A Member of the University of Maryland Medical System | In Partnership with the University of Maryland School of Medicine
Babesiosis; Human granulocytic anaplasmosis (HGA)
Since 1991, when Lyme disease became a reportable disease, annual cases have doubled. (This increase is probably both due to increased infection rates as well as better diagnosis.) In general, about 25,000 cases of Lyme disease are now reported in the U.S. each year.
Anyone exposed to ticks is at risk for Lyme disease and other tick-borne diseases. Pets are also at risk. Naturally, anyone who is regularly outside in areas where tick rates are high has a greater than average risk for becoming infected.
Age. The highest reported incidence of Lyme disease occurs among children 5 - 14 years old and adults 45 - 54 years old.
Sex. Men and women are equally at risk.
In general, the risk for developing Lyme disease after a tick bite is only 1 - 3%. The risk varies depending on different factors:
Locations in the U.S. Lyme disease has been reported in nearly all U.S. states. However, most Lyme disease cases are concentrated in the northeastern, mid-Atlantic, and north central states. Although Lyme disease was named for a town in Connecticut where the first American cases of the disease were described, in recent years Massachusetts, New Jersey, and Pennsylvania have reported the greatest number of cases.
Worldwide Locations. Pockets of Lyme disease exist around the world. The disease is common in Europe, particularly in forested areas of middle Europe and Scandinavia. The Borrelia family is also responsible for tick infections in Europe, but different subspecies (B. garinii and B. afzelii) may be more common there and cause slightly different symptoms. The infection has also been reported in Russia, China, and Japan.
Deer ticks thrive in grassy areas that have low sunlight and high humidity. Woodlands and fields are prime habitats, but these ticks can also be found in the long grasses adjacent to beaches. The ticks are not confined to rural settings. In suburban areas, they can live in overgrown lawns, groundcover plants, and leaf litter.
The exact time of year for risk depends on a geographic region's seasons and how they affect the tick's breeding cycle. In general, the highest risk for Lyme disease onset is from June through August, and the lowest risk is from December through March.
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.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).
© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885