Doctor's Notes on Lyme Disease
Lyme disease (also called Lyme infection or borreliosis) is a bacterial illness transmitted to humans from the bite of deer ticks (Ixodes ticks) carrying the Borrelia burgdorferi bacterium. Lyme disease is most commonly found in the Northeast, Mid-Atlantic, North Central, and Pacific coastal regions of the U.S. and in Europe.
Early symptoms of Lyme disease develop within three to 30 days after a tick bite and include fever, chills, headache, fatigue, muscle and joint aches, swollen lymph nodes, and feeling unwell (malaise). A rash that is warm to the touch but is not painful or itchy may also occur. In some people, the rash can appear as a target with multiple rings called a “bull's-eye” lesion. Symptoms in children are similar, though younger children are more likely to have skin lesions on the head or neck and older children on the extremities. Days to months later, additional serious symptoms of Lyme disease may occur and can include facial palsy (Bell's palsy), meningitis, nerve inflammation, shooting pains that may interfere with sleep and cause insomnia, muscle weakness, brain swelling (encephalitis), intermittent episodes of arthritis, pain in the tendons/muscles/bones, shortness of breath, heart palpitations or an irregular heartbeat, dizziness or passing out, inflammation of the brain and spinal cord, and short-term memory problems.
Lyme Disease Symptoms
Early signs and symptoms of Lyme disease occur from three to 30 days after a tick bite and include the following:
- Muscle and joint aches
- Swollen lymph nodes
- General feeling of being unwell (malaise)
The initial infection can occur with minimal or no signs or symptoms. But many people experience a flu-like primary illness or a characteristic rash several days to a few weeks following a tick bite. This rash may feel warm to the touch but is rarely itchy or painful.
The flu-like illness usually occurs in the warm weather months when flu (influenza) does not occur.
The rash is a red rash that grows in size daily. It is called erythema migrans and occurs in about 70%-80% of infected individuals.
The U.S. Centers for Disease Control and Prevention (CDC) defines this rash as a skin lesion that typically begins as a red spot and expands over a period of days to weeks to form a large round lesion, at least 5 cm (about 2 inches) across, and up to 30 cm (12 inches). A red circular spot that begins within hours and is smaller is usually a reaction to the tick bite.
When the rash occurs at the site of the tick bite, it is called a primary lesion. Multiple secondary lesions can occur that are a reaction to the infection and are not due to multiple tick bites. All of these lesions can enlarge to the size of a football. This growth in size of the red spots on the skin is characteristic of Lyme disease.
The red spots may be circular or oval.
As it grows, the rash can remain red throughout, although it often can develop a clear central area. In a minority, it may take on the appearance of a target with multiple rings (alternating red with clear skin), called a bull's-eye lesion.
Symptoms and signs in children are similar, though younger children are more likely to have skin lesions occur on the head or neck and older children on the extremities.
Left untreated, signs and symptoms of the primary illness usually will go away on their own within a few weeks, although the rash may recur.
Days to months later, additional symptoms of Lyme disease may occur. The organs affected later in the course of the disease may lead to the following conditions and complications:
- Facial palsy (Bell's palsy) is paralysis of the facial nerve that causes the facial muscles to be uneven and droop. This may get better without treatment.
- Meningitis causes headache, fever, and stiff neck.
- Nerve inflammation causes pain, numbness, and tingling in the arms or legs.
- Shooting pains may interfere with sleep and cause insomnia.
- Muscle weakness
- Brain swelling (encephalitis) causes learning difficulties, confusion, and dementia.
- Intermittent episodes of arthritis last about a week and usually involve the knee or wrist. This involves severe joint pain, stiffness, and swelling. These may recur over periods of weeks to months, and if the Lyme disease remains untreated, about 10% of people who have these episodes develop persistent arthritis in the knee. Occasionally, people with Lyme disease can present with an acute arthritis in the knee without a clear history of a rash or other joint complaints.
- Pain in the tendons, muscles, and bones.
- Episodes of shortness of breath.
- Inflammation of the heart (carditis) results in heart palpitations or an irregular heartbeat (Lyme carditis), which can also result in dizziness or passing out.
- Inflammation of the brain and spinal cord
- Difficulty with short-term memory
Lyme Disease Causes
B. burgdorferi bacteria cause Lyme disease. The bacteria have a complex life cycle, spending part of their life in the deer tick and part in some mammals such as mice and deer.
Humans are not a part of the bacterium's life cycle but can become infected when bitten by the tick. Lyme disease is not contagious and cannot be passed from person to person.
While dogs and cats can get Lyme disease, there are no reported cases of these animals spreading the disease to their owners. However, dogs and cats can bring the infected ticks into the home, which is one reason why tick protection for pets is important. Talk to a veterinarian about the right type of tick control for any pets.
Risk factors for getting Lyme disease include the following:
- Living in the northeastern or Midwestern U.S. states where the disease is most prevalent
- Being outdoors in the woods or areas that have tall grass, shrubs, or brush
- Fishing, camping, hunting, yard work, hiking, and other outdoor activities in tick-infested areas
- Having bare, unprotected skin when outdoors in high-risk areas
- Pets who are not protected against ticks may bring them indoors.
- Not removing attached ticks promptly
Lyme disease is caused by spiral-shaped bacteria called Borrelia burgdorferi (found in the U.S.) and Borrelia afzelii (found in Europe). Two different species of ticks, Ixodes scapularis and Ixodes pacificus, transmit the bacteria to humans via bites.
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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.