an emerging tick-borne infectious disease
Anaplasma phagocytophilum, an intracellular, gram-negative aerobic bacterium, is the cause for granulocytic anaplasmosis in people, horses, dogs, cats, wolves, cattle and small ruminants. A. phagocytophilum mainly targets neutrophils and rarely eosinophilic granulocytes; in Europe it is transmitted by the tick Ixodes ricinus. A significant number of small mammals and deer comprise the reservoir for the microorganism in the wild. The majority of infected dogs remain asymptomatic, whereas those that develop clinical signs mostly present with non-specific signs like fever, depression or lethargy, anorexia and lameness. The most common laboratory finding of anaplasmosis is thrombocytopenia. Diagnosis is based on finding aggregates of the organism (morulae) in the cytoplasm of neutrophils, serological detection of specific antibodies and polymerase chain reaction. The treatment of choice is Doxycycline, administered per os at a dose of 5 mg/kg Β.W./12 hours for 2-4 weeks.