Human granulocytic anaplasmosis A28.8

Human granulocytic anaplasmosis (older name: human granulocytic ehrlichiosis) is an infection transmitted by ticks (especially Ixodes ricinus), which is caused by the gram-negative bacterium Anaplasma phagocytophilum (multipliesobligatory intracellularly in granulocytes).

In Europe, few diseases have become known due to the high proportion of asymptomatic infections. Case reports from the USA, Austria, Slovenia, Portugal, Belgium and Italy are available (Hing M et al. 2018).

65 to 75% of all infections are asymptomatic. After an incubation period of about 5 to 30 days, the following flu-like symptoms may occur: high fever, severe headache, malaise, nausea, vomiting, diarrhoea, muscle pain, joint pain. Less frequent are unspecific exanthema. Risk of pneumonia in immunocompromised patients.

Increase in transaminases, leukocytopenia with lympho- and neutropenia, thrombopenia. C-reactive protein (CRP) and BSG increased, possible increase in CK. Detection of antibodies; titers remain high for a long time after infection.

Clinic with tick bite history, serology (IgG-Ak: 4-fold increase in titer between 1st and 2nd sample (after 2-4 weeks).

Note: often simultaneously false positive Borrelia serology due to cross-reaction!

HGA-DNA from blood (PCR)

Blood and bone marrow smear: detection of intrcytoplasmic inclusion bodies in granulocytes (morulae)

Medium of choice: Doxycycline (2x100mg/p.o. over 14 days). Alternative: Rifampicin.

In view of the wide distribution of the bacterium in European ticks, a much larger number of infections can be assumed, which probably remain mostly undetected due to the lack of knowledge about the pathogen. As a result of cross-reactions, Borrelia serology can be positive.

1. Bakken JS et al (2015) Human granulocytic anaplasmosis. Infect Dis Clin North Am 29: 341-55.

2. Hing M et al. (2018) Prevalence of Anaplasma phagocytophilum in humans in Belgium for the period 2013-2016. Acta Clin Belg 20:1-6.