This farm is accumulating cases: two cows died in recent months with uncharacteristic autopsies (abscess, arthritis, opportunistic germs) and several fever strikes last fall. The cows had received, without success, anti-inflammatories and/or antibiotics. And this spring, it starts again. A little after the putting out to grassin one week, seven cows suddenly started to eat less, dropped by half their milk production and presented a high feversometimes more than 40°C.
The affected cows did not no specific symptoms : no cough, nasal discharge, diarrhea, mastitis, arched back or lesions in the mouth. Only high fever, loss of appetite and milk. The calves are doing well. There reproduction is going pretty well. There ration seems adequate. THE rate and production are good. THE results BVD on the loops do not show circulation of the virus. THE parasite analyzes at the start of winter were good. Research Ehrlichiosis had been made two years ago during a less violent episode and were negative.
Several samples are carried out: trace element assessment, besnoitiosis serology on autumn patients, PCR ehrlichiose on feverish patients of the week and search for RSV (respiratory virus) on a respiratory sample. The result is clear: 100% positive for ehrlichiosis, everything else is within the norms.
Things to remember
L’ehrlichiose
• Transmitted by ticks
• Cause high fever, drop in production and appetite, drop in immune defenses, possibly edema of the pasterns
• Can be limited with an antibiotic, but you must focus on the prevention and management of ticks
• Can affect humans
Little beast, big consequences
L’Ehrlichiosis is a disease due to a bacterium, Anaplasma phagocytophylumwhich lives and multiplies in white blood cells. It is transmitted by a tick, Ixodes ricinuspresent everywhere in France except in the Mediterranean basin and to a limited extent above 1,000-1,200 m altitude. The bacteria can be transmitted to cattle, small wild or domestic ruminants, dogs, horses, foxes and humans.
The symptoms are not always obvious: they are sometimes absent, but there is often a high fever (above 40°C) and a sometimes lasting drop in milk production. The presence of a edema in the pasterns of the hindquarters is rare but very characteristic. There may also be pneumoniaof the abortionsa drop in immune defenses and greater susceptibility to other diseases (Q fever, mammites…).
The disease often reappears in spring, when it is put out to pasture, and more often on young people or purchased animals. Wildlife possibly plays a role, particularly in the spread of ticks. The diagnostic de certitude is done thanks to a blood test with search for bacteria or antibodies depending on the duration of the disease. The antibiotic oxytetracycline normally helps improve the condition of patients, but the results are not always up to par. Anti-inflammatories help reduce the fever a little but do not limit theinfection in itself.
The means of prevention are a little complicated to set up but essential:
• Pasture management for limit contact between cattle and ticks : clearing, trimming hedges (where ticks live), moving fences back one meter from hedges.
• External antiparasitics : there are many fly repellents, but deltamethrin is used in higher doses for ticks than for flies, and this systematically leads to a milk withdrawal period. The duration of action also remains limited to 4-6 weeks. It is therefore difficult to treat all animals systematically during the grazing season. Natural antiparasitics have a more limited persistence over time.
• Allow young heifers to become contaminated: young people often have fewer clinical signs than adults, but relapses in adulthood remain possible.
• None vaccine does not exist at the moment.
Tick management, a real challenge
Ticks can transmit several diseases: erhlichiosis, the more classic and well-known piroplasmosis, but also Lyme disease, anaplasmosis, etc. Unreasonable use of antiparasitics will lead to in fine resistance, it is therefore on grazing management that we must concentrate and on immunity. Note that if cattle regularly carry ticks, the breeder must pay attention to their own health. A red halo that appears on a tick bite, sometimes several centimeters in diameter, an episode of fever or migraine after a bite, should not be taken lightly and requires a visit to your doctor.
