How and when did besnoitiosis appear in herds in the Auvergne-Rhône-Alpes region?
Romain Persicot : “This emerging disease first appeared in the South West of France. For the past ten years, it has been moving northwards and, in particular, to Auvergne-Rhône-Alpes. It is transmitted by biting insects, but also by the use of multipurpose needles in infected farms. Its expansion remains quite slow, but one of the determining factors is the movement of animals between departments. Some animals carrying the parasite and not detected can be introduced into free areas, sometimes far away, and contaminate them. »
How is the fight once morest this disease organised?
R. P : “There is no mandatory national control strategy for the moment. Nevertheless, at present, all the departments in the region have implemented milk screening, then individual screening when antibodies are found in the tank. For suckler cows, more than half of the departments already set up surveillance via blood screening during prophylaxis. Our priority is above all to detect this disease. For example, the department of Ardèche was a forerunner in terms of monitoring, since breeders carried out numerous screenings. Breeders have an interest in finding this disease, before the rate of contamination increases. »
At the regional level, is it possible to establish the number of animals that have tested positive for besnoitiosis?
R. P : “The strategies of each department are not yet on the same basis, so we cannot consolidate figures. The fight started a few years ago, it is still recent. One thing is nevertheless certain, the disease is slowly taking hold at the regional level. All departments require screening when cattle are introduced and approximately 1 to 2% of animals are screened positive. It is estimated that approximately 10% of herds have at least one positive bovine. Among these herds, 95% of them generally have only one to three positive cattle. In the overall population, the share of positive animals remains quite low for the moment, but that does not mean that it is not serious. If we don’t manage this small percentage as long as it’s still possible, we won’t be able to control it in five or ten years. »
Should cattle positive for besnoitiosis be systematically slaughtered?
R. P : “In a herd, the disease always sets in quite slowly. The objective is therefore to detect quickly, when the spread of the disease within the herd is not excessive. If one, two or three cattle are positive, they must be quickly eliminated, as they constitute a reservoir of the disease. Slaughtering a positive cattle is ultimately an investment for the rest of the herd. Subsequently, it is possible to sell the meat of the slaughtered cattle, since the parasite does not pose a problem for human consumption. »
Is the management of this disease regulated?
R. P : “As of now, there is no cure. This is also why we insist on screening as soon as a new animal is introduced. Besnoitiosis is a parasite. No vaccine exists to date. There are also no regulations currently in force. The only way we have to protect the herd is through biosecurity, nothing else. Biosecurity measures are effective, each breeder already applies a good number of them and they are, moreover, useful for the prevention of all diseases. »
THE BESNOITIOSE / Transmission and symptoms
Besnoitiosis is a disease caused by a parasite from the coccidia group. This is transmitted from cattle to cattle through insect bites (horseflies, stomoxys), or even through the use of multiple-use needles. After inoculation, the parasite multiplies and can invade all the organs. It forms thousands of small parasitic cysts that can persist for the life of the cattle. Although symptoms may affect only a few individuals in a herd, often entire flocks are infected. For symptomatic animals, the disease is generally expressed one week following contamination and includes three successive periods
1 – The febrile phase, which lasts three to ten days. The animal has a high fever (40 to 41°C), is dejected, does not move. Eyes and nose may runny. At this stage, the symptoms may resemble other diseases and it is sometimes difficult to identify besnoitiosis.
2- The edema phase which can last one to two weeks. The temperature then fell but edemas can appear wherever the parasite settles (areas that may have been bitten): head, limbs, under the neck, etc.
3 – The scleroderma phase: the skin dries out, cracks and the animal loses its hair. The evolution of the disease is then inevitable towards the death of the animal. At this stage, only treatments to calm the suffering and avoid infections where the skin is cracking are possible. “In asymptomatic cattle, a sign can also be detected: the presence of cysts on the eyeball. These cysts are an absolute sign of besnoitiosis”, specifies Martin Brusselle, veterinarian of the Health Defense Group of Drôme. To note :
there is no vaccine and no treatment can cure the disease. On the advice of the veterinarian, a treatment with sulfonamides during the first phase of the disease (febrile phase) can make it possible to envisage a favorable evolution. However, the animal will remain a lifelong carrier of the parasite and must be eliminated because it constitutes a reservoir of contagion.
Source : GDS France
Departments affected at different scales
In France, the departments are affected by the disease in different ways. Examples in the Jura and in the Drôme. In the Jura, to detect BVD, IBR and besnoitiosis, 876 serological analyzes on large-mix milk were carried out in 2021. A total of 14 (i.e. 1.6%) were positive. A figure on the increase because in 2022 it rose to 5.8% (53 positive analyzes out of 908 carried out). These results must nevertheless be interpreted with caution, especially when they are close to the positive threshold. According to Martin Brusselle, veterinarian with the Drôme Sanitary Defense Group, the first cases of besnoitiosis identified in the departments date back to the early 2000s. While this disease is indeed present in the department, it is often present in insidious way. According to studies, it is accepted that out of six cattle affected, five will remain asymptomatic. But the situation can deteriorate very quickly, thanks to stress in the breeding. “It is an opportunistic disease which can reappear in carrier animals as soon as another element disrupts the immunity of the herd”, warns Martin Brusselle. The veterinarian also warns of the risk of seeing the disease spread silently, within the herd or to neighboring herds, via insect bites.
SC and SS
