The Ebola outbreak in west Africa is already a crisis; it could very easily become a catastrophe.

Dr Ian Norton, chief of foreign medical teams with the World Health Organisation (WHO), tells the ABC about the race against time to build a number of massive field hospitals in Monrovia, Liberia, as the death toll nears 3,000.

We have only a narrow window of opportunity in which to contain this outbreak.

If we ignore it, we will find the disease much more difficult to control and can expect infection rates to escalate.

Not to put too fine a point on it: we have a closing window of perhaps weeks now before we will not be able to manage all the cases on the ground in the way that we normally would.

Already the WHO and the ministries of health of the three most affected countries are thinking of other ways to contain and manage the large numbers infected.

This is new for everybody. The only team that has built a field hospital for Ebola treatment before has been from Medecins Sans Frontieres (MSF), and their standard operations are for only 40 people.

We are building five 100-bed field hospitals in Monrovia, in addition to the 200-bed facility which already exists there and which will soon be expanded to at least 300, perhaps 400, beds.

We are calling for foreign medical teams across the world to come and assist us.

We are not looking for huge numbers of foreign doctors and nurses and logistics staff but at least a core group of 30 to 40 who would help manage these large centres and then work alongside national medical staff and nurses.

Tragically, Liberia – which already ranks fourth-last in the world for numbers of doctors per population – has lost almost 20 doctors to Ebola. They only produce 10 doctors per year in a medical class.

They have also lost a large number of nurses, and Ebola care is all about the nursing care. There are only a couple of thousand nurses in the country and we know that at least 90 have died from the infection and another 50 or 60 have survived.

The nurses and doctors are actually willing to come back to work, with measures in place to assist them including protecting equipment, training and a payment scheme which reflects the danger of the work.

Without medical care, the mortality rate of this Ebola outbreak is about 90 per cent. While it is a devastating disease, it is not universally fatal, even with minimal care.

But with better care, and certainly with the new Ebola treatment centres and with the right number of staff treating them, we can gradually escalate the level of care and have better outcomes.

For example, we have seen in Guinea for several months that with good supportive care we can bring the mortality rate down to 30 to 50 per cent at most.

So we can see a several-fold improvement in survival if we can just get the teams in here and get these Ebola treatment centres up and running.

We have to stop this spreading beyond the point of no return.

This interview with Dr Ian Norton first aired on the ABC’s PM program.