Anaplasmosis in Cattle

Anaplasma marginale

Location and host

• Cattle are main host but infection also occurs in RBC of water buffalo, bison, African antelopes, Zebra, deer, mule, camel. Vector of this parasite are different species of tick ; Boophilus, Derma center, Hyalomma, Ixodes, Rhipicephalous but stable flies, tabonids and mosquitoes also transmit the disease.

Morphology

• A. marginale occur as round, filamentous, oval or disc like
• They are found near the margin of erythrocytes
• Size of parasite is 0.2-0.5µm in diameter.
• Only one organism is found in one red cell.
• In Giemsa-stained blood films, they are seen as round, small, dark red ‘inclusion bodies’  within red cells.

Life cycle : same as above.

Transmission

• Primary mode of transmission is through ixodid tick of genus Boophilus, Derma center, Hyalomma, Ixodes and Rhipicephalous.
• Argas and Ornithodorous also acts as vector.
• Mechanical transmission may occur through blood sucking flies; tabonid flies, stomoxys and mosquitoes.
• They can also be transmitted during surgical operations like dehorning, castration, vaccination , blood sampling, etc.

Clinical signs

• Incubation period is 15-36 days.
• Fever which fluctuates with irregular periods.
• Anorexia
• Pale/Jaundice mucous membrane
• Hemoglobinuria is absent
• In per acute cases, there is sudden onset of fever, anemia, icterus, severe dyspnea and death within 24 hours.
• In chronic case, there is severe anemia. Animal becomes susceptible to their infections.
• Loss of milk production in cows
• Abortion in pregnant cows.

Diagnosis

• Based on clinical signs and symptoms.
• Detection of organism in blood smears.
• Detection of organism by serological test to complete fixation, capillary tube agglutination, gel precipitation and fluorescent Ab tests.

Treatment

• Tetracycline @ 6-10 mg/kg body weight, single dose intramuscular (effective).
• Imidocarb and berenil are also used.
• Support and treatment include slow administration of blood transfusion.

Prevention and control

• Control of ticks: Dipping of animal on ectroparasiticidal solution helps in control of tick.
• Proper treatment of positive cases in segregation helps in effective control of disease.

A . centrale

Introduction

• These organisms are less pathogenic. All are same as marginale but they are commonly found in center of erythrocytes.
• Others same as above