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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Lyme disease

What is Lyme disease?

Lyme disease is an infection caused by Borrelia burgdorferi sensu lato complex, a type of bacteria called a spirochaete. Humans and animals are infected with the bacteria through tick bites on the skin. Infected Ixodes ticks are often found on deer. The disease is common in parts of the United States but may also exist throughout much of the world. In New Zealand, cases have only been reported in people that have recently travelled from an endemic area.

What happens after a tick bite?

Several things can happen after being bitten by an infected tick.

Ixodes tick
Ixodes tick
Erythema chronicum migrans Erythema chronicum migrans
Erythema chronicum migrans Erythema chronicum migrans Erythema chronicum migrans
Erythema chronicum migrans

What are the signs and symptoms?

Although Lyme disease can affect any part of the body, it appears to most often affect the skin, heart, central nervous system, joints and eyes. The disease can basically be divided into 3 stages according to the extent of infection. In individual patients there is no rigid cut-off between each stage.

Stage Features
Localised Lyme disease
  • Erythema migrans, the rash characteristic of Lyme disease, appears usually 7-10 days (range 1-33 days) after a tick bite
  • The tick takes about 36 hours to transmit the borrelia, so early removal of a tick prevents infection with Lyme disease
  • Appears either as a single expanding red patch, or a central spot surrounded by clear skin that is in turn ringed by an expanding red rash (looks like a bull's-eye) centred on the tick bite
  • Erythema migrans is thought to occur in 80-90% of all cases of Lyme disease
  • Lymph glands near the tick bite may be swollen
  • 'Flu-like illness with low-grade fever, chills, fatigue and joint pain may occur briefly and then recur if the disease progresses
Disseminated Lyme disease
  • Eythema migrans now appears in multiple sites on other parts of the skin
  • Other symptoms include severe fatigue, headache, stiff and aching neck, tingling or numbness in extremities, facial paralysis, sore throat, fever, abnormal pulse, changes in vision and multiple enlarged lymph glands
  • Progression is gradual over months to years
Late Lyme disease
  • Arthritis (pain and swelling) in one or more large joints
  • Neurological disorders such as disorientation, confusion, dizziness, lack of concentration, short-term memory loss
  • Numbness extending to hands/arms and feet/legs

Diagnosis of Lyme disease

It is important to get early diagnosis if you think you may have Lyme disease. Diagnosis can be made on the presence of erythema migrans and other symptoms, plus the evidence of a tick bite. Laboratory tests are usually not performed within the first month after initial infection, as these can be unreliable.

Undetected or ignored early symptoms may be followed by more severe symptoms weeks, months or even years after the initial infection. Certain laboratory tests are then recommended to confirm diagnosis, but can be misleading.

New evidence reports tick bites may transmit other infections. Their significance is unclear.

What treatment is available?

Localised or early Lyme disease generally responds well to appropriate antibiotics. Full cure is usually achieved if the disease is diagnosed and treated promptly, but the cure rate decreases the longer treatment is delayed. The choice of antibiotic depends on bacterial sensitivity. Antibiotics used include, amoxicillin, doxycycline, azithromycin, cefuroxime, erythromycin, penicillin VK and cetriaxone. The route of administration and the duration of course is still under debate and being defined. Current duration of treatment is somewhere between 10-30 days. Late stage Lyme disease should be treated with intravenous antibiotics.

Some patients have persistent symptoms after apparently successful antibiotic treatment for Lyme disease. In at least some of these people, their symptoms are probably not due to Lyme disease. There is on-going debate whether borrelia can survive in some humans after treatment with standard courses of antibiotics.

Related information

References:

Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.

On DermNet NZ:

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Author: Vanessa Ngan, staff writer

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.