Clinical and laboratory features parameters of human granulocytic anaplasmosis (HGA) in patients admitted to hospital in Guangdong Province, China

Background Human granulocytic anaplasmosis (HGA) is an acute tick-borne infectious disease with increasing morbidity and mortality, but is rarely considered in clinical practice. Because human-to-human transfusion or nosocomial transmission can occur, diagnosis is difficult when the history of tick bites is not clear. Methods We present clinical features and laboratory data of HGA patients who had no clear tick bite history. Results All patients in the study presented with a high fever, petechiae, purpura, nose bleeding and leukopenia, and patients had abnormally high levels of serum ferritin and C-reactive protein. Morulae in leukocytes were observed in three patients. Foamy histiocytes and slight erythrophagocytic activity were only found in severely ill patients. Conclusion In patients with fever and thrombocytopenia in whom no other diagnosis is evident on clinical assessment, HGA should be considered in the differential diagnosis, and tested for serologically if possible. For patients in whom the diagnosis of HGA is possible, and to whom tetracyclines can safely be given, it is apparent that these drugs hasten recovery and improve the prognosis.