Anaplasmosis

Figure 1. Schematic of a blood smear from a cow infected with Anaplasma marginale (dark spots on the edge of the red blood cells). Image courtesy of the Tick Fever Centre
Figure 1. Schematic of a blood smear from a cow infected with Anaplasma marginale (dark spots on the edge of the red blood cells). Image courtesy of the Tick Fever Centre

Anaplasmosis is caused by the organism Anaplasma marginale (Figure 1). It is transmitted by the cattle tick and is thought to be transferred mainly by direct movement of male ticks from carrier animals to other animals when they are in close contact. The course of the disease is more gradual than that associated with babesiosis, and the animals may be quite anaemic and jaundiced by the time clinical illness is noted.

Signs

The main clinical signs are pale and/or yellow mucous membranes (anaemia and/or jaundice); note that the urine does not turn red with anaplasmosis but may appear as a dark brown colour. Other clinical signs of anaplasmosis may include fever, loss of appetite, lethargy and depression, weakness and loss of condition.

Diagnosis

As with babesiosis, many of these clinical signs are non-specific and can be associated with other conditions, so it is important to confirm the diagnosis by examination of blood smears under a microscope.

Treatment and control

See these pages for the treatment and control of tick fever.