Low take-up of the MMR jab could soon cause outbreaks of measles in Britain. Jeremy Laurance visits Freiburg in Germany, where a middle-class boycott of vaccinations is causing rates of infection to soar - with tragic results

Fate has been cruel to Claudia Hess. The smiling teenager, whose ambition was to work with animals in the hills of the Black Forest in southern Germany where she lives, has been robbed of her future by an illness that need never have happened.

One day in winter, she and her twin, Bernadette, began to cough, splutter and then to sizzle. The doctor diagnosed an allergy. Both girls developed a rash and a fever but then their paths diverged. While Bernadette made a rapid recovery, Claudia worsened. After being ill for a week, she woke up one morning unable to see. By the afternoon she had lost the power of speech.

She was rushed to the University Children's Hospital in Freiburg, about 170 miles west of Munich, where doctors pronounced that she had the worst case of encephalitis - swelling of the brain - they had seen. Once they examined her sister Bernadette they knew the cause: measles.

Germany suffered more outbreaks of measles than any other European country in 2002, the latest year for which comparative figures are available. There were 4,665 cases compared with 327 in the UK, a country with only a slightly smaller population. Yet vaccination coverage in Germany is good, at more than 90 per cent, compared with 80 per cent in the UK.

The reason for the outbreaks is the pockets of low-vaccination coverage that allow the once-rare condition to get a hold. In the winter of 2001, an outbreak in the tiny area of Coburg to the north, which started in an anthroposophical school opposed to vaccination, infected 1,100 people, of whom 398 developed complications such as pneumonia and 21 were hospitalised.

In Freiburg, a pretty university town similar to Oxford or Brighton, where a vaccination boycott is now firmly entrenched, outbreaks on a smaller scale occur regularly. Some parents refuse all vaccinations but most resist only those against what they consider mild illnesses. Local doctors estimate that in some areas coverage against measles, mumps and rubella has slipped below 60 per cent.

But there are important differences between the vaccination boycott in Freiburg and the anti-MMR (measles, mumps and rubella) campaign by parents in Britain. In Britain, the resistance to vaccination is driven by fear - of a reaction to the vaccine that could trigger autism. In Freiburg, the vaccine refuseniks are drawn from the Green-voting middle class intelligentsia who say they are making a positive choice - for a natural lifestyle in which their children will be exposed to common illnesses that help strengthen their immune systems.

On a Thursday evening at Oma Kuche's, a busy restaurant in the Wierhe district of the city, I approached five tables and on four I found diners opposed to vaccination.

Gisela Schaifer, 38, had her son, Fabian, covered against the major diseases - including diphtheria, tetanus and polio - but not against measles, mumps and rubella. "They pose a small risk, and the risk of the vaccine may be greater. It is crazy babies get six vaccines together. You would not get six diseases at the same time in nature." She is a qualified nurse, but her medical training has not persuaded her of the necessity of vaccination. "There is too much medicine. It is all about the profits of the pharmaceutical companies. That is why there is a trend to natural medicine in Germany."

At another table, eight women who were all members of the same childbirth group were having their monthly get-together. Five of them had refused vaccination. Astrid, mother of Luis, two, and Finn, nine months, said: "It is not necessary. Measles, mumps and rubella are good for their development - it's natural." Heike, cradling 10-day-old Bent on her shoulder, said: "When we were children these vaccines did not exist. We had measles, mumps and rubella and there was no problem." Most had given their children diphtheria, tetanus and polio jabs, but one, Silke, the mother of two-year-old Matti, had rejected all vaccinations. She did not offer an explanation.

Some fear that this back-to-nature, anti-science movement could spread, increasing the risk of public health disasters elsewhere in Europe. Dublin saw an outbreak of measles in the winter of 1999 that ended with 111 children in hospital, 13 in intensive care, seven on ventilators and three deaths. Vaccination rates against MMR have fallen as low as 62 per cent in parts of London and the Health Protection Agency warned this month that measles outbreaks were inevitable.

Robert Blood, a British communications consultant living in Freiburg, said: "In England, if you look where Green Party support is high - Islington, Oxford, Brighton - that is where you will find these developments. It is part of the ecological movement that has been evolving since the 1960s. They aren't trying to convert anybody; they are simply making positive lifestyle decisions along with their neighbours. It is something the medical profession is going to have to live with."

The casualties are people such as Claudia. She spent three weeks in intensive care on a ventilator, and a further three months in hospital. She was then moved to a rehabilitation unit 200km from her home, where she spent 15 months learning to speak, dress and feed herself again. Today, aged 19, she remains in a wheelchair and attends a special school where she is trying to catch up on lost years of education. "I was very sad about what happened to me but now I see things differently. Maybe it is just time passing," she says.

She smiles a lot and and speaks little. She wears a blue scarf knotted at her throat, which she unties to reveal the scar from her tracheotomy - the point where the ventilation tube was inserted into her throat to help her breathe. Family photos show the smiling 14 year old flanked by her sisters dressed in costume for the local carnival that marks the end of winter. It was her last memory before she fell ill.

Sitting in the hot little living room of their house, with its crucifix and religious icon on the wall, the Hess family contemplates what happened with regret but without blame. Claudia's illness was an accident. Ursula, her mother, simply forgot to get her daughters vaccinated. "I ask myself why didn't I do it? Was it God's wish or was it fate? Probably there is a grand design. Some things must happen," she says. Her husband, Helmut, is a lorry driver and she ran the village shop from their home in Elzach. The couple had five children - a son followed by two sets of twin daughters. As busy working parents it was hard to keep all the vaccinations for their five children up to date. In Britain, they would have received reminders but in Germany, where the doctors are paid for each treatment they administer, that is illegal. It is regarded as touting for business. The only protection for parents who forget is the "herd immunity" of the local population.

In Freiburg, that has dropped perilously low. At the St Christopherus kindergarten in the Wiehre district, which advertises its ecological credentials with grass on the roof, Brigitta Litzkow, the head teacher, estimates "about half" of the 72 children have been vaccinated against measles, and fewer against mumps and rubella. "Normally it is given as a combination vaccine [MMR], but if they find a doctor willing they can get single vaccines," Litzkow says. "Some doctors don't want to give vaccinations at all - their advice is counter to the traditional view. There is an anthroposophical movement here."

St Christopherus displays a notice when there is an illness in the kindergarten, which is required in Germany, to warn parents to keep their children away, or to bring them in if they want them to have the disease. Some parents organise "measles parties" to spread the disease deliberately.

Sabine Trunz, 40, who is delivering her three-year-old son, Henry, says: "I have good memories of my childhood illnesses. It was not a problem. I think children have to go through those illnesses to grow stronger. My doctor agreed. He practises homoeopathy as well as orthodox medicine."

But Judith Illy, 38, delivering four-year-old Camilla, disagrees. Her daughter has had all the vaccinations, on the advice of their family doctor. "He pressed us very strongly to have her vaccinated. When the disease comes the child can die. And if something happened I would not be able to live with myself. It all depends on the doctor."

Wolfgang Peuckert, a kinderarzt - community paediatrician - with an elegant surgery down the road, is worried about the attitude of doctors. Some, he said, seemed to tell parents what they wanted to hear to keep their custom. "It is business," he said. The consequence is outbreaks of measles every two to three years. "Parents say it is good for the child's development. It is not rational. Parents don't understand that these illnesses have complications." Peuckert will only accept children who have been fully vaccinated. But in this he is rare in the Wierhe.

At the Elterninitiative kindergarten, an alternative establishment co-run with the parents next door to St Christopherus, Gabriele Preis, the head teacher, hoists the sweatshirt of a tousle-haired four-year-old to reveal the tell-tale signs of chickenpox on his chest. Four of the kindergarten's 17 children are off with the illness. "Our parents are very against what the health ministry says is necessary for children. They are against all official medicines such as antibiotics."

Rheinhard Berner, a consultant paediatrician at the University Children's hospital, remembers Claudia with her severe encephalitis, and responds to the views of parents with weary resignation. "It is crazy that people should believe their children have to suffer because these illnesses belong to their normal development. We did not expect Claudia to survive. One in 1,000 cases of measles will develop encephalitis. It is true that it is rare, but we think it is right to protect children."