Also known as: Lyme borreliosis and Tickborne meningopolyneuritis
Hospital: Report by IDSS, mail, fax or phone
Infection Perventionist: Report by IDSS, mail, fax or phone
Lab: Report by IDSS, mail, fax or phone
Physician: Report by mail, fax or phone
Local Public Health Agency (LPHA): Follow-up required
Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698
Lyme disease (LD) is caused by the corkscrew-shaped bacterium (spirochete) Borrelia burgdorferi.
B. Clinical Description
Lyme disease is a systemic, tick-borne disease with a variety of manifestations, including dermatologic, rheumatologic, neurologic, and cardiac abnormalities. The best clinical marker for the disease is erythema migrans (EM), the initial skin lesion that occurs in 60%-80% of patients.
EM is a skin lesion that typically begins as a red macule or papule and expands over a period of days to weeks to form a large round lesion, often with partial central clearing. Secondary lesions also may occur. Round erythematious lesions occurring within several hours of a tick bite represent hypersensitivity reactions and do not qualify as EM. For most patients, the expanding EM lesion is accompanied by other acute symptoms, particularly fatigue, fever, headache, mildly stiff neck, arthralgia, or myalgia. These symptoms are typically intermittent. Laboratory confirmation is recommended for persons with no known exposure.
Signs and symptoms during the early illness tend to be nonspecific and include fever, muscle aches, headache, mild neck stiffness, and joint pain. Erythema migrans (EM) occurs at the site of the tick bite in approximately 90% of cases, although when these painless lesions occur in a location hidden from view (armpit, back, etc.), the patient does not often see them. Typically, EM rashes are circular and grow to a diameter of 5 to 15 cm, although the shape can be triangular, oval, or irregular. EM frequently clears in the center, resulting in the classic “bull’s-eye” presentation, but this does not always occur. The rash may be reported as warm or itchy, but it is usually painless.
In untreated persons, multiple EM rashes may appear within 3 to 5 weeks after the tick bite. These secondary lesions, indicative that the infection has spread into the blood, resemble the primary lesion but tend to be smaller. Common signs of early disseminated disease also include mild eye infections and the paralysis of facial muscles (Bell’s palsy). More systemic signs of this stage are headache, fatigue, and muscle and joint pain. At this stage, disruptions of heart rhythm occur in < 10% of cases.
Most commonly, late disease is marked by recurrent arthritis (swelling and pain) in the knees and shoulders. Other joints may also be involved. Neurological signs may involve impairment of mood, sleep, or memory; paralysis of facial muscles; pain or tingling sensations in the extremities; and less commonly, meningitis and encephalitis. Late-stage symptoms can persist for several years, but tend to resolve spontaneously.
Generally, prophylactic antibiotic therapy is not indicated after a tick bite, as the risk of infection with B. burgdorferi after a tick bite is relatively low, even in endemic areas.
The primary vectors for Lyme Disease (LD) are Ixodes ticks, a distinct genus from the larger and better-known dog tick (Dermacentor variabilis). In Iowa, the prominent vector is I. scapularis, or the deer tick. Ticks acquire the spirochete that causes LD during their young, larval stage by feeding on infected animals, especially the white-footed mouse. The tick poses the greatest threat of transmitting infectious organisms to animals and humans when it bites during its next (nymphal) stage of life. Nymphs are most abundant between May and July, and they are typically found in grasses and brush. Towards the end of summer through fall, the ticks mature to the adult stage. Although adult ticks remain capable of transmitting B. burgdorferi to humans, they are less likely to do so.
D. Modes of Transmission
Lyme disease is acquired from a tick bite. Laboratory data suggest that the tick must usually remain attached for 24 to 48 hours before the transmission of B. burgdorferi can occur. Since bites from I. scapularis are often painless and may occur on parts of the body that are difficult to observe, cases of diagnosed LD frequently have no known history of a tick bite.
E. Incubation period
EM typically develops between 7 - 10 days after exposure (range 3 - 32 days). However, an infected individual can remain asymptomatic until the later stages of LD, several months to one year later.
F. Period of Communicability or Infectious Period
Lyme disease is not communicable from person-to-person.
Lyme disease is the most commonly reported vectorborne illness in the U.S. In 2009, it was the 5th most common nationally notifiable disease. In 2010, 94% of Lyme disease cases were reported from 12 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New Hampshire, New York, Pennsylvania, Virginia, and Wisconsin.
The incidence of Lyme disease is associated with the density of infected tick vectors. While most cases in the United States have been reported in the Northeast, West, and upper Midwest, nearly all states have reported cases. LD incidence varies greatly among states, among counties, and by season. Most cases occur between April and October, when the risk of contact with nymphal ticks is greatest. In Iowa most cases occur in the northeast corner of the state.
H. Bioterrorism Potential
I. Additional Information
If a tick is available it may be sent for testing. Place tick in plastic bag, with a tissue and one to two drops of water, seal, place in envelope with your name, address, and phone number and mail to:
Iowa State University
Department of Entomology
440 Science II
Ames, IA 50011-3240
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for Lyme Disease can be found at: www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm#top
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2009 Red Book: Report of the Committee on Infectious Diseases, 28th Edition. Illinois, American Academy of Pediatrics, 2009.
American Lyme Disease Foundation, Inc. A Quick Guide to Lyme Disease: How to Protect Yourself and Your Family from Serious Infection. (Not dated.)
Heymann, D., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.
Centers for Disease Control and Prevention. www.cdc.gov/lyme/
CDC Notice to Readers Recommendations for Test Performance and Interpretation from the Second National Conference on Serologic Diagnosis of Lyme Disease, MMWR August 11, 1995 / 44(31);590-591