For 30 years Miranda Hart suffered from a debilitating mystery illness which, at its worst, left her feeling as if she was ‘wading through treacle’ and even bed-bound.

The 51-year-old comedian and actor was initially told that her symptoms – which began when she was a teenager, living in the US state of Virginia – were, among other things, agoraphobia.

It was only recently that she was finally diagnosed with Lyme disease, following several blood tests after hitting ‘rock bottom’, as she described it recently.

It was then that some ‘very clever’ experts were able to join the dots and diagnose her with Lyme disease. This is an infection caused by a group of bacteria known as Borrelia, and it is transmitted by an infected tick.

Unfortunately Miranda had also developed chronic fatigue syndrome as a result – a not uncommon complication of the disease.

And while the star’s health has improved, she’s not yet ‘fully recovered’, she says.

Public Health England estimates there could be around 3,000 new cases of Lyme disease a year – however the charity Lyme Disease UK suspects the real number to be ‘at least three times higher’. Cases are rising – one theory is that the increase in new, urban green spaces is providing more habitats for ticks to live and breed.

Our changing weather may be another reason, explains ecologist Nathan Orr, a ranger in the Mendip Hills.

‘We think the warmer and wetter weather hasn’t caused a die-out of populations you would normally see when it’s a much colder winter.’

Better surveillance of ticks and their habitats, as well as greater awareness of the disease, may also contribute to the increase in cases diagnosed.

The consequences for those affected can be crippling – a study published last year in The Lancet Regional Health Europe journal found that almost a third of people who get Lyme disease will have persistent symptoms, such as memory loss, fatigue and pain – a condition often referred to as post-treatment Lyme disease syndrome (PTLDS).

So why is Lyme disease on the rise in the UK, and how can you protect yourself against it and its long-term complications?

Lyme disease is an infection carried by ticks, which feed off the blood of mammals including humans – its name comes from the US town of Lyme, in Connecticut, where it was first identified in 1975.

‘The insect can bite anywhere on the body but prefers warm, moist environments such as behind the knee or in the groin,’ explains Dr Sally Mavin, a clinical scientist and director of the Scottish Lyme Disease and Tick-borne Infection Reference Laboratory in Inverness.

Other preferred spots include the hairline and behind the ears, ‘which people don’t tend to check’, she adds.

Once you’ve been bitten, the bacteria carried by the tick enter your bloodstream. It can then travel throughout your body and cause inflammation in the joints, heart and nervous system, resulting in symptoms such as tiredness and aches.

Ticks look like tiny, spidery creatures and can range from the size of a poppy seed to a sesame seed.

‘They’re generally found in woodland and moorland areas,’ explains Sally Cutler, a professor in medical microbiology at the University of East London.

‘Ticks are increasing in numbers and extending the regions where they live, so risks are changing too. They can be in urban parks or even your back garden – anywhere.’

Exposure to certain animals can increase risk, adds Dr Lucy Gilbert, a senior research fellow in ecology and environmental change at the University of Glasgow.

Deer carry a lot of ticks, although not the disease-causing bacteria – these come via rodents, birds and other wildlife such as squirrels and hedgehogs.

‘Therefore, for an area to have high Lyme disease risk, it needs some deer [to maintain a tick population], plus plenty of other wildlife [to transmit the disease-causing bacteria],’ explains Lucy Gilbert.

While domestic animals such as cats are not a direct source of infection in people, they can carry an infected tick into your house which, if brushed against, could attach itself to a human. You can’t catch Lyme disease from another person.

The longer a tick is left to feed, the higher the chances are that it will pass on any diseases it’s carrying.

But while speed is of the essence, it’s vital to remove it properly: leaving behind the tick’s mouth parts can cause an infection, which in severe cases can lead to abscesses or even septicaemia (blood poisoning).

Squashing or puncturing a tick as you remove it may also cause its saliva or other fluids to get into your bloodstream and so spread the disease-carrying bacteria. For the same reason, don’t try to freeze or burn it off either.

Use fine-tipped tweezers to get close to the tick’s head – you can get specialist versions, such as Lifesystems Tick Tweezers (£3.99) from a pharmacy.

‘Hold the tweezers horizontally along the skin, to avoid squashing the tick,’ explains Dr Mavin.

‘Grasp it firmly with the tweezers where the tick’s mouth meets the skin then slowly and steadily pull the tick upwards with even pressure. Don’t attempt to twist or jerk the tick out.

‘Make sure you get the whole tick – don’t leave the head buried under the skin. After removing it, clean the area with an antiseptic wipe and wash your hands.’ You don’t need to see a doctor unless you feel unwell.

Sometimes the tick will fall off on its own after sucking your blood for three to six days – and you may not spot it.

One obvious sign you’ve been bitten is a rash. Around 60 per cent of people will develop the classic Lyme disease rash – known medically as erythema migrans.

This looks like a bullseye target around the bite, spreading around a central point as it gets bigger. The rash is caused by an inflammatory reaction to the bacteria as they spread from the bite.

‘But it might not always look so specific,’ adds Dr Mavin, ‘so it’s important to remember that any spreading rash which is more than 5cm (or roughly the size of a 50p coin) may well be a tick bite.’

And while the rash usually appears within the first few weeks of the bite , ‘it can appear up to three months after, so it’s important to speak to a doctor if you know you’ve been bitten and then start to feel unwell with flu like symptoms’, adds Dr Sanjay Mehta, a GP at The London General Practice.

Your GP can look for Lyme disease with a blood test to check for antibodies – proteins produced by the immune system to neutralise harmful substances – to the Lyme bacteria: these would suggest you’ve been bitten by an infected tick.

However, there is some controversy about the accuracy of the test used in the NHS and possible false negative results.

Meanwhile, the EliSpot Test is available mostly through private labs (especially in Europe), who maintain it is more sensitive in detecting chronic Lyme infections as it focuses on immune cell activity (rather than antibodies), showing the body is fighting an infection, which may persist longer in chronic cases.

Treatment usually involves antibiotics such as doxycycline for up to three weeks to clear any infection.

‘If the person has a history of a recent tick bite but is otherwise well, the general advice is to avoid antibiotics – to reduce the risk of antibiotic resistance – but instead to observe for any symptoms or the development of a rash surrounding the original tick bite.’ says Dr Mehta.

The longer you leave an infected tick embedded in the skin, the higher your risk of contracting Lyme disease. And the later you leave it without treatment, the more likely you are to get long-term and (more rarely) persistent symptoms.

There is some controversy over PTLDS symptoms – whether these are caused by active infection from the bacteria or an immune system reaction after the infection has been cleared.

As Professor Cutler explains, often those who have had Lyme disease still have a positive blood test status even though they have been successfully treated. With PTLDS symptoms, therefore, it ‘could be that the immune system is still trying to fight the bacteria, even though the bacteria are long gone, but this results in prolonged symptoms’.

There are also questions over whether chronic Lyme disease should be treated with long-term antibiotics – both the National Institute for Health and Care Excellence (NICE) and the World Health Organisation caution against prolonged use due to potential risks because of increased resistance to the drugs.

Miranda Hart has said she deals with her symptoms through managing her energy levels and ‘finding joy in small things’.

Prevention is the key. It doesn’t take much contact for a tick to get on to your body – if you brush against something ticks are on, such as long grass, they can climb onto your skin.

So if you’re going into parkland, woodland or the countryside, cover up as much as you can, says Professor Cutler.

‘Tuck your trousers into your socks or wear wellington boots. And wear light-coloured trousers, as it’s easier to see ticks on them.’

Use an insect repellent specific to ticks, mosquitoes and other biting insects, he adds – these contain DEET (N,N-diethyl-meta-toluamide), a chemical that works by making skin unpalatable to ticks, which reduces the likelihood of a tick bite.

‘And carry a tick-removal tool – this is the size of a credit card and has a magnifying lens and two removal tools (that look like hooked tweezers) for different sized ticks,’ says Professor Cutler.

When out hiking, sticking to paths rather than the long grass will also help. ‘Check yourself over in the shower after going into tick-infested areas for any signs of being bitten.’