OIE: Wildlife Surveillance Key to Biosecurity16 July 2008
GLOBE - Wildlife diseases are of growing concern worldwide. In addition to threatening populations of wild animals themselves, wildlife disease can affect domestic animals and human health, writes OIE Editorial Director, Dr Vallat.
This is particularly true in present days, when emerging diseases shared by both animals and humans increasingly come to our attention in the new context of globalisation of movement of commodities and climate change. Furthermore the legal and illegal market of wildlife which is estimated at a minimum of 6 billion US dollars is growing rapidly and also contributes to the global dissemination of new pathogens and emerging diseases. Therefore, a better understanding of diseases present in wildlife and their effects on wildlife, domestic animals and humans is of key importance to develop control measures.
Zoonoses, which are disease of animals that can infect humans, are a growing concern. Approximately 60% of existing human pathogens and over 75% of those that have appeared during the past two decades can be traced back to animals. Many of them have a proven link with wildlife. Also new factors such as the increasingly mobile human populations, climate change, and the movement of animals and animal products via international trade, deforestation, urbanisation, new social habits such as the increasingly common adoption of exotic pets, all favour the multiplication of unprecedented contacts between wildlife, domestic animals and humans.
The role played by wildlife on the world epidemiological situation is widely demonstrated. We also know that animals in the wild are both targets of and a reservoir of pathogens competent for domestic animals and humans. Infections with Tuberculosis, Nipah virus or Ebola, to name a few, regularly afflict domestic animals and humans likewise and each of these events sounds a strident alarm on the need for better monitoring of wild animal health as well as the source of wildlife diseases. For instance large primates have on occasions seen their wild populations decline due to the incidence of diseases of human origin. More recently, the avian Influenza global crisis has proven how much remains yet to be understood regarding the behaviour of the H5N1 strain in wild birds as well as their role in the spread of the disease.
So called invasive wild and domestic animal species or non-indigenous plants threaten many ecosystems e.g. by introducing alien bodies into some ecological niches with growing negative environmental consequences worldwide. When natural ecosystems are threatened by wild or domestic animal populations which have become wild or semi-wild, it is important to control the demography of such populations which also represent disease reservoirs highly appreciated by numerous pathogens. In this respect, the OIE is looking for setting standards for the humane control of these undesirable categories of animal populations when necessary.
In parallel with the increased human population and the huge rise in world demand for animal proteins which will grow in the coming years, significant increases in domestic animal populations with the attendant requirement for grazing land have caused pastoral activities to impinge on areas inhabited by wild animals in all parts of the world. This creates new challenges for survival of wildlife with a decreased habitat as well as challenging domestic animals with new disease agents.
Management and control of disease in wildlife presents many challenges. Inherent to the definition of wildlife, symptoms and signs of disease are not as readily observed as in domestic animals, specimens for laboratory analysis are more difficult to collect, early detection of and response to disease outbreaks are slow to implement. All these factors combine to make surveillance of wildlife diseases worldwide more problematic but, they certainly do not lessen the importance of surveillance programmes.
The OIE established a permanent working group on wildlife diseases in 1993. The Working Group comprises 6 world-leading scientific experts in their subject areas coming from all regions of the world. They collect, analyse and disseminate information on almost 40 diseases affecting wildlife, whether in the wild or in captivity. It has prepared OIE recommendations and oversees numerous scientific publications on the surveillance and control of the most important specific wildlife diseases.
Surveillance of wildlife diseases must be considered equally important as surveillance and control of diseases in domestic animals. Wildlife often acts as sentinels for animal diseases thus allowing an effective management and control of the diseases in domestic animals. Therefore, the OIE strongly encourages its 172 Members to put efficient monitoring systems in place and notify outbreaks of diseases in wild, feral or partly domesticated animals as is the practice for all other animals. Today, thanks to the world-wide animal health notification system of the OIE (WAHIS), the reporting of animal diseases in the world, including those of wildlife listed by the OIE, has dramatically improved and has brought an unprecedented level of transparency.
All national Delegates of OIE Members have been required to nominate a national focal point who under their authority would declare to the OIE the notifiable diseases affecting wildlife and would submit their comments to the proposals of new standards in the field of wildlife diseases prior to adoption.
Furthermore, the OIE has created the concept of compartmentalisation in order to continue to protect the status of freedom with regard to certain animal diseases of domestic animal populations living in an environment which is affected by these diseases. In some cases, the concept of compartmentalisation allows raising domestic animals and taking part in international trade from areas where wildlife may be infected, e.g. by Newcastle disease in birds or swine fever in boars. On the other hand, it also allows protecting wild animals from some domestic animal diseases thanks to biosecurity measures implemented within the compartments.
The duty of wildlife disease management is clear. We must maintain biological diversity, have better knowledge of animal sanitary statuses and prevent species at risk from disappearing while protecting the human and domestic animal populations from the introduction of diseases. This relies mainly on Veterinary Services. A technically competent, adequately resourced Veterinary Service is needed, working with other regulatory authorities and Non Governmental Organizations in a cooperative constructive manner. This also requires political will and the dedication of the necessary resources for the implementation of programmes and the scientific research. Furthermore, the efficiency of Veterinary Services in this field will be increased by different mechanisms of alliances and collaboration with agencies in charge of wildlife protection and hunting policies, and with NGOs working on same topics. Alliances with hunters' organisations are very useful and important for surveillance and early detection of wildlife diseases. These alliances are also useful for managing non-desirable animal populations.
There have already been notable successes. Some diseases, such as rabies have been controlled or eliminated from many areas thanks to oral vaccination programs - e.g. in foxes- thereby also protecting domestic animals and human health. Rinderpest is on the verge of being eliminated from domestic and wild animals. Trichinellosis while still significant in wild carnivores has been controlled in the domestic swine in most of the world, significantly reducing the incidence of the disease in humans and partially in wildlife.
Wildlife disease problems will not solve themselves. While it is important to monitor the presence of pathogens in wildlife, it is not, and will not be, in wildlife that interventions are mainly directed. Control and eradication measures implemented under the authority of Veterinary Services must primarily focus on domestic animal populations and this will contribute to the protection of wildlife.
The OIE calls the international community as a whole to support national Veterinary Services in order to strengthen their surveillance capacities of diseases in wildlife particularly in order to closely monitor what has the potential to become a threat to domestic animals and eventually to humans. The OIE will also continue to plead to safeguard natural ecosystems together with wild animal species which have survived the planetary upheavals, because they are global public goods.
For all this, the surveillance of wild animal diseases, the sanitary control of international trade of domestic and wild animals and animal products using OIE standards recognized by the World Trade Organisation, as well as the control of non appropriate transfer of invasive species and non desirable animals or plants are essential actions.
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