Anaplasmosis in Wisconsin Cattle

Anaplasmosis is a bacterial organism that infects red blood cells of cattle. This pathogen parasitizes red blood cells to survive, and as the infection progresses, the animal eventually becomes anemic. The loss of red blood cells leads to a decreased oxygen-carrying ability, which then leads to clinical signs. Many times, the first clinical sign of the disease is dead adult cows or bulls found in the pasture.

The older the animal is when first infected, the more severe the clinical signs are. High fever is the first inflammatory response that develops when the older animal becomes infected. Red blood cells are destroyed as the immune system kills the bacteria. 

The animal develops ane-mia and oxygen carrying capacity declines as the red blood cells decrease; the animal’s heart rate and respiratory rate increases, and the animal becomes exercise intolerant. Production suffers as the animal weakens. Fatalities may occur in cattle who are over two years of age when first infected. 

Youngstock that are less than one year of age when first infected may develop a mild case of anaplasmosis and then appear to get better, but they are infected for life. Carriers rarely become ill with anaplasmosis a second time and it’s the unidentified carriers that serve as the source of infection for the herd.

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