Auckland parents Ian and Linda Williams thought they had made an informed choice not to vaccinate their children, but after their son ended up in intensive care with a tetanus infection they realised they had made a terrible mistake.

"The mistake that we made was that we underestimated the diseases and we totally over-estimated the adverse reactions", says father Ian Williams, who is speaking publicly of his family's ordeal in an effort to warn other parents about the dangers of not immunising their children.

Minor cut, major infection

It started when seven-year-old Alijah got a small cut on the bottom of his foot in December 2012.

"Of course we didn't think it was too serious, it was just a little cut but a couple of days later he started getting symptoms like a stroke on the side of his face," Mr Williams says.

"A couple of days later during the night he started to get cramps across his face. His face would contort and he was in a lot of pain."

After 24 hours in Auckland's Starship Children's hospital, the doctors diagnosed Alijah with tetanus, and he was taken to intensive care.

Mr Williams recalls his son's agony, "It's a terrible thing... Your whole body arches, your arms go up in the air."

"It's like getting cramp but it's everywhere, across the face as well. They are so tight your jaw locks."

"The tetanus bacterium makes a toxin that attacks the nerves."

"It got so bad they put him in an induced coma just to put him out of his misery."

Ian and his wife were asked to leave the room as doctors cut a hole in Alijah's throat so a life support tube could be inserted, and Alijah was heavily sedated for the next three weeks to allow his body to heal.

"We felt terrible."

"He was in such pain due to us and our decision-making process so that's why we went to the papers in New Zealand - we just wanted to get our experience out there."

"It was very obvious we had made a mistake."

Deciding not to vaccinate

As well as Alijah, the Williams have a nine-year-old son and a two-year-old daughter, and Ian Williamson says they did their own research and decided not to vaccinate their children.

"My wife was very against it for her own reasons," he says.

"I have a science degree and my wife since then has got a science degree as a midwife. I was open to both ideas so I looked into it.

"If you google vaccines you get a lot of pros and a lot of cons, and you start to read all the cons and they start to weigh on you and you start to believe all the things that are said.

"It looks like a fifty-fifty argument."

Williams says that he was influenced by stories he read on the internet that the MMR (Measles, mumps and rubella) vaccine was linked to children developing autism; that they contain mercury and aluminium and that vaccines are promoted by drug companies purely for profit.

"There are a number of myths out there, and it's really easy to get sucked in."

"As soon as they said it was tetanus my other two kids were vaccinated the very next day, against all childhood diseases."

Speaking out

The Williams' also took the unusual step of going public about what had happened to Alijah.

Ian Williams says he wants to help other parents who he thinks may be as overwhelmed as he was by the conflicting information about vaccines that is published online.

"No one wants to hurt their kids; we didn't want to hurt our kid of course.

"The main research that you should do as a parent when you're looking at vaccination, the easiest and the clearest thing you could do would be to survey doctors and ask them if they are pro or anti vaccines.

"What you will find is that almost all of them are. Then ask yourself the question, why is that?

"Once you see one of these diseases, they are terrible. Children die from these diseases."

"The mistake that we made was that we underestimated the diseases and we totally over-estimated the adverse reactions [to vaccines]"

Huge response

Despite the often highly-charged and polarised debate around childhood immunisations, Ian Williams says he's been happy to speak out and that the response to Alijah's story has been very positive.

"We've had a very big reaction in New Zealand. Alijah was on the front page of two of our biggest papers and doctors have been putting up his picture in their rooms and say families have been coming in and getting their kids vaccinated.

"There has actually been a small percentage increase in New Zealand's vaccination rates [since the story was published in January].

"That's why we did it. I'm happy to be the poster boy for vaccination."

Six months on, Alijah is recovering well.

"After three weeks in intensive care he gradually came out of it," Williams says.

"They gave him less and less drugs and his nerves started to heal."

When he came out of his heavy sedation, Alijah had to learn to walk and eat again.

"He's fine now and all you can see now is some scarring on his throat from the tracheotomy, he'll probably have that his whole life.

"It's a small price to pay. Ten per cent of all people with tetanus die."

What is tetanus?

Tetanus is caused by bacteria which are present in soils, dust and manure. The bacteria can enter the body through a wound which may be as small as a pin prick. Tetanus cannot be passed from person to person.

Tetanus is a potentially fatal disease which attacks the nervous system. It causes muscle spasms first felt in the neck and jaw muscles. Tetanus can lead to breathing difficulties, painful convulsions and abnormal heart rhythms.

Because of the effective immunisation, tetanus is now rare in Australia, but it still occurs in adults who have never been immunised against the disease or who have not had their booster vaccines.

Tetanus vaccines are offered to free infants at 2, 4 and 6 months of age, and again at age 4 years of age and in year 8 of secondary school.

Source: WA Health Department