SINGAPORE - He has a disease so rare, only one child in 250,000 gets it.
And it is a condition so severe that Stephen Oon's family had to isolate themselves from the rest of the world to reduce the chances of him getting an infection.
In May 2010, when little Stephen was just two months old, he was diagnosed with Chronic Granulomatous Disease (CGD), a hereditary disease that affects the immune system.
CGD left him susceptible to most common bacteria and fungi found around us, his body defenceless against them.
Even the standard BCG vaccine given to him at birth landed him in the operating theatre.
A poorly-maintained air conditioner left him with a lung infection that took the boy six months to recover from.
Today, however, four-year-old Stephen looks like any other healthy child.
A haematopoietic stem cell transplant has given his body the ability to fight against common infections.
And, for the first time, the Oon family can enjoy the simple pleasures of being outside their home without worry.
But life was not always so simple.
Mr Daniel Oon, 36, told The New Paper how his world was turned upside down when he first learnt of his son's condition.
As doctors told Mr Oon and his wife, Karen, of the level of hygiene it would take to keep their boy safe, the Oons realised they had to radically change their lifestyle.
Dettol like water
Dettol like water
Just to be around Stephen, they had to wash their hands with anti-microbial soap 30 to 40 times a day.
Strong disinfectants were used to clean every surface in their home.
"We used Dettol like it was water," Mr Oon, a sales engineer, said.
His wife added: "We would clean the chair Stephen sat on or anything he touched. People thought we had OCD (obsessive-compulsive disorder)."
The family started to isolate themselves after Stephen developed a fungal lung infection in 2011.
It was caused by aspergillus, a mould commonly found in poorly maintained air conditioners.
That was when the Oons realised how vulnerable their son was.
They bought hospital-grade air purifiers and kept Stephen inside the home, becoming even more particular about their hygiene protocols.
They could not risk falling sick and spreading it to their boy, so Stephen's parents went out less, in a bid to reduce the chances of bringing back illnesses.
"In a way, we started to withdraw from the outside world," Mr Oon said.
Doctors told the family that the only cure for Stephen was to get a haematopoietic stem cell transplant.
But the procedure was a risky one as Stephen's immune system had to be completely shut down.
Three out of 10 don't make it past the transplant, the Oons were told.
But they took their chances anyway.
Neither Stephen's parents nor his two sisters were suitable donors. He is the middle one of three children.
But the family found a suitable stem cell sample from an unrelated donor through the Singapore Cord Blood Bank in late 2010.
Their joy, however, was short-lived.
His transplant, initially scheduled for early 2011, had to be pushed back after Stephen reacted badly to his BCG vaccine.
He needed to be infection-free as any lingering bacteria or fungi could wreak havoc once his bone marrow stopped functioning.
The next three years would be an emotional roller coaster for his parents as Stephen developed new infections, going in and out of the hospital more than 10 times, forcing his transplant to be postponed time and again.
The family's finances also took a major hit.
Mrs Oon had to take more than three years of unpaid leave from her teaching job to become Stephen's full-time caregiver, leaving Mr Oon the sole breadwinner.
At one point, Stephen's drugs, consultations and medical supplies such as disinfectant and gauze cost over $700 per day, Mr Oon said.
And this was even after Mr Oon had applied to Medifund, which helped sponsor Stephen's $650 a day anti-fungal drugs.
In January last year, doctors finally decided that Stephen was healthy enough to undergo his transplant.
Even then, things were not to be easy.
Mrs Oon had to live in the hospital for more than four months caring for Stephen at the transplant ward in KK Women's and Children's Hospital.
The transplant was a success and Stephen started to produce white blood cells in about two weeks.
But for another three months, he had to fight off repressed infections which could destroy his fragile immune system.
Mrs Oon could not step out of the 6m by 4m hospital ward.
Her husband and two daughters - the youngest then just two months old - were not allowed in. They were separated by glass windows.
"It was like prison but worse," she said. "For Stephen, it meant being away from his only two friends in the world - his sisters."
The hardest part of the ordeal was the limits it placed on her son, Mrs Oon said, adding that it's not normal for a young child to spend his day cooped up at home.
Before his recovery, Stephen had never been to the park or the beach, and barely saw the outside world.
Mrs Oon said: "It is the little things we take for granted.
"Just travelling in his father's car would get him excited as it gave him a rare glimpse of the outdoors."
After his discharge in May last year, Stephen has been slowly introduced to the outside world.
One year on, Stephen is going to a child care centre.
While his immunity has improved, the Oons are taking no chances and are still very careful about hygiene.
Looking on as his boy ran around the playground, Mr Oon said: "We never imagined that this was possible."
Boys more susceptible
Boys more susceptible
Chronic Granulomatous Disease (CGD) is very rare, Associate Professor Chan Mei Yoke told The New Paper.
The Head of Haematology and Oncology at KK Women's and Children's Hospital said the disease is an inherited condition and boys are more likely to be affected.
Those afflicted with the disease have defective immune systems and are unable to kill certain types of bacteria and fungi.
Prof Chan said patients with CGD have recurrent and chronic infections like skin abscesses.
Therefore, they need to be very careful about hygiene, she added.
Infections have to be treated immediately and drugs are prescribed to prevent them.
But Prof Chan said the only cure for CGD is to get a new immune system by undergoing a haematopoietic stem cell transplant.
In such a transplant, bone marrow stem cells, where the immune system cells originate from, are destroyed using chemotherapy.
Normal stem cells are then transplanted.
If the transplant is successful, the normal stem cells will re-populate the "empty" bone marrow and start to produce normal immune system cells like regular white blood cells.
Most stem cell donors not family
Like Stephen, the majority of patients who need blood stem cells turn to unrelated donors.
Only about three in 10 patients find a match in their family, said Dr William Hwang, medical director of the Singapore Cord Blood Bank (SCBB).
Blood stem cells help produce white blood cells to fight infection, red blood cells to carry oxygen and platelets for clotting.
Used to treat blood disorders like leukaemia, immune deficiencies and metabolic diseases, stem cells are found in bone marrow and peripheral blood circulating around the body.
They are also found in the umbilical cord and placenta.
Cord blood is collected after child birth - when the umbilical cord is clamped and cut, blood is taken from the section attached to the placenta.
Associate Professor Chan Mei Yoke said that compared to other sources of stem cells, cord blood is less exposed to infectious agents.
It is also easier to transplant stem cells using mismatched cord blood, the Head of Haematology and Oncology at KK Women's and Children's Hospital (KKH) added.
Dr Hwang of SCBB said that cord blood is also readily available, unlike bone marrow or peripheral blood, where potential donors may back out.
One public bank
One public bank
But it is limited by the amount of stem cells that can be harvested, he said.
There are four cord blood banks in Singapore and SCBB is the only public one.
Cord blood donated to the bank is available for any patient who requires it, in Singapore and around the world.
SCBB also maintains a public registry so that doctors can search for matches.
In contrast, private cord blood banks charge a fee to store cord blood, which is accessible only to the donor's family.
Since its establishment in 2005, SCBB has received more than 26,000 donations. Due to stringent requirements, not all of the blood donated is stored.
It has more than 10,000 cord blood units available for stem cell transplants.
The SCBB was recently accredited by the Foundation for the Accreditation of Cellular Therapy. This is the highest standard for cord blood banks, Dr Hwang said.
"(The accreditation) offers assurance to transplant centres that SCBB's cord blood units would give their patients the best chance for survival," he said.
This article was first published on June 2, 2014. Get The New Paper for more stories.