This organism is a rickettsia, half-way between a virus and a bacteria. It is susceptible to tetracyclines. The organism is an obligate parasite, which means it cannot be grown in the laboratory. The disease is caused when infected cattle react to the organism, and their body removes its own infected red blood cells. This causes a severe anemia.
All cattle are susceptible to infection by A. marginale.
Recently, you may have attempted to purchase vaccines to prevent anaplasmosis and discovered they are no longer available. Since the first of the year, the two U.S. companies that manufactured and marketed vaccines for the prevention of anaplasmosis nationwide have decided not to continue making these vaccines. The first anaplasmosis vaccine manufactured for cattle in the United States was made by Fort Dodge and was called Anaplaz . Both of these vaccines protect against anaplasmosis by similar mechanisms. The vaccines contain the organism, Anaplasma marginale, which is harvested from infected cattle.