Mrs Bowen, who said Trinity had received her first two monthly doses of DPT without problems, said: "She is our first child and we love her to death. We will do anything we can for her.

"I want an investigation to be opened into this."

Mrs Bowen praised staff at the RD &E for their treatment of Trinity, but added: "We shouldn't have been there in the first place."

Glaxo Wellcome, now part of GlaxoSmithKline, is already being sued by 2,000 families over the controversial triple MMR (measles, mumps, rubella) vaccine.

A spokesman for the drugs company said no group action had been taken against the company so far relating to its DPT jab although he added: "We have been told the Legal Services Commission is considering more than 100 cases.

"There was a test case in 1988 which found no evidence, so I don't know why that doesn't still stand."

Cases lodged with the Legal Services Commission are seeking Legal Aid funding so that people can pursue legal action.

The Department of Health, which recommends the triple vaccine, says no evidence has been produced to link it to epileptic seizures or brain damage. However, the diseases which the vaccine combats are threats to children's health.

Diphtheria is an acute infection of the nose and throat which may prove fatal if not treated early, whooping cough (pertussis) is a highly infectious bacterial disease that settles in the lungs and throat, and tetanus enters via wounds and can prove fatal.

The DPT vaccine is given in three monthly stages. Known potential side effects include pain at the injection site, headache, spasms and vomiting.

As a triple jab, DPT has been around for more than 40 years, although its components have been altered in that time.

Devon consultant in communicable diseases Dr Mark Kealy said there had been controversy over many years regarding the pertussis component of the jab: "There have been views expressed that it has caused brain damage in a very small number of children, although this has never been substantiated.

"If it does cause such problems it is at a very low level of incidence.

"Children do have fits when their temperature rises and it is easier for parents to remember that they have just had a jab and link it to that rather than anything else," he said.

Dr Kealy said he regarded the vaccine as safe.

Exeter-based British Medical Association spokesman Dr Adrian Midgley also said he believed the vaccination was safe. He said: "Seizures in babies are enormously frightening when they are happening and a parent should immediately call 999. By the time an ambulance arrives they will probably have finished convulsing.

"Babies have fits at random times and this can obviously be after they have been immunised. We are alert to this possibility.

"If DPT was causing fits we would expect to see that the proportion of children having fits after having DPT was greater than the proportion otherwise. That is not the case," he said.

A devon mother has spoken of her fear that a combined jab may have caused her six-month-old baby to suffer epileptic seizures.

Just four days after baby Trinity Bowen received her vaccination against diphtheria, whooping cough and tetanus, she suffered a massive convulsion.

Now her parents Mellissa and Simon are hoping their daughter will not be permanently epileptic or suffer from brain damage.

Mrs Bowen, 31, of Park Street, Crediton, said: "I was so scared. She developed meningitis-type symptoms with high fever and a tiny rash on her chest. She was in her cot and she was convulsing in a major way.

"I literally thought: 'She's dying'. My husband was away, so I was on my own. I was going to ring a doctor but I went straight for an ambulance instead.

"She was treated, but she had five more seizures that day and four more after that.

"She could have died. It was extremely frightening.

"The nurse asked if Trinity had received any jabs, but I didn't think much about it at the time."

She has since learnt that 120 families are planning legal action against the vaccine's manufacturer Glaxo Wellcome.

Mrs Bowen said: "Trinity's OK at the moment but she is taking epilepsy medicine and will have a brain scan in a couple of months' time."

She said neither her family nor her husband's had any history of epilepsy.

Mrs Bowen, who said Trinity had received her first two monthly doses of DPT without problems, said: "She is our first child and we love her to death. We will do anything we can for her.

"I want an investigation to be opened into this."

Mrs Bowen praised staff at the RD &E for their treatment of Trinity, but added: "We shouldn't have been there in the first place."

Glaxo Wellcome, now part of GlaxoSmithKline, is already being sued by 2,000 families over the controversial triple MMR (measles, mumps, rubella) vaccine.

A spokesman for the drugs company said no group action had been taken against the company so far relating to its DPT jab although he added: "We have been told the Legal Services Commission is considering more than 100 cases.

"There was a test case in 1988 which found no evidence, so I don't know why that doesn't still stand."

Cases lodged with the Legal Services Commission are seeking Legal Aid funding so that people can pursue legal action.

The Department of Health, which recommends the triple vaccine, says no evidence has been produced to link it to epileptic seizures or brain damage. However, the diseases which the vaccine combats are threats to children's health.

Diphtheria is an acute infection of the nose and throat which may prove fatal if not treated early, whooping cough (pertussis) is a highly infectious bacterial disease that settles in the lungs and throat, and tetanus enters via wounds and can prove fatal.

The DPT vaccine is given in three monthly stages. Known potential side effects include pain at the injection site, headache, spasms and vomiting.

As a triple jab, DPT has been around for more than 40 years, although its components have been altered in that time.

Devon consultant in communicable diseases Dr Mark Kealy said there had been controversy over many years regarding the pertussis component of the jab: "There have been views expressed that it has caused brain damage in a very small number of children, although this has never been substantiated.

"If it does cause such problems it is at a very low level of incidence.

"Children do have fits when their temperature rises and it is easier for parents to remember that they have just had a jab and link it to that rather than anything else," he said.

Dr Kealy said he regarded the vaccine as safe.

Exeter-based British Medical Association spokesman Dr Adrian Midgley also said he believed the vaccination was safe. He said: "Seizures in babies are enormously frightening when they are happening and a parent should immediately call 999. By the time an ambulance arrives they will probably have finished convulsing.

"Babies have fits at random times and this can obviously be after they have been immunised. We are alert to this possibility.

"If DPT was causing fits we would expect to see that the proportion of children having fits after having DPT was greater than the proportion otherwise. That is not the case," he said.