When little Harry Attryde developed a rash on his leg, his dad thought it could be chicken pox.

But a day later the youngster became more unwell and was rushed to hospital with suspected meningitis.

Doctors told the family to prepare for the worst and his mother, Sally, was advised to fly back from a business trip in Chicago to be at her son's side.

Now 17 months old, Harry seems to have recovered from the experience, but his family are keen to raise awareness about meningitis.

Dad Nik will run the London Marathon next year for the Downend-based Meningitis UK, to help it fund research to develop a vaccine against the disease.

Mr Attryde, 46, noticed a rash on Harry's leg, which looked like chicken pox when he woke up one morning in March. The youngster had a temperature of 40 degrees, so his dad contacted the doctor, who advised that he keep an eye on him.

The next morning Mr Attryde, a strategic development manager for NHS Bristol, found his son listless and unresponsive. He also had some small dark spots on his leg, which looked completely different to the previous rash. He rushed Harry to the doctor again, who immediately suspected meningitis.

Mr Attryde said: "Meningitis was something I didn't want to think about. But on the way to hospital Harry went downhill very rapidly. He was injected with a shot of steroids and high-strength antibiotics at the child accident and emergency unit as staff there tried to stabilise him.

"The consultant said the next 12 hours would be critical and that my wife had to come back from Chicago. It was every parent's worst nightmare.

"I couldn't actually talk to Sally because I was in shock. The consultant spoke to her and asked her to come home straight away."

Mrs Attryde, a financial controller, got on a plane with a colleague and it was not until she was in a car on the M4 that she called for an update.

Luckily Harry showed signs of improvement. A lumber puncture – where a needle is inserted into the back to collect spinal fluid – confirmed the youngster had meningococcal meningitis and septicaemia, which is caused when the meningitis B bacteria enter the blood stream and multiply uncontrollably, poisoning the blood and completely overwhelming the immune system.

After a week on antibiotics he was allowed home.

The family cannot be certain that he is completely over the experience yet, but he is doing well.

The couple, who also have a three-year-old daughter, Alex, are encouraging people to be aware of meningitis as the colder weather makes it more prevalent.

Mr Attryde said: "Harry might initially have had chicken pox, we'll never know, but he also had some classic meningitis symptoms – a rash on his leg, high temperature and was very listless. The symptoms are different with everyone but parents need to be armed with the knowledge in order to act as quickly as possible."

"Harry is absolutely fine. He has had his hearing tested and it was clear and there have not been any problems in his development and they are confident he has not been affected."

Mr Attryde has completed half marathons in the past but said he is not much of a runner, so the 26-mile course will prove quite a challenge.

He said: "I never thought about doing a marathon and never really wanted to but I wanted to do something to raise awareness about meningitis and also to challenge myself at the same time."

Classic symptoms of meningitis are a headache, stiff neck and a dislike of bright light but can also include difficulty supporting own weight, fever, vomiting and diarrhoea, confusion and drowsiness.

Symptoms of meningococcal septicaemia include aching limbs, cold hands and feet and a rash which starts like pin prick marks and develops rapidly into purple bruising.

Not everyone gets all the symptoms, and they can appear in any order. As the disease can kill within hours, swift treatment is vital as delays could lead to death or survivors being left with disabling after-effects.

To order a free symptoms information pack or for more information about Meningitis UK, call 0117 373 7373 or visit www.meningitisUK.org.

To sponsor Nik in the marathon, go to www.justgiving.com/Nik-Attryde.