A complex disease that requires an integrated approach
Bovine tuberculosis is an infectious disease transmissible to humans, caused by the bacterium Mycobacterium bovis. France has free status [1] of the disease since 2001 thanks to the control measures put in place in the affected cattle farms. However, some outbreaks of infection persist in certain departments and are now subject to specific monitoring and management measures to maintain this status. Beyond cattle farms, many wild animal species are susceptible to infection, such as deer, wild boar and badgers. Thus, the possibilities of exchanges of the bacterium between domestic fauna and wild fauna can partly explain the persistence of certain residual foci and have led to the application of measures both in breeding and in wild animals. In addition, recent research has shown that the bacterium was resistant in the environment (burrows, pastures) and indirect contamination of cattle is also possible. The epidemiological situation of bovine tuberculosis is the result of complex interactions between several host species: cattle, wild animals and the environment, which implies adopting a comprehensive One Health approach to surveillance and control. this disease.
The badger and bovine tuberculosis
The badger is one of the wild species susceptible to bovine tuberculosis. It is a difficult species to study because of its way of life in burrows and its nocturnal behavior. The transmission of the bacterium between badgers, and between badgers and other animal species, depends in particular on the number of direct or indirect contacts between animals and the densities of their populations. Due to the highly variable behavior of badger populations, comparisons between regions and countries should be analyzed with caution. It is always necessary to carry out investigations locally, on a case-by-case basis. Studies conducted in France confirm that the badger plays a role in the epidemiological cycle of tuberculosis in Côte-d’Or. Elsewhere on our territory, this role remains to be clarified, even if the historical data tend to confirm this same hypothesis.
Measures adapted to the terrain
Following recommendations from ANSES in 2011, a surveillance system for bovine tuberculosis in wildlife, Sylvatub, was set up in France. Today integrated into the Animal Health Epidemiological Surveillance Platform (ESA), this system consists of monitoring the evolution of the disease and precisely locating the areas at risk around the outbreaks of infected cattle farms where contacts are possible with wildlife. Thanks to the collection of these data, it is possible to constantly adapt control measures in wildlife in order to eradicate the disease in cattle farms.
The current regulations precisely frame the surveillance and control measures leading to the elimination of wild animals, depending on the levels of infection and the areas. As such, measures in badgers can only be implemented in a delimited area, determined and regularly reassessed according to monitoring data. In addition, operations are preceded by a census of badger burrows in this area. These control measures only concern areas at risk in a few departments in France, which in 2018 represented less than 4% of the metropolitan territory. Concerning other types of measures, the vaccine solution is currently at the experimental stage and ANSES is associated with research work on the development of an oral vaccine.
Following an analysis of current control measures, ANSES confirms that only coordinated actions can effectively control bovine tuberculosis, targeting both cattle on infected farms and wild animals, as well as the environment. near. At present, these measures do not threaten the badger species on a national scale. The experts, however, recalled their 2011 recommendations that in disease-free areas, the preventive removal of badgers and other wildlife cannot under any circumstances be justified on the grounds of the fight once morest tuberculosis.
[1] Criteria for freedom from bovine tuberculosis:
- the annual prevalence of infected herds is less than 0.1% for six years;
- the rate of officially free herds is greater than 99.9% for six years as of December 31 of each year;
- European regulations on tuberculosis (Directive 64/432) are respected.
