What is Lyme disease?
Lyme disease is a tick-borne illness caused by the bacterium Borrelia burgdorferi. Only certain tick species transmit the infection — these species are found in Asia, Europe and North America. So far, there is no conclusive evidence that there are infected ticks in Australia.
Lyme disease symptoms
The first symptom in 70-80 per cent of people infected with Lyme disease is a rash called erythema migrans. The rash appears at the site of a tick bite, between 3 and 30 days after being bitten. It starts as a red dot around the bite, and then slowly expands to form a bull’s-eye pattern, with a red outer ring surrounding a clear area in the middle. The rash is not usually itchy or painful.
Sometimes the rash also appears elsewhere on the skin away from the tick bite, which is a sign that the bacteria are multiplying in the bloodstream.
Other Lyme disease symptoms can develop a couple of days to a few weeks after the rash first appears, and include:
- joint pain; and
- muscle pain.
In the 20-30 per cent of people who do not develop the hallmark erythema migrans rash, these symptoms may be the only evidence of infection.
Untreated Lyme disease can be associated with other problems, including:
- ongoing episodes of severe joint pain and swelling;
- meningitis (inflammation of the membrane surrounding the brain);
- inflammation of the eyes;
- hepatitis (inflammation of the liver);
- problems with short-term memory;
- heart problems (such as an irregular heartbeat); and
- nerve problems such as Bell’s palsy (temporary paralysis of one side of the face) or numbness, weakness and shooting pains in the limbs.
It’s possible for some complications to develop months to years after an untreated infection with Lyme disease.
What causes Lyme disease?
Ticks attach themselves to their hosts (humans and other warm-blooded animals) and feed on the host’s blood. As they are feeding, ticks can transmit bacteria to their host. You can catch Lyme disease if you are bitten by a tick that is infected with the Borrelia burgdorferi bacterium.
Lyme disease is the most common tick-borne illness in North America and Europe. The ticks that cause Lyme disease are often found in grassy and heavily wooded areas, and infections are more common in summer than at other times of the year.
Lyme disease cannot be passed from person to person.
Your doctor will take your history, including recent travel history, and perform a physical examination.
Diagnosing Lyme disease can be difficult because many of the symptoms and signs are non-specific and similar to those of other conditions, such as the flu and other viral illnesses. The rash is the only symptom that is unique to Lyme disease, but not everyone develops the rash. Also, ticks are very small and their bites are usually painless, so some people may not realise that they have been bitten.
The following tests can help to confirm a diagnosis of Lyme disease. These tests are highly specialised and are not always readily available in all areas. Testing for Lyme disease should be performed by laboratories that have accreditation from the National Association of Testing Authorities (NATA).
- Enzyme-linked immunosorbent assay (ELISA). This test detects antibodies produced by your immune system against the Borrelia burgdorferi bacteria. It is most reliable if performed within 4-6 weeks of suspected infection.
- Western blot test. A second test for antibodies, called a Western blot test, can be done if the ELISA is positive, to confirm the result.
- Polymerase chain reaction (PCR) is a test that can be used to detect DNA from the bacteria that cause Lyme disease.
Treatment of Lyme disease
Lyme disease can be treated with antibiotics. People treated promptly in the early stages of the disease usually make a full recovery. When treatment is delayed, the response to treatment may be slower but most people still make a complete recovery.
Post-treatment Lyme disease syndrome
About 10-20 per cent of people with Lyme disease will continue to have symptoms after treatment with antibiotics. This is known as post-treatment Lyme disease syndrome.
Symptoms typically include:
- sleep disturbance;
- problems with memory and concentration;
- joint pain; and
- muscle aches.
Post-treatment Lyme disease syndrome (also sometimes referred to as chronic Lyme disease) can last for 6 months or more. Unfortunately in some cases, recovery from post-treatment Lyme disease syndrome takes months or years.
Lyme disease in Australia
There have been instances of Lyme disease confirmed in Australia, but in these cases the infection was found to have been acquired overseas. According to NSW Health, there is currently little evidence that locally-acquired Lyme disease occurs in Australia.
There are, however, other infections caused by Australian ticks that can cause symptoms similar to those of Lyme disease.
Preventing tick bites
The following precautions can help prevent you from being bitten by a tick when outdoors, especially in grassy or heavily wooded areas.
- Wear clothes that fully cover your arms and legs.
- Tuck your trousers into your socks.
- Wear a wide-brimmed hat.
- Apply insect repellent that contains DEET to clothes, hats and skin.
- Shower and check for ticks soon after being outdoors in areas known to have ticks.
Removing a tick
The risk of developing Lyme disease is low if the tick is removed within 24 hours, because ticks need to be attached to your skin for at least 36 hours before the Borrelia burgdorferi bacteria can enter your bloodstream. So removing a tick as soon as you notice it can prevent infection.
Use fine-tipped tweezers to grab hold of the tick as close to the skin as possible. Gently pull the tick straight out (without twisting), being careful to remove the whole tick. Avoid using methylated spirits, kerosene or other chemicals — this may cause the tick to inject more toxins.
Once the tick has been removed, clean the area with an antiseptic or soap and water.
See your doctor if you are having trouble removing a tick or are concerned about tick-borne illnesses.
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