Anaplasmosis: Old Disease, New Problem

August 2000
Jim Selph - DeSoto County Extension, Director/Livestock Agent

Anaplasmosis is an infectious disease of cattle caused by a parasite, Anaplasma marginale, that is found in the red blood cells of infected cattle. Although most cattle in South Central Florida are infected by this disease, problems have been few because most become infected at a young age. When calves become infected under six months of age, they will very seldom show enough symptoms to detect that they have been infected. From 6-months to 3 years of age, cattle become increasingly ill with infection and if infected after 3 years, up to percent will die if left untreated.

At this point, one has to ask, "What is the New Problem?" The answer to that is simple, we lost the vaccines in 1998 that for years we had used to vaccinate 2 and 3 year old bulls that were brought into Florida from areas that were basically free of this disease. The consequence of this is that these older bulls are at a much higher risk of contracting the disease and possibly dying or not being available at the critical time of breeding. When bulls average $1,500 to $2,000 for a commercial bull, several losses could spell economic problems even in the current market cycle.

Since we currently do not have a vaccine available, then it becomes very important for cattlemen to recognize the clinical signs of Anaplasmosis. If infected you will first notice an anemic animal (pale skin around the eyes, on the muzzle, on the lips, inside the mouth, and the teats) that will be weak and lag behind the herd (especially when working and moving cattle). Other signs can be constipation, rapid weight loss, excitement and yellow-tinged skin. Often a cow/bull will fall or lie down and be unable to get up. Cattle that survive the clinical disease will recover slowly over a two or three month period. Again, keep in mind the susceptible bull, that might become infected at the beginning of the breeding season. Once infected, they become carriers and will rarely show clinical signs a second time.

Also important for the cattleman to know is how the disease moves from an infected animal to a susceptible one. The transmission is considered to be mechanical: either by the mouth parts of biting/sucking insects or by contaminated instruments used by man. Horse flies, deer flies, stable flies, mosquitoes and ticks are known to transmit infected red blood cells from the diseased animal to the susceptible one. Cattlemen using dehorning saws, castrating knives, needles, tattoo instruments or any bladed instrument that have not been disinfected can transmit the disease.

Well, what do we do this year especially with bulls or heifers purchased from out of state? Currently, there is no vaccine available. However, I am informed that cattlemen can have their local veterinarian purchase an experimental vaccine (version of the old vaccines) from Louisiana. Also bulls can be brought in every 28 days and be given a shot of Oxytetracycline as a preventive treatment. There is hope that a new vaccine will be developed in the next year or two. Oklahoma State University has reported a major breakthrough in producing a new vaccine. As of yet, that vaccine does not include an islet of the strain that causes the infection in Florida. It is reported that Grand Laboratories will market this new vaccine.

I have written this article because of the need for cattlemen to know and understand the status of this disease and with the hope that this article might stir some major discussion on Cattletalk. Give it some thought.

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