Kingdom: Bacteria

Phylum: Proteobacteria

Order: Rickettsiales

Family: Anaplasmataceae

Anaplasmactaceae

• These are very small; ricketisia-like particles occurring in or on the erythrocytes of vertebrates.
• Transmitted by arthropods
• Four genera out of which Anaplasma, Ehrlichia and Aegyptianella are important pathogens.

Genus: Anaplasma

• Species of this genus occur in red blood cells of cattle, sheep, goats and related species of animals.
• Blood smears stained with commanocusky stain, shows deep-red-colored organism inside red cells. Measure 0.2-0.5 µm in diameter with no cytoplasm and with light halo around them.
• 3 Species of the genus are responsible for anaplasmosis in farm animals. There are marginale and A. centrale in cattle and A. ovis in sheep and goat.

Note: Invagination: Action or process of being turned inside out or folded back on itself to form cavity or pouch.

Life cycle  (A. marginale)

• Anaplasma are obligate intracellular parasite infecting granulocytes mostly neutrophils.
• Animal gets infection after tick flies bites susceptible host.
• Once released in blood, organisms enter RBCs by invaginating cell membranes and vacuoles is formed.
• After invading RBCs, they divide to form inclusion bodies containing upto 8 initial bodies packed together (morulae).
• Ticks gets infection when they feed on host and part of cycle occurs inside ticks. They are transmitted trans-staidly. These parasites multiply inside gut of tick cell. First there is vegetative form which gets developed into dense form (infective form).
• After multiplication, they leave gut cells and reaches to salivary gland of tick simultaneously when moulting occurs in tick. Animal gets infection after these ticks feed on new susceptible host.
• Vector tick are Boophilus, Derma center, Hyalomma, Ixodes and Rhipicephalous.