Anaplasmosis

Anaplasmosis is a type of tick fever that is caused by invasion of red blood cells by the rickettsial blood parasite

Disease Details

Introduction: Anaplasmosis, also known as gall sickness, is a vector-borne, infectious blood disease of ruminants caused by rickesttsial parasites. It is also known as yellow-bag or yellow-fever. It occurs mainly in warm tropical and subtropical areas.  Bovine anaplasmosis is of economic significance in the cattle industry.

 Causes: Anaplasmosis in cattle caused by the Anaplasma marginale and Anaplasma centrale. A ovis may cause mild to severe disease in sheep, deer, and goats. The intracellular parasite destroys red blood cells and causes severe anemia.

 Transmission: The disease is not contagious but it is most usually spread by ticks. More than 17 different tick vector species (including Ixodes, Hyalomma, Argas) have been reported to transmit Anaplasma spp. It can also be transmitted via contaminated utensils, biting flies and mosquitoes. 

 Symptoms: Major clinical symptoms are Anemia, Fever, Weight loss, Breathlessness, Jaundice, Uncoordinated movements, Abortion and Death. The disease is generally mild in calves under a year of age, rarely fatal in cattle up to two years of age, sometimes fatal in animals up to three years of age, and often fatal in older cattle.

 Lesions: Lesions are typical of those found in animals with anemia due to erythrophagocytosis. The carcasses of cattle that die from anaplasmosis are generally markedly anemic and jaundiced. Blood is thin and watery. The gallbladder is often distended and contains thick brown or green bile. Hepatic and mediastinal lymph nodes appear brown. A significant proportion of erythrocytes are usually found to be parasitized after death due to acute infection.

 Diagnosis: Diagnosis is based on clinical signs and the examination of blood under microscope for evidence of the parasite. 

Treatment: Tetracycline is often used for clinical anaplasmosis. General supportive care is also important for anemic animals. The incubation time for the disease to develop varies from two weeks to over three months, but averages three to four weeks. Adult cattle are more susceptible to infection than calves. 

 Prevention: Therefore, control of vectors is key to preventing anaplasmosis. If necessary herd treatment with oxytetracycline injection every 3 to 4 weeks during high risk times may be necessary will prevent clinical disease but animals can become carriers. Chlortetracycline also known as CTC can reduce the risk of anaplasmosis. In some places, vaccines are available to increase resistance to anaplasmosis.