Should I get a test for Lyme disease?

A characteristic skin rash can appear that looks like the bullseye on a dartboard, called erythema migrans. It’s round, with a series of red rings inside one another, but it's not usually itchy or painful. The rash can take 1 to 4 weeks to appear, but it has been known to appear up to 12 weeks after a tick bite. It might persist for several weeks.

You may also suffer fever, muscle aches, headaches and tiredness, similar to getting the flu. In rare cases where it infects the nervous system, you may get a viral-like meningitis, a problem with one of the facial nerves (facial palsy) or other nerve damage, and all of these are reasons to seek urgent medical attention.

A blood test can look for Lyme disease – it specifically looks for antibodies against the Borellia bacteria, which are part of the immune response to fight any infection. These antibodies can take several weeks to develop and appear on the ELISA test, so if you have a negative result within 4 weeks of a bite and symptoms, and suspicion is high, you could repeat it 4 to 6 weeks later.

There’s a different type of test called the immunoblot test, available 12 weeks after symptoms started, and this is offered only if suspicion is high and earlier tests were negative.

Some people want to bring the suspect tick in for testing. This isn’t routinely done, as the tick may be infected but you may not. So our advice is that saving the tick won’t add any value to discussions with your doctor.

Unfortunately testing is not straightforward. You may get a false-positive result (the test says you have the infection, when in reality you don’t) or a false-negative result (the test says you’re clear, when you actually have the infection, therefore potentially depriving yourself of treatment).

If suspicion is strong from your history of a tick bite, location and the distinctive rash, then you may be offered treatment without waiting for the result of the test anyway. Your doctor will consider all the evidence and decide from there.

Treatment of Lyme Disease

You may feel it's worth just getting treatment anyway, what’s the harm? But any treatment carries the risk of unwanted effects: antibiotics can cause stomach upset, disruption of your gut microbiome, yeast infections like thrush, and prompt skin rashes or allergies. Doxycycline is the antibiotic usually used to treat Lyme disease, and it's given for up to a month. This increases the chance of gut disruption and other unwanted effects.

Doxycycline can cause skin rashes as it sensitises the skin to the harmful effects of the sun, so be sure to avoid the sun and wear lots of sunscreen and protective clothing when out.

Catching Lyme disease depends on three things: the tick species, where in the world you caught the tick, and how long it was biting you. No more than 1 in 10 of this particular tick species actually carry the bacteria, and an infected tick needs to be feeding on someone for at least 24 hours to transmit the bacteria. These ticks are only prevalent in certain grassy or wooded areas in the south and north of England or the Scottish Highlands, and they are only active from April to October.

Given the difficulties with suspecting Lyme disease and getting a positive test, it’s estimated that Lyme disease is underestimated in the UK. About 900 cases are recorded a year, but it’s estimated the true figure of those infected is closer to 2000 to 3000 people.

Hopefully this builds a picture of the chances of you contracting Lyme disease as being pretty low, although rare long-term and serious effects are not to be underestimated.