Anaplasma phagocytophilum

Human Granulocytotropic Anaplasmosis (HGA)

Anaplasma phagocytophilum (Human Granulocytic Anapasmosis)

o Intracellular pathogen in granulocytes

o Synergistically suppresses host immune system with Bb infection

In addition to Lyme disease, ticks can carry many other infections. Human granulocytic anaplasmosis (HGA- formerly called human granulocytic ehrlichiosis) is one of the infections. The HGA bacteria infects white blood cells.

SYMPTOMS- HGA symptoms usually appear within a few days to two weeks after being bitten by an infected tick. Symptoms include severe headaches, fever, chills and shaking, loss of appetite, joint aches and muscle pain. The patient may experience vomiting, diarrhea, cough or a loss of appetite. A rash may appear in a small percentage of patients. Symptoms of HGA may be very mild to quite severe.

DIAGNOSIS- Blood tests for Anaplasma may be negative, especially in the acute phase. Routine blood tests may indicate a low blood platelet count, low white blood cell count or increased liver enzymes.

TREATMENT- Adult patients who show signs or symptoms of HGA should immediately be treated with an antibiotic (doxycycline is drug of choice) to reduce the risk of severity and long term complications. Rifampin is an option for pregnant women, children younger than 8 years of age, or patients who are allergic to doxycycline.


More Information on HGA (Pg. 1828 CDC)

"What is unclear from these data is whether the discrepancy between the seroprevalence and symptomatic rate results from underdiagnosis of infection, asymptomatic serologic reactions, or even infections that produce cross- reactive serologic responses. In any case, symptomatic infection can occur often in tick-endemic regions and varies in severity from mild, self-limited fever to death.

Severity sufficient for hospitalization is observed in half of symptomatic patients and is associated with older age, higher neutrophil counts, lower lymphocyte counts, anemia, the presence of morulae in leukocytes, or underlying immune suppression (5). Approximately 5%–7% of patients require intensive care, and at least 7 deaths have been identified (2,4,5,7,19), in which delayed diagnosis and treatment were risk factors.

Severe complications include a septic or toxic shock–like syndrome, coagulopathy, atypical pneumonitis/acute respiratory distress syndrome (ARDS), acute abdominal syndrome, rhabdomyolysis, myocarditis, acute renal failure, hemorrhage, brachial plexopathy, demyelinating polyneuropathy, cranial nerve palsies, and opportunistic infections. At least 3 of the deaths resulted from opportunistic fungal or viral infections or hemorrhage that occurred immediately after HGA."