The test is used to determine if your blood has made antibodies to the bacterium that causes Lyme disease. The infection impacts many body systems, and commonly starts with a ‘bulls-eye’ rash at the site of the bite and flu-like symptoms. The disease can progress and eventually cause a variety of chronic symptoms, including inflammation of the heart, arthritis, and central nervous system disease, including meningitis.

Because the symptoms of Lyme disease vary from person to person, and because antibodies to the bacterium do not appear until 6–8 weeks after the tick bite, the infection is difficult to diagnose. At this point, a blood test can be used to detect levels of antibodies, immunoglobulin M (IgM) and immunoglobulin G (IgG), that develop against the spiral Borrelia burgdorferi bacterium stages of infection although it also detects antibodies to other spiral bacteria, such as those that cause syphilis and leptospirosis. Therefore, if the test is positive an additional test called a Western Blot, is often required to confirm the presence of specific antibodies to the bacterium that causes Lyme disease. 

Other more specialised tests such as DNA testing by PCR and culture of the organism from skin biopsies are under development (see “Testing advice for NSW clinicians"). The NSW Department of Health recommends that testing should be performed in NATA-accredited laboratories (listed at www.nata.com.au).

If you have travelled overseas to an area with Lyme disease and you show typical signs of the tick bite. If you don’t have these clear signs but do have vague, confusing symptoms ranging from ‘flu’, numbness and muscle and joint ache to arthritis, fatigue and unexplained nerve or heart problems, your doctor may order these blood tests to rule out Lyme disease.

A healthy adult has no antibodies to the Borrelia burgdorferi bacterium. If you test positive, you may have been exposed to the bacterium and may have Lyme Disease, noting it can take from 6 to 8 weeks after being bitten for antibodies to appear in the blood.) If you test negative, you could still have the disease, but your antibody level is too low to detect.

The following table simplfies the test results. However the results have need to be interpreted by a doctor and in conjunction with clinical findings.

IgM antibody	Igg antibody	Confirmatory test (western blot)	Likely interpretation of lab tests
Positive	Positive	Positive	Strongly suggest Lyme disease
Positive	Negative	Negative	False-positive IgM test
Negative	Positive	Positive	Late or previous infection
Negative	Positive	Negative	False-positive IgG  test
Negative	Negative	Usually not performed when IgG and IgM are negative	No infections present, symptoms may be due to another cause OR antibody levels are too low to detect

Antibodies to these bacteria can stay in the blood for a long time so if you have ever been infected with Borrelia burgdorferi previously, your blood test might still be positive even though you may no longer have a Lyme disease infection.

Antibiotics can interfere with the test results. Therefore if you are being treated with antibiotics before being tested for Lyme disease your doctor should be informed.

Most patients with Lyme disease are treated with antibiotics.

Yes. If travelling overseas to USA or Europe and you are in the woods or garden in tick-infested areas, avoid contact with the soil, leaves, and vegetation. Wear closed shoes, light-coloured clothing and use insect repellant containing DEET. Check your clothing and exposed skin frequently and remove ticks promptly. Animals such as dogs, cats, horses and cows can also carry the deer tick.

The rash appears in only about 50% of those infected. This rash may be the classic ‘bull’s eye’ but may also be blotchy or red and may be confused with poison ivy, spider bites or ringworm. It may appear between a few days and a few weeks after being bitten and can disappear quickly. If possible, take a picture of the rash to show your doctor, since the rash may be gone before you can get an appointment.

Other symptoms of Lyme disease include fatigue, chills and fever, headache, muscle and joint pain and swollen lymph nodes. Check with your doctor if you have any of these symptoms and cannot explain how you got them.

Lyme disease is common in the US, particularly the forested areas of New England, and in Scandinavia. Other countries in Western and Eastern Europe, the former Soviet Union, Japan and China have all reported cases. Each year hundreds of thousands are infected in the US, while in the UK there are usually only a few hundred cases. Infections occur mainly in the northern hemisphere summer months i.e. June and July. Lyme disease has not been found to occur in Australia. In the 1990s, 12,000 ticks were collected from different parts of NSW and were tested for Borrelia bacteria but no evidence of Borrelia infection could be found in any of the ticks collected.

It is possible that a disease which shares some symptoms with Lyme disease is present in Australia. If it exists it may or may not be transmitted by ticks. However, until such a disease is characterised and the causative organism identified it is not possible to develop a diagnostic test. Some non-NATA accredited laboratories in Australia and overseas offer tests that claim to show Lyme disease is relatively common in Australia, but Australian expert microbiologists and pathologists recommend that testing be performed only in NATA-accredited laboratories where the testing has been assessed by strict criteria to assure that false-positive and false-negative results are minimised.