Many Oklahoma beef producers associate anaplasmosis with horse flies, and keep up a prevention program only during the fly season. Unfortunately, many of these same producers are still experiencing anaplasmosis problems year around, because biting flies are only a minor vector compared to other ways the disease can be transferred. In many areas, especially wooded or brushy pastures, ticks are more important vectors than biting flies. Ticks are an all-year problem in many areas of Oklahoma, so the control program also needs to be maintained all year. Stockmen also spread the disease from carriers to susceptible animals by not removing all traces of blood from equipment when processing adult cattle. The organism can be carried by needles, dehorners, castration knives, ear taggers, or any other implement that draws blood. It is sometimes possible to determine the source of the outbreak by the way cases develop. When insect vectors are responsible there will usually be one sick animal, followed several weeks later by multiple cases. If human transfer is the cause, several sick animals will show up at the same time 2 to 4 weeks after the cattle were worked.
The most popular means of anaplasmosis prevention is the use of mineral mixes that contain chlortetracycline (CTC). When fed at a rate of 0.5 mg/lb. of body weight CTC will prevent anaplasmosis infections. It is important to note, however, that CTC is added to minerals for several different reasons, including use as a growth promotant for yearlings, and these other uses require different levels of drug in the mineral. Make sure that the product you choose states on the label that it is formulated at a rate for the prevention of anaplasmosis, and gives the specific amount of daily consumption needed to supply that level. The next step is to monitor your herd to make sure that the product is being consumed at the appropriate rate. If not, you may need to look at other products or change your management practices in order to correct consumption deficits. It is very possible to have a few cases even when medicated minerals are provided, because some individuals may not consume them. For problem herds or as an alternative preventative, a killed vaccine is available in selected states including Oklahoma. It may be especially valuable for use in bulls, who often do not consume enough mineral to meet the CTC requirement for their body weight. Another control factor is the elimination of carriers. Recovered animals will be carriers of the disease and a source of infection for susceptible individuals. Clear them of the organism with high levels of antibiotics administered parentally, isolate them from susceptible animals, or cull them from the herd.