The immune system will attempt to kill the infected blood cells but will also kill uninfected red blood cells in the process. The number of red blood cells being destroyed becomes larger than new red blood cells being made, causing the host to become anemic and leading to many other symptoms. Once infected with anaplasmosis, the cattle will always be a carrier of the infectious disease, and calves born from carriers will also carry the disease. Signs and symptoms
Classic signs and symptoms of anaplasmosis will not occur until 3–6 weeks after infection. The most common symptoms of anaplasmosis include fever, a decreased number of white blood cells, platelets in the bloodstream, and abnormally elevated levels of liver enzymes. The erythema chronicum migrans rash may be seen with anaplasmosis as it is co-transmitted in 10% of Lyme disease cases. Anemia may be severe and result in cardiovascular changes such as an increase in heart rate. Blood in the urine may occur due to the lysis of red blood cells. General systemic signs include diarrhea, anorexia, and weight loss. Infected animals may develop a jaundiced look which then turns into paleness around the eyes, muzzle, lips, and teats of the cattle.All cattle are susceptible to infection by Anaplasma marginale, but the severity worsens with age increase. Older cattle tend to exhibit the most severe clinical symptoms; cattle aged 1–3 may also show severe symptoms but are able to recover easier. Causes
The two major species that cause anaplasmosis in ruminants include Anaplasma marginale and Anaplasma phagocytophilum.
Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by Anaplasma bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector processes. Anaplasmosis can also be referred to as "yellow bag" or "yellow fever" because the infected animal can develop a jaundiced look. Other signs of infection include weight loss, diarrhea, paleness of the skin, aggressive behavior, and high fever.Many different tick species can carry the bacteria that cause anaplasmosis. The two major bacterial pathogens are Anaplasma marginale and Anaplasma phagocytophilum. These microorganisms  are Gram-negative, and infect red blood cells. Once the host is infected with anaplasmosis, the immune system will try to fight off and kill the infected red blood cells, but will also kill healthy red blood cells. The Anaplasma sparouinense species is responsible for a rare zoonosis, the Sparouine anaplasmosis, detected only in French Guiana, South America. This disease was described from a clandestine gold miner working deep in rainforest. Infection of his red blood cells led to a severe deterioration of his health and required his hospitalization. Molecular typing showed that Anaplasma sparouinense is distinct to all known species and more genetically related to recently described Anaplasma species causing infections in rainforest wild fauna of Brazil.While there are no current live or inactivated vaccines effective for all strains of A. marginale approved by the USDA for anaplasmosis, there are other means of prevention. Tick and fly control for herds of ruminants can be effective but also labor intensive.