and occurred mainly in the lymph nodes. The severity of the gross tuberculosis-like lesions was estimated on the basis of a numerical score. The significant difference between the distribution of the scores in the two species indicated that the disease was more serious in the red deer than in the wild boar. Unlike the red deer, the wild boar did not show a generalised pattern of disease. Among the lymph nodes examined systematically, gross lesions were most frequently observed in the mesenteric lymph nodes in the red deer and in the retropharyngeal lymph nodes in the wild boar. In both species, the presence of gross lesions showed the closest agreement with the isolation of M bovis from the same lymph nodes. The different patterns of the lesions of tuberculosis in the two species suggest that red deer might play an important role in the intraspecies and interspecies dissemination of the infection, whereas in wild boar the spread of the infection would be more likely to be restricted to other wild boar.

[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.

[Chronic wasting disease of cervidae]. / La maladie du dépérissement chronique des cervidés : une forme d'EST ancienne mais encore bien mal connue.

Chronic wasting disease (CWD) of cervidae, only known in three North American species of cervids, is one the oldest known of the prion diseases or transmissible spongiform encephalopathies (TSEs), and the only one naturally present in wild populations. The interest linked toCWDis quite new, linked to the European mad cow disease crisis. This review puts together the facts associated with the disease, trying to put forward its specificities and looking for possible developments. Even if known since quite a long time this TSE is still one of the least understood. It does represent a different disease. Some of the difficulties facing its study are linked to the fact that it concerns free-ranging wild species. Epidemiological and sanitary consequences are presented.

Ring vaccination against foot-and-mouth disease.

The study of the available information, notably after the epizootic of foot-and-mouth disease (FMD) which raged in Western Europe in 2001, shows that, in the current conditions of the international sanitary rules relative to this disease, in a FMD-free country of Western Europe accidentally infected, ring vaccination is a solution which, with regard to preventive slaughter, contains more inconveniences (notably economic) than advantages. The appeal to ring vaccination would be interesting only as far as the international sanitary rules would be modified by taking into account the results expected from the coordinated use of highly purified vaccines and differential research kits (vaccine-linked versus infection-linked antibodies). Propositions are this way made.

A point pattern model of the spread of foot-and-mouth disease.

The spatial spread of foot-and-mouth disease (FMD) is influenced by several sources of spatial heterogeneity: heterogeneity of the exposure to the virus, heterogeneity of the animal density and heterogeneity of the networks formed by the contacts between farms. A discrete space model assuming that farms can be reduced to points is proposed to handle these different factors. The farm-to-farm process of transmission of the infection is studied using point-pattern methodology. Farm management, commercial exchanges, possible airborne transmission, etc. cannot be explicitly taken into account because of lack of data. These latter factors are introduced via surrogate variables such as herd size and distance between farms. The model is built on the calculation of an infectious potential for each farm. This method has been applied to the study of the 1967-1968 FMD epidemic in UK and allowed us to evaluate the spatial variation of the probability of infection during this epidemic. Maximum likelihood estimation has been conducted conditional on the absence of data concerning the farms which were not infected during the epidemic. Model parameters have then been tested using an approximated conditional-likelihood ratio test. In this case study, results and validation are limited by the lack of data, but this model can easily be extended to include other information such as the effect of wind direction and velocity on airborne spread of the virus or the complex interactions between the locations of farms and the herd size. It can also be applied to other diseases where point approximation is convenient. In the context of an increase of animal density in some areas, the model explicitly incorporates the density and known epidemiological characteristics (e.g. incubation period) in the calculation of the probability of FMD infection. Control measures such as vaccination or slaughter can be simply introduced, respectively, as a reduction of the susceptible population or as a reduction of the source of infection.

Foot and mouth disease: lessons to be learned from the experience of France.

The appearance of foot and mouth disease (FMD) in the United Kingdom in late February 2001 took European veterinary services by surprise. Differences in the types of measures taken by European countries, and in the speed with which they were implemented, partly explain the different animal health situations observed. France, as a major importer of British sheep, is an interesting country to study. The measures taken there are described in detail, as is the history of the two cases registered on 13 and 23 March 2001. The crisis management procedure is also detailed. The majority of the decisions taken and protocols followed are part of the national intervention plan for FMD. However, experience has shown that it is also important to remain pragmatic and to be able to adapt to new developments during the implementation of the plan. While pre-emptive killing may indeed have reduced the number of outbreaks in France, the social impact of such measures also needs to be taken into account in the development of animal health policy.

[Wild animals, sentinels of the pollution of the natural environment?]. / Les animaux sauvages, sentinelles de la pollution du milieu naturel?

By following the cycles of contaminants in the environment, it is possible to demonstrate the existence of species particularly sensitive to certain substances through their diet, behaviour or location. Analysis of such situations can lead to the use of the species to provide evidence of the burden of pollution of an ecosystem. The existence of threshold concentrations, above which certain phenomena may occur, strengthens the role of sentinels. Examples are drawn mainly from mammals, birds and fish, and concern radionuclides, plant protection chemicals, petroleum hydrocarbons and heavy metals. The list is by no means exhaustive.

A qualitative assessment of the risk of introducing foot and mouth disease into Russia and Europe from Georgia, Armenia and Azerbaijan.

A qualitative risk assessment was performed to evaluate the risk of introducing foot and mouth disease (FMD) virus into Russia and the rest of Europe from the countries of Transcaucasia (Armenia, Azerbaijan and Georgia). The assessment was based on data collected during a three-week mission to these countries by the Food and Agriculture Organization, the European Union and the Office International des Epizooties in March 1999. Due to the strong involvement of the local veterinary services, much information was obtained. Although the data were not sufficient to allow a quantitative risk assessment to be performed, the investigation served as a useful initial approach, prior to undertaking a quantitative risk assessment. The risk of FMD virus infection is a function of two elements, namely: the probability of the hazard (virus infection) occurring, and the magnitude of the consequences. The probability of the hazard occurring is the product of the probability of entry of the virus and the probability of exposure to the virus. These elements were assessed using the following parameters: prevalence of infection; volume of trade; capacity of the virus to survive; and potential for infection. The magnitude of the consequences is derived from the probability of transmission and spread. Combining these parameters, the probability of occurrence of the hazard was rated as 'moderate'. Economic consequences of potential transmission and spread of FMD, in the local context, were rated as 'negligible'. As a result, the overall risk of introducing FMD virus into Russia and the rest of Europe from Trancaucasia was rated as 'low' at the time of evaluation. The method and results are presented to serve as a basis for further discussion.

The 1993 Italian foot-and-mouth disease epidemic: epidemiological features of the four outbreaks identified in Verona province (Veneto region).

Imported cattle gave rise to an epidemic of foot-and-mouth disease (FMD) in Italy during 1993. Four outbreaks occurred in large housed beef herds in Verona province. Investigations revealed that there were no movements of livestock out of the infected premises and meteorological analyses suggested that the airborne spread of infectious particles had been limited by the anticyclonic conditions. Surveillance was therefore concentrated on the areas immediately surrounding the outbreaks and the infection was prevented from spreading.