Anaplasmosis is a disease that can strike fear in beef producers. There have been cases reported and confirmed in various parts of Ohio this year and it is an issue that needs to be addressed, says William Shulaw OSU Extension veterinarian. He says the disease does not usually get a lot of attention in Ohio.
"I have gotten calls about it about every 2-3 years since I began working in veterinary Extension in 1988," Shulaw says. "One of my colleagues indicated to me several years ago that he had diagnosed it in at least one Ohio herd as far back as the mid-1970s. We know very little about the prevalence or natural history of the disease in this state, however, it occurs in many states in the southeastern US, the Gulf Coast states, and some regions of the West."
Anaplasmosis is a disease affecting the red blood cells of cattle and is caused by a rickettsial parasite called Anaplasma marginale. Parasitized red blood cells are removed from the circulation and destroyed by the spleen and liver. When high levels of parasitized cells occur, usually shortly after a cow is first infected, severe anemia can result; sometimes resulting in deaths or abortions. If a cow recovers from the infection, she becomes a carrier of the disease for the rest of her life. Calves that become infected before about a year of age seldom show much in the way of clinical signs except for perhaps a fever lasting just a few days. They too become carriers for life.
The disease can be mechanically transmitted by biting flies and blood-contaminated inanimate objects such as hypodermic needles, some tagging instruments, surgical instruments, nose tongs, and possibly tattoo equipment. Fortunately, the organisms in a drop of blood don't survive on insect mouth parts or equipment for very long and cleaning and disinfection of equipment reliably destroys them. There is recent evidence that contaminated injection equipment may be a more reliable way to spread the disease than we once thought. Certain species of ticks can also spread the disease, and the male tick in some of those species is now thought to be most important because it can become a persistent carrier in which the organism actually multiplies. Ticks do not appear to be important transmitters of the disease in some areas. The incubation period from exposure to clinical signs varies from about 10-60 days.