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Monday, 5 March, 2001, 01:35 GMT
Test for tick disease
Pheasants carry the bacteria that cause Lyme disease
Scientists have developed a more accurate way to test for a Lyme disease, an illness that left untreated can cause serious illness.

The test may eventually also provide a more effective way to diagnose other diseases such as lupus, infectious hepatitis and multiple sclerosis.

Lyme disesase is caused by a bacteria which is transmitted to humans through tick bites.

One of the first symptoms is usually a characteristic bullseye-shaped rash.

It should be possible to amend the technique such that it can detect the UK strains

Dr Klaus Kurtenbach, Oxford University
Sufferers can also experience joint pains, fever and fatigue, and as the bacteria continues to spread around the body. Other symptoms can include a stiff neck, facial paralysis or nerve tingling.

If untreated, symptoms can worsen to include severe headaches, painful arthritis and joint swelling, heart problems and even mental disorders such as short term memory loss and difficulty concentrating.

If caught early, the disease is treatable with antibiotics - however, late stage Lyme disease does not respond as well.

Difficult to diagnose

The disease is becoming increasingly common, but can be difficult to diagnose.

Symptoms can be confused with other conditions such as rheumatoid arthritis.

In addition, the characteristic rash only occurs in 60%-80% of patients and may fade before a patient sees a doctor.

The current diagnostic blood test is based on detecting antibodies produced by the body's immune system in response to infection.

However, other diseases also stimulate production of the same antibodies, and so some patients are wrongly diagnosed as suffering from the condition.

The test can also detect antibodies left over from a bout of infection that has been cured.

However, there is also a risk that some people with the earliest stages of the infection are not picked up because the test is not sensitive enough.

More accurate

Now a researcher from the Children's Hospital of Philadelphia has developed a more accurate blood test.

The new method detects a tell-tale protein - called OspA - that often remains hidden from the routine blood test currently in use.

OspA is produced specifically by Borrelia burgdorferi, a bacteria that causes Lyme disease.

The test was tried out on a patient who had developed the characteristic skin rash associated with Lyme disease, but had tested negative for the disease in three standard blood tests. It successfully detected the disease.

Dr Michael Brunner, who developed the test, said: "The test can identify early disease, and also can distinguish active disease from evidence in the blood of a past disease."

However, he said much more work was needed before the test could be made widely available.

Dr Klaus Kurtenbach, of the Wellcome Trust Centre for the Epidemiology of Infectious Disease at Oxford University, told BBC News Online that the new technique sounded "good in principle".

However, he said the majority of cases of Lyme disease in the UK were not caused by Borrelia burgdorferi, but by a separate species Borrelia garinii.

He said: "It should be possible to amend the technique such that it can detect the UK strains.

"However, it remains to be tested whether this would work in reality as the different Borrelia strains differ in their pathogenic (disease causing) potentials."

The research is published in the Journal of Immunological Methods.

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06 Oct 99 | Medical notes
Lyme disease
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