By Thomas Moore, Health and Science Correspondent
The World Health Organisation (WHO) has admitted that it botched attempts to halt the ebola outbreak in West Africa.
The UN health agency has blamed factors including incompetent staff and a lack of information, according to a draft internal document obtained by The Associated Press.
"Nearly everyone involved in the outbreak response failed to see some fairly plain writing on the wall," the document says.
WHO admits it was "particularly alarming" that the head of its Guinea office refused to help get visas for an expert ebola team.
The organisation concedes it should have realised that traditional containment methods would not work in a region with porous borders and broken health systems.
Another factor was "politically motivated appointments" to WHO country offices in Africa.
Sky News Health and Science Correspondent Thomas Moore believes "simple infection control" would have stopped the virus spreading.
Here he takes a look at the mistakes that have contributed to a crisis that has killed at least 4,555 of the 9,216 people infected so far.
:: THE EPIDEMIC SMOULDERS
The epidemic started almost 10 months ago with the death in Guinea of a two-year-old boy called Emile.
For three months, the outbreak smouldered. Cases here and there, the virus spreading into neighbouring Sierra Leone and Liberia.
The cases were in rural areas, far from medical help; the deaths undiagnosed and unrecorded.
But then, suddenly, it flared up. The Health Ministry in Guinea reported a mysterious illness with a high fatality rate.
By the time ebola had been identified as the cause, there were 86 cases and 59 deaths in four districts of Guinea.
:: THE FIRST MISTAKE
By the end of March it had come to the attention of the World Health Organisation.
A team of ebola experts from the WHO and the US Centers for Disease Control reached the area.
Within weeks, cases dwindled and the medics moved on.
It was assumed it was just another rural outbreak, easily contained, just as the previous dozen or more outbreaks had been in Central Africa.
That was the first big mistake. The virus had already spread too far.
:: THE SECOND MISTAKE
Between the end of May and late July the virus reached the capitals of the three countries.
It was the first time that ebola cases had ever been reported in densely populated cities.
Eradication now became far more challenging - it would be impossible to quarantine an entire capital.
Even though there were still only just over 1,000 cases, the seeds had been sown for an exponential rise in numbers.
Still, there was no international response.
:: THE THIRD MISTAKE
By now it was clear the health services in the three countries could not cope.
Years of civil war had left the countries on their knees.
Liberia had just 120 doctors to care for four million people.
There simply weren't enough doctors to quarantine infected patients and chase down their contacts.
But still it was only charities and missionary groups that were sending in medical teams and organising clinics.
:: THE FOURTH MISTAKE
All three countries were too slow to tackle risky cultural practices, the suspicion of health workers and the stigma of the disease.
Relatives washed the dead with their bare hands, putting themselves at risk.
Bodies were hidden by relatives for fear of being ostracised by the community.
And villagers chased away medical teams, believing they were spreading the virus.
Yet it was only in August that Sierra Leone's government began an awareness campaign to change attitudes.
:: THE FIFTH MISTAKE
It wasn't until September that world leaders really understood how serious the epidemic had become.
A cynic might say it was the repatriation of western health workers - and then the arrival of infected travellers - that was the game-changer.
The US has begun building 1,700 beds in Liberia, the UK is building 700 in Sierra Leone and France is co-ordinating efforts in Guinea.
But it's nowhere near enough. The WHO still has only a fraction of the resources it needs.
And, with every week of delay, the virus spreads further. Cases are doubling every month.
That means more beds, more medics and more money will be needed.
It's no wonder the WHO says the ebola epidemic has been a wake-up call for the world.
