Lyme Disease

Home » Lyme Disease » Overview, Causes and Risk Factors, Signs and Symptoms, Diagnosis

Overview

Lyme disease is a progressive, systemic illness that is caused by bacteria (Borrelia burgdorferi) and is usually transmitted by the bite of an infected deer tick. Infection may result in flu-like symptoms (e.g., malaise, fever, headache, fatigue, muscle pain) and the characteristic "bull's eye" rash. If left untreated, it may cause arthritis and affect the heart and central nervous system. Lyme disease is treated with antibiotics.

Incidence and Prevalence
According to the Centers for Disease Control and Prevention (CDC), more than 23,000 cases of Lyme disease occur each year in the United States. It is endemic (prevalent) throughout the wooded coastal regions of the Northeast, the Great Lakes, and the Pacific Northwest. In the Northeast and Great Lakes regions, the disease is more prevalent from May to August. In the Pacific Northwest, it is more prevalent from January to May.

Causes and Risk Factors

Lyme disease is caused by infection with Borrelia burgdorferi bacteria. In the Northeast and North Central United States, the deer tick (Ioxodes scapularis) is responsible for transmission and in the Northwest, the western black-legged tick (Ioxodes pacificus) is the carrier.

The ticks that cause Lyme disease are very small. They live in wooded areas, low-growing grasslands near seashores, areas overgrown with brush, and in yards. The adult ticks are black or reddish and feed on blood by attaching themselves to a host.

The risk for contracting Lyme disease in the United States is highest in the coastal region of southern New England, the mid-Atlantic, and the Great Lakes. During the summer months, people who live or work outdoors (e.g., clearing brush, forestry, landscaping) in these areas are especially at risk. Ticks can also come into contact with people when they attach themselves to pets.

Outdoor activities that increase the risk for tick bite and infection include the following:

• Camping
• Fishing
• Gardening
• Hiking
• Hunting
• Picnicking

Signs and Symptoms

Lyme disease may be asymptomatic or may produce symptoms that develop in three stages. The first stage causes flu-like symptoms (e.g., fever, headache, malaise, muscle pain) and the characteristic "bull's eye" rash, typically within 7 to 14 days of infection. These symptoms often resolve without treatment.

The rash begins as a red area at the site of the tick bite and gradually expands, often with central clearing, which produces the bull's eye. It can last from a few hours to several weeks and varies in size. Other types of rash have been noted, some of which resemble hives, eczema, sunburn, poison ivy, and flea bites. Dark-skinned people may develop a rash that resembles a bruise.

The rash may itch, disappear, and then return weeks later. In some cases, a single bite can cause rash to occur on several areas of the body.

The second stage develops in approximately 10% of patients and occurs weeks to months after infection. The bacteria spread throughout the body via the bloodstream and the lymphatic system, causing arthritis, rash, and eye inflammation. Second stage Lyme disease may also affect the heart and the central nervous system. This stage also may resolve without treatment.

Third stage Lyme disease can develop months to years after infection. This stage affects the musculoskeletal, ophthalmologic, cardiovascular, and central nervous systems. Symptoms include the following:

• Blockage in the chambers of the heart (atrioventricular block)
• Brain dysfunction resulting in memory loss (encephalopathy)
• Damage to nerves in the head (cranial neuropathy)
• Inflammation of the brain and spinal cord (encephalomyelitis) or membranes surrounding the brain (meningitis)
• Inflammation of the cornea causing decreased vision and eye pain (keratitis)
• Inflammation of heart muscle (myocarditis) or the membrane that surrounds the heart (pericarditis)
• Inflammation of joints causing pain, swelling, and structural changes (arthritis)
• Multiple rashes
• Rapidly progressive motor neuron paralysis involving inflammation of several peripheral nerves (radiculoneuritis)

Diagnosis

Diagnosis of Lyme disease is made based on clinical symptoms and case history. In cases of early stage disease, known exposure, and symptoms that suggest later stage disease, laboratory testing may support a diagnosis.

Laboratory Tests

First, enzyme-linked immunosorbent assay (ELISA) or immunofluorescent assay is performed on a blood sample to identify Borrelia burgdorferi and antibodies to the bacteria. If there is a positive result, it may be confirmed using the Western blot test, which can detect small amounts of antibodies.

Positive results may be seen years after a successfully treated infection or an infection that resolved on its own. A positive result does not necessarily indicate active infection.

Ticks can be tested for bacteria. The tick should be removed carefully with fine tweezers, grabbing it as close to the skin as possible, and placed in a clean container with a moistened cotton swab. Squeezing the tick or applying petroleum jelly, a burnt match, or alcohol can transmit the bacteria and should be avoided.

Lyme Disease, Overview, Causes and Risk Factors, Signs and Symptoms, Diagnosis reprinted with permission from podiatrychannel.com
© 1998-2008 Healthcommunities.com, Inc. All Rights Reserved.

Lyme Disease Resources

	Join Our Lyme Disease Forum Do you have a question, want to share medical advice, or just need to discuss your situation with someone else having a similar experience? The healthchannels forum is a resource for everyone to share and discuss their health and medical needs with others.	Advertising Disclaimer
	Living with...Share your story Do you have a personal health story that you would like to share with others? As a source of free patient education, our goal is to provide our users with trustworthy information and support from others. That's why we've started our "Living with..." sections.
	Our "Living With..." support pages are a place to share experiences about living with a certain condition, disease, disorder, or illness and for loved ones of those dealing with health-related issues. Many people, especially when newly diagnosed, find comfort in knowing that others are having a similar experience. Help others by sharing your story. View stories already submitted.
	Stay Updated Sign up for our newsletter and receive important updates on the medical conditions that are most important to you.
Are you interested in becoming a nurse? Take this test. Advertising Disclaimer To quickly access health information from your website's browser, download Healthcommunities.com's healthchannels toolbar.