Human Granulocytic Anaplasmosis

Abstract

SynopsisHuman granulocytic anaplasmosis (HGA), a deer tick transmitted rickettsial infection caused by Anaplasma phagocytophilum, is a common cause of undifferentiated fever in the Northeast and Upper Midwest U.S. Patients are often initially diagnosed with a mild viral infection, and illness readily resolves in most cases. However, as many as 3% may develop life threatening complications and nearly 1% die from the infection. A history of tick bite and a high degree of clinical suspicion thus warrant consideration for doxycycline treatment in both adults and children, even in the absence of known tick bite, a negative blood film examination, or pending results of specific A. phagocytophilum diagnostic tests such as paired serology or PCR on acute phase blood. Antibody tests and titers should not be used to monitor active infection as detectable antibodies can remain present for years. Moreover, persistent infection has never been reported. While coinfections with Borrelia burgdorferi and Babesia microti occur, there is little evidence to suggest synergism of disease or a role for A. phagocytophilum in chronic illness. Preventive measures include avoiding tick-infested areas, use of tick repellents, and careful searches of skin to remove attached ticks; no vaccine is available.

Update on tick-borne bacterial diseases in Europe

“…Complete removal of attached ticks is indicated with tweezers or forceps close to the skin. Routine disinfection of the bite wound is recommended to avoid contamination of the bite site with skin bacteria (Bakken & Dumler, 2008;Aberer, 2009). European clinicians should be aware of the clinical signs of tick-transmitted diseases in patients with unexplained febrile illnesses, and a careful travel and tick exposure history should be taken.…”

“…It is not transmitted transovarially in ticks; small mammals, particularly Apodemus sylvaticus (wood mouse), A. flavicollis (yellownecked mouse), Sorex araneus (common shrew) and especially Clethrionomys glareolus (bank vole), have been implicated as HGA reservoirs in Europe. A limited number of laboratory-confirmed HGA cases have been reported in Austria, Italy, Latvia, the Netherlands, Norway, Poland, Slovenia, Spain, France, Russia and Sweden, (Bakken & Dumler, 2008;Parola, 2004;Lotric-Furlan et al, 2006). Serologic studies also support the presence of HGA infection, much of which may be asymptomatic, in potentially exposed adults in Germany, Bulgaria, Denmark, Spain, Italy, Estonia, Greece, and France (Parola, 2004).…”

“…The first patient to have recognized HGA was reported in the U.S. in 1990; the first European case was reported in Slovenia in 1997 (Petrovec et al, 1997). By the end of December 2004, at least 2,871 cases of HGA were reported from 13 U.S. states to the Centers for Disease Control and Prevention (CDC) (Bakken & Dumler, 2008). In 2002, Blanco and Oteo (Blanco & Oteo, 2002) compared the clinical and laboratory features of 15 European patients to those reported for U.S. patients.…”

Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis — United States

“…Severe anaplasmosis can also resemble toxic shock syndrome, TTP (164), or hemophagocytic syndromes (165). Serious and fatal opportunistic viral and fungal infections during the course of anaplasmosis infection have been described (166,167). Although the case-fatality rate among patients who seek health care for anaplasmosis is <1%, approximately 7% of hospitalized patients require admission to the intensive care unit (13,166,168).…”

Autophagosomes induced by a bacterial Beclin 1 binding protein facilitate obligatory intracellular infection

“…Ap infects granulocytes and endothelial cells of various mammalian species (9). In humans, Ap causes an emerging and major tick-borne disease called human granulocytic anaplasmosis, an acute febrile disease that is potentially fatal, especially in elderly or immunocompromised individuals (10). Ap replicates inside the membrane-bound vacuole (inclusion) that is secluded from the endosome-lysosome pathway (11).…”