by Lois Rogers. This article appeared on 31 March 2008.
ME, the crippling disease you can catch just by going for a walk
Sarah Warren thought she was coming down with flu.
After a marathon weekend of biking and running in the summer of 2005, the superfit primary school teacher assumed she'd overdone it.
Her head was pounding, her muscles ached and she was exhausted.
"What hit me was like a combination of the worst flu, the worst jet lag and the worst hangover I've ever had," says Sarah, 40.
"I'm usually very active and healthy so I didn't have a clue what was wrong with me.
"At first, I didn't think about going to the doctor or taking any medicines because I simply thought I needed more early nights.
"But after about a month of feeling terrible I decided to see my GP, who was equally bemused and told me to rest."
But the symptoms soon began to take over Sarah's life. She suffered agonising headaches, inexplicable muscle pain, and other nerve problems, including mysterious numbness in her fingers and toes.
"Because I don't like taking medicines, I ploughed through work during the day and in the evening tried to get more sleep," says Sarah, who is married with two children.
"I didn't have a clue what was causing it."
For five months, her symptoms were intermittent, although always excruciatingly painful.
But then they started to come on with increasing severity.
"I was getting more and more annoyed," she says, "because my quality of life was severely affected but no one knew what it was."
Sarah, who lives in Colchester, Essex, returned to her GP and saw a locum who suspected an immune system disorder.
He referred her to a chronic disease clinic attached to her local hospital and at first thought she might be one of Britain's estimated 250,000 sufferers of myalgic encephalitis (ME), otherwise known as chronic fatigue syndrome.
"By this point I was so ill I couldn't think straight," says Sarah.
"The doctors test for ME by ruling out other illnesses, so I had blood tests for leukaemia, lupus, anaemia, thyroid function – you name it.
"But even after all the tests, they couldn't confirm what was wrong and started looking for psychological factors.
"That annoyed me even more. I didn't worry that I had anything sinister, but I was desperate to find out what was wrong."
Unbeknown to Sarah – and her medical team – she was actually suffering from Lyme disease, a little understood condition which is spread by bloodsucking ticks carrying the borrelia bacteria.
Lyme disease is endemic in heathlands and woods in central and western Europe and North America.
Last summer the White House disclosed that President Bush had been treated for Lyme disease after, it is thought, he was bitten by an infected tick at his ranch in Texas.
But the disease was only recognised as a problem in the UK in 1986.
The number of Lyme disease infections here has rocketed from a tiny handful to almost 3,000 a year, according to Health Protection Agency estimates.
This might still not reflect the real figure, however, because France, with a similar population and lifestyle to the UK, has an estimated 10,000 cases a year.
It's not known how Lyme disease spread to Britain, but it is believed that global warming is contributing to the rapid proliferation of ticks in our countryside.
People involved in outdoor activities are advised to cover their legs because of
the risk of being bitten.
Ticks often live on our growing wild deer population, and can be spread via dogs and any other warm-blooded animal.
Sometimes a rash appears around the site of the tick bite, showing the spread of the bacteria, in a process which may take up to a month from the initial bite.
However, as in Sarah's case, the infection can often enter the body leaving no outward signs at all.
In more serious cases, the bacteria can also enter the nerves, causing meningitis, which can be fatal.
The factors which influence whether an infection is non-existent-mild or debilitating, are not understood.
The disease itself is not fatal, but left untreated it can also cause crippling heart or nerve damage, and debilitating arthritis.
But while there is growing concern that the bacteria are rapidly increasing in the environment, doctors are either failing to recognise the symptoms or misdiagnosing it as something else – often ME.
And although ME was recognised by the National Institute for Clinical Excellence last year as a genuine illness, there is growing dispute over how many ME sufferers may actually have Lyme disease.
It is notoriously difficult to diagnose. Blood tests available are believed to identify only 50 per cent of cases.
This is for two reasons: the tests are designed to recognise antibodies to the Lyme disease bacteria and not everyone infected seems to produce them.
Plus, the bacteria and antibodies may be concentrated deep in the organs and not circulating in the blood, so remain undetected.
"There is a big issue about how good these tests are," says Sarah Randolph, professor of parasite ecology at the University of Oxford, who is studying the rise of tickborne disease across Europe.
"People who are ill want to be told exactly what is wrong with them. Often that doesn't happen, or it may take many months or years, or may be confused with all sorts of other things.
"There is undoubtedly a problem with people being told they have ME or chronic fatigue syndrome, when it's actually Lyme disease.
"I feel it is irresponsible of doctors to simply ignore it.
"I get e-mails and phone calls all the time from people saying their GPs are unaware of the disease and are not helping them deal with the cause of their sudden and mysterious fatigue."
For Sarah, it took more than a year to get a diagnosis – and only as a result of further exhaustive blood tests at the private Breakspear Hospital in Hertfordshire, a recognised unit specialising in the diagnosis of unusual conditions.
She is now undergoing a year-long course of doxycycline, a potent antibiotic and an extreme measure intended to kill the infection once and for all – but it has affected her life dramatically.
"It wasn't until after I'd been properly diagnosed that I realised the previous doctors had been asking me questions about what sort of person I am – was I competitive, a perfectionist, that sort of thing.
"They were implying I was imagining my symptoms, and had made me wonder if I was going mad, which is infuriating."
Sarah's condition also forced her to give up full-time work.
And although she is now able to work part-time, she is by no means fully recovered.
"There is no way I can run around with my children as I don't have the energy.
"Now I manage to keep going most days doing the cooking and shopping and taking them to school, but sometimes I still have to go to bed during the day.
"Most of the time I'm too tired to see my friends. However, I'm determined to get better because being like this is both boring and lonely.
"What has happened to me has been a nightmare and I lost a valuable part of my life by not being diagnosed.
"It is vital more people become aware of Lyme disease and the terrible effect it can have. I wouldn't wish this on anyone."