BBC News, Plymouth
Archie Barton's arrival nearly two years ago can only be described as an unexpected surprise for his parents Nicky, 41, and Murray, 44.
Archie was rushed to hospital in June 2007
With two children already aged 15 and 19 they thought their family was complete.
But then Archie arrived and they felt like seasoned parents ready to tackle parenthood for a third time.
So when he was developed a temperature on 11 June his mother put it down to the fact he was teething.
But less than 12 hours later Archie was in hospital fighting for his life having been diagnosed with meningitis B, and meningococcal septicaemia was already beginning to take its toll on his tiny body.
Symptoms include fever, headache, irritability, lethargy, poor feeding, drowsiness or seizures.
Older children may complain of severe headaches, a dislike of bright light or noise, and neck stiffness.
An unusual rash which does not blanche when pressed may be a sign of meningococcal infection.
The months that followed were what his mother calls a "complete nightmare".
"It's not like anything I can describe," said Nicky - who did not return to her Plymouth home for five months from the night Archie was taken to hospital.
"It is just the cruellest of illnesses," she said.
As the septicaemia took hold Archie had to have both of his legs removed above the knee and lost a number of fingers on each hand and the tip of his nose, as well as part of one of his ears.
Retinal haemorrhages have also caused severe visual impairment.
He has already had to endure numerous skin grafts and faces many more operations in the future.
Nicky says, at times, it is difficult to remember the child he was before.
"I have pictures of him on the beach in Cyprus just days before he got ill," said Nicky.
"But I can't bring myself to look at them yet. I think perhaps I am still in shock."
There is currently no vaccine against the meningococcal strain of the disease and in April Meningitis UK, a Bristol-based charity, launched a £7m vaccination appeal.
The charity says meningococcal group B, which causes both meningitis and septicaemia, accounts for almost 90% of all the 2,500 cases of the illness in the UK each year.
Archie faces many more operations in the future
"A number of research teams have developed vaccine candidates, some of which look quite promising," said Steve Dayman, the charity's chief executive.
"But there's still a great deal of work to be done."
In the meantime he says awareness of symptoms and prompt treatment remain the greatest weapon.
A spokeswoman for the Department of Health said: "Protecting children against meningitis and the development of a Meningococcal Group B vaccine to protect against another form of meningitis is important.
"The Health Protection Agency is embarking on studies on trial MenB vaccines."
She added that the UK was the first country in the world to introduce the current meningitis C vaccine and the introduction of the pneumococcal vaccine, in September 2006, protects children against another major cause of meningitis.
Archie returned home from hospital on 26 October and the family is now in the process of setting up a website to start fund-raising for Archie's future care and in anticipation of paying for the prosthetic limbs he will need.
"We've heard that some NHS prosthetics, especially for above the knee amputations are not that good and so legs for Archie could potentially cost up to £12,000 a pair and he could need up to four pairs a year," said Nicky.
She and Murray also want the website to help raise awareness of the illness and its devastating effects.
"I just had no idea that this illness could do this to a child," said Nicky.
And apart from the physical effects what it has done is to transform her happy, confident 18-month-old - who was beginning to walk and talk - into a fretful child wary of strangers and in need of constant reassurance.
"It's like having a new baby all over again," she said.
The practical consequences of suddenly having a child with so many special needs is also something the whole family is trying to get used to.
Archie spent five months in hospital
Archie now requires his own diary to keep track of all his appointments and there is no question of Nicky returning to work.
"Luckily we are a close family and I think that is going to help us," said Nicky.
"But this Christmas is going to be very different for all of us.
"Sometimes I just have to remind myself how far Archie has come since June," she said.
"I am so looking forward to the 1st of January 2008 so we can start to try to put 2007 behind us."