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Lyme disease and related tick-borne infections - Human Granulocytic Anaplasmosis (HGA)

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of Lyme disease.

Alternative Names

Babesiosis; Human granulocytic anaplasmosis (HGA)

Human Granulocytic Anaplasmosis (HGA):

In addition to Lyme disease, I. scapularis deer ticks can carry other types of infections that cause disease in humans. Human granulocytic anaplasmosis (HGA) is another illness spread by the deer tick. (HGA was formerly called human granulocytic ehrlichiosis. Another type of ehrlichiosis, human monocytic ehrlichiosis, is carried by a different type of tick.)

Typical HGA symptoms appear very suddenly within 4 - 14 days of being bitten by an infected tick. Symptoms include headache, fever, chills, headache, and muscle pains. Vomiting, diarrhea, and loss of appetite are also common. Blood tests may indicate a low blood platelet count, low white blood cell count, and increased liver enzyme levels.

HGA is caused by a species of bacteria called Anaplasma phagocytophilum. A blood test can identify the presence of this bacterium.

All patients who show signs of symptoms should be treated with doxycycline to reduce the risk of complications. Another type of antibiotic, rifampin, is an alternative option for pregnant women, children younger than 8 years of age, or patients who are allergic to doxycycline. Treatment is not recommended for people who do not exhibit symptoms, even if they test positive for antibodies to A. phagocytophilum.

Resources

www3.niaid.nih.gov -- National Institute of Allergy and Infectious Disease
www.cdc.gov/ncidod/dvbid/lyme -- Centers for Disease Control
www.idsociety.org -- Infectious Diseases Society of America
www.aldf.com -- American Lyme Disease Foundation
www.rheumatology.org -- American College of Rheumatology
www.arthritis.org -- The Arthritis Foundation

References

Bakken JS, Dumler S. Human granulocytic anaplasmosis. Infect Dis Clin North Am. 2008 Sep;22(3):433-48, viii.

Bratton RL, Whiteside JW, Hovan MJ, Engle RL, Edwards FD. Diagnosis and treatment of Lyme disease. Mayo Clin Proc. 2008 May;83(5):566-71.

Centers for Disease Control and Prevention. Lyme disease -- United States, 2003-2005. MMWR Morb Mortal Wkly Rep. 2007 Jun 15;56(23):573-6.

Clark RP, Hu LT. Prevention of lyme disease and other tick-borne infections. Infect Dis Clin North Am. 2008 Sep;22(3):381-96, vii.

Feder HM Jr, Johnson BJ, O'Connell S, Shapiro ED, Steere AC, Wormser GP; Ad Hoc International Lyme Disease Group. A critical appraisal of "chronic Lyme disease." N Engl J Med. 2007 Oct 4;357(14):1422-30.

Halperin JJ, Shapiro ED, Logigian E, Belman AL, Dotevall L, Wormser GP, et al. Practice parameter: treatment of nervous system Lyme disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2007 Jul 3;69(1):91-102.

Vannier E, Gewurz BE, Krause PJ. Human babesiosis. Infect Dis Clin North Am. 2008 Sep;22(3):469-88, viii-ix.

Wormser GP, Dattwyler RJ, Shapiro ED, Halperin JJ, Steere AC, Klempner MS, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134.

Reviewed last on: 2/11/2009
Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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