Sick and cold. That is how I felt. Also completely exhausted, as though someone had taken the bones out of my body. I had gone to bed the previous night a normal, healthy 40-year-old woman only to wake up feeling dreadful. Four days later I was in intensive care having been diagnosed with one of the world’s rarest diseases: a life-threatening blood disorder called atypical haemolytic uraemic syndrome (aHUS) that had caused acute kidney failure.

As I come to terms with this medical car crash, I want to share my experience to help to raise awareness about ultra-rare conditions such as mine and to say thank you to the NHS doctors, nurses and laboratory technicians who saved my life.

It was January 17 and I had a busy day planned so there was no time for being ill. Suppressing the urge to vomit, I heaved myself out of bed and herded my two eldest children into their clothes before making them breakfast and putting myself in the shower.

Fortunately my youngest child, a baby boy, was at my mum’s that week, leaving me with one less person to deal with. So after the other two were packed off to school and preschool, I did a telephone interview with a contact and then walked to the station because I needed to be in London to attend a press conference.

The press conference was a mistake. I was feeling really grim, shivered uncontrollably throughout, struggled to concentrate and only just managed to make it back home. Stumbling into my bedroom, I sank into bed fully clothed, including my winter coat, but still shivered even under the duvet.

That night I was repeatedly sick. I could not eat. I could barely drink. Norovirus, I self-diagnosed. The next morning I felt no better, although I managed to force myself to eat a banana and some toast. I just about had the strength to help our au pair to put my elder son and my daughter to bed in the evening, before collapsing back into mine, only leaving it to vomit.

Thursday was a blur of nausea and sleep. My dad came round to help with the children. I lay hidden in bed, unable to move. By this point I had pretty much stopped needing to go to the toilet, but instead of being alarmed at losing the ability to urinate I felt quite pleased because it was one less thing to have to move for.

I had weird half-dreams about needing help. I woke at dawn thinking that I should do something, but was worried about wasting a doctor’s time if I showed up at my GP’s surgery or accident and emergency complaining simply about feeling sick. Thankfully, something inside me fretted that this was not “normal sick”. My husband, who was abroad on business, agreed. So I texted a friend, Amy, to ask her to take me to A&E at Pembury hospital in Tunbridge Wells. When she came over, the first thing she said was: “Debs, you’ve turned yellow.”

Walking into the hospital reception I had to stutter past the front desk and into the nearest toilet to be sick again. My symptoms — feeling unwell — did not trigger any alarm bells in the triage nurse, so I sat in the waiting room for a couple of hours before being seen by the duty GP at the minor injuries unit. She said I needed blood tests, which were quickly taken.

When the results came back a junior A&E doctor ushered me into a treatment room. I half-expected him to say everything was normal and send me home, so the words “Your bloods are deranged and you have acute renal failure” took a moment to register.

The doctor gently explained that my platelets — the cells in your blood that prevent clotting — were very low, as was my red blood cell count. Perhaps fortunately for me, in my sick state, I had forgotten what renal meant, so the fact that my kidneys were also failing did not cause alarm. That came later.

I called my dad to ask him to come with an overnight bag because it did not look as if I would be allowed home any time soon. The hospital’s medical team took over and set about finding out what was making me so ill. Another junior doctor sat with me talking through my medical history for clues.

I wondered whether a previous case of Q fever, a tropical disease that I caught while covering the 2011 conflict in Libya, had anything to do with my deranged blood. I even half-jokingly asked whether I had been poisoned by the Kremlin, which has a habit of targeting journalists.

A haematologist at nearby Maidstone hospital was alerted. She knew of a world-renowned blood expert called Dr Marie Scully at University College London Hospitals. This consultant contacted Scully to ask her opinion on my case. Despite the lateness of the hour — it was well into Friday evening by then — Scully called back. She diagnosed me with TTP, another life-threatening blood disorder that requires immediate treatment, and said I was to be blue-lighted to University College Hospital.

When informed of this development I made the mistake of googling TTP on my phone. The results were alarming and included a statistic that 90 per cent of sufferers die if untreated. That’s OK, I told myself. I was going to receive treatment.

A creeping fear took hold as I travelled in the ambulance. I contemplated whether I would die. How would my husband and children cope? Would I see them again? The ambulance crew were fantastic. One of the two paramedics sat in the back with me and my dad, making funny small talk, which helped to stop the tears.

At UCH I was wheeled into a room in intensive care. A doctor called Ned appeared. By now it was the early hours of Saturday. He told me that he was going to put a line into my neck and another line into a femoral artery. Over the next few hours I was hooked up to a machine via the tube coming out of my neck. It sucked the blood out of my body, separated all the plasma from it, mixed in bags of donor plasma and pumped the new concoction back into me. At the other end of my body the line out of my left thigh was hooked up to a dialysis machine that was helping to clean up my kidneys.

By the morning a nasty headache had developed, requiring increasing strengths of pain relief. I was also being infused with a variety of anti-nausea medicines because I still felt very sick. In addition, a drip to stop me from being so dehydrated — I was finding it hard to drink because of the nausea — was attached to one of the many lines coming out of me, while a tube that provided additional oxygen clung to my nostrils.

It was all pretty overwhelming until a woman with a friendly face walked into the room and informed me in a very matter-of-fact manner that I was going to be fine. This was Dr Scully.

She no longer thought I had TTP, but instead said I had aHUS. Neither condition meant much at the time because I was still searching for reassurance that I had not become the latest victim of a Russian poisoning plot. Alexander Litvinenko had been treated at the same intensive care unit.

The fact that my kidneys were failing did not cause alarm

An intensive care consultant who was doing the rounds with Scully stepped forward. Professor Mervyn Singer had been working when the dissident Russian spy was admitted to the hospital in October 2006, dying from radiation poisoning. “I assure you that you have not been poisoned,” he said with a smile, echoing the same confidence as Dr Scully that I had aHUS and would make a full recovery. It felt good to be told that I would get better, although I could not imagine how because I still felt so poorly.

It was not until later that day when blood tests showed that my platelets were starting to pick up that I began to believe this was not the end, although my husband maintains it was his appearance at my bedside the next evening that was the turning point.

Over the next five days I was given five plasma exchanges and taken off the dialysis to see if my kidneys would work on their own — thankfully they did (touch wood; I have touched a lot of wood over the past month). I also learnt more about aHUS. The disease is caused by a part of the body’s immune system attacking the blood cells. Small clots are then created in the filters inside your kidneys, making them fail. Other organs can also be affected.

In the past the prognosis for aHUS was dire; a quarter of sufferers died and half experienced end-stage renal failure, requiring a lifetime of dialysis. Since 2013, however, patients in the UK have had access to a drug called eculizumab, which effectively turns off the part of the immune system that is causing the problem. The drug is expensive — I’ve dubbed it “liquid gold” because it is more than £10,000 a shot — but it saves lives. Mine, for one, has been given back to me. A truly humbling concept.

After ten days in hospital I was discharged. I initially had a weekly injection of eculizumab. After five weeks I started fortnightly infusions. They will continue for as long as the doctors deem it necessary. I am hoping this will be a matter of weeks or months. For some people it is for years.

It still feels as though I am balancing on a tightrope and could fall off at any moment, but it is important to remember that I am one of the lucky few. My condition was quickly diagnosed before irreversible damage could be inflicted on my kidneys, and I live in a country that can afford to give me the cure. This is not the case in much of the rest of the world.

As a result I am able to hold my children again. I am slowly returning to work. I am alive.

Today is Rare Disease Day, rarediseaseday.org; more can be found out about aHUS at ahusuk.org

The one in 2.5 million disease

• Atypical haemolytic uraemic syndrome (aHUS) is a disease involving a part of the immune system called the complement. The complement system suddenly starts attacking a person’s own cells. This causes small blood clots to form in the area of the kidney that filters blood. Red blood cells are also broken up. It is most commonly caused by a genetic mutation that can be triggered by a number of external factors, including infection and pregnancy.

• aHUS affects one in 2.5 million people in England. NHS England expects to see about 20 new cases a year. Of 150 or so patients receiving a special drug to treat aHUS in England, almost a quarter are children. Of the remaining group, 65 per cent are female.

• The symptoms of aHUS include the following: a patient will often be pale and tired; they may have bleeding, such as a nose bleed; there will be signs of kidney failure, which include a decreased urine output, vomiting, swelling of the body, and breathing difficulty; and they may experience headaches or fits.

Statistics: National Renal Complement Therapeutics Centre, Newcastle