Public health experts have consistently warned that the novel coronavirus outbreak presents a unique public health threat to the African continent.

The World Health Organization says that only eight countries are ready to deal with the outbreak. Up until recently, most have lacked any diagnostic capability and few countries on the continent have sufficient health systems to deal with severe cases on a large scale.

Despite operating multiple direct flights to coronavirus-hit China, there were no confirmed cases of the novel coronavirus in Sub-Saharan Africa until last week.

That is when Dr. John Nkengasong, Director of the Africa Centres for Disease Control and Prevention (Africa CDC), received a phone call in the early hours of the morning from Nigeria, where an Italian traveling on business was rapidly diagnosed and isolated.

Nkengasong, a former senior official of the US CDC, and his colleagues have been working on a diagnostics and containment strategy to combat the disease.

Nkengasong spoke to CNN about the risk posed by coronavirus to African countries.

This interview has been lightly edited for clarity.

CNN: Nigeria faced a stiff test and it seems, at this stage, that they passed. What is the danger facing Africa now with the novel coronavirus?

Nkengasong: I think there are two dangers facing Africa now -- the first is our ability to detect quickly, and the second is the ability to contain it. Nigeria was able to detect the virus quickly, I would say. The coming days will tell us if the containment strategy is right. The contacts of an individual who tests positive must be isolated and their contacts traced quickly.

Why is speed so important in diagnostics?

Speed is so important in diagnostics because it allows you to isolate the people that are positive and keep them and monitor them for at least two weeks. If you do not pick up these people early, they will keep on mingling in the population and then they keep transmitting the virus to the population.

Before this outbreak, you had to send samples to just two labs from across the continent. What has changed?

Just three weeks ago, South Africa and Senegal were the only two countries on the continent that were doing the testing. But we have ramped up training very quickly ... and as we speak today there are over 40 countries that have the ability to detect the virus.

Africa is a very diverse place. But why are some countries in Africa very susceptible to this particular disease?

Early on -- particularly at the start of this outbreak -- there were certain countries that had direct flights with China. That is Egypt, Morocco, Algeria, Ethiopia, Kenya, Mauritius and South Africa. Those were the first countries with high risk, and most of those countries stopped flying to China. But Ethiopian Airlines is still continuing, though they have reduced to two flights a day going to China.

Then you have the big countries like Nigeria. They don't have direct flights, but they have many people going from there to China. Then you have countries like the Democratic Republic of Congo -- it is a large country and we have a current Ebola outbreak and conflict there. Countries like the DRC have fragile systems, and they are very, very vulnerable without rapid detection and containment.

Some are saying that this virus is relatively mild for most people. But why, particularly in Africa, should people be concerned about the impact that it could have?

We have learned a lot by what is happening in China. The first is the spread of the virus, how quickly the virus spreads there. So even if it is mild, it infects so many people, and the mortality rate is at two percent. That is a large number of people.

But in Africa, why is that particular type of disease dangerous?

It is dangerous for several reasons. Our health systems are not strong enough to provide those respiratory support systems that are required to care for patients that are infected, as we have seen in China.

There are very few countries in Africa with those systems in place in their hospitals to care for a large number of patients. They may be able to care for some patients, but not for a large number of patients if they are overwhelmed, like we are seeing in China.

So it is clearly important to really stop this virus in its tracks everywhere, but particularly in Africa. If we cannot do that, what is the scenario for health systems?

We have to. We don't have a choice, we have to scale our ability to train many people on infection prevention and control, to enhance the screening at our points of entry as quickly as possible to cascade the diagnostics into the country so that our strategy continues to be rapid detection and rapid containment.

Because there is no way our health systems will be rapidly improved to be able to cope with a large outbreak, like we are seeing in China.

If you see community transmission in countries like Nigeria and other African countries, should borders close?

If we are beginning to see community transmission [in which people are infected with the virus in an area, including some who aren't sure how or where they became infected] -- which is the scenario that we truly don't want to see happen -- that will ensure a transmission that becomes very difficult to contain.

At that point we can't talk anymore about a containment strategy, we move to a mitigation strategy. What can we do to mitigate the effect on the community? That will require that we start closing down places of mass gathering -- churches, schools, public facilities. And that will have a severe economic and social impact on the continent. That will be the only way to contain that kind of community transmission through social distancing.

So, we really hope that the strategy for the continent will continue to be rapid detection and rapid containment.

Why have there been so few cases in Africa? Are cases being missed?

There is still the possibility that we have cases and they are not being detected. Time will tell as we expand diagnostics. Remember when this outbreak started, we had the Chinese New Year festival going on and many of the Chinese were in China -- so their movement was not coming into Africa.

But we don't know what will happen as these many Chinese come back from holidays in Africa. Countries are on their highest alert. They are putting their surveillance and rapid response systems in place. If there are cases, I am sure that they will be catching and reporting.

Communication and trust are key to combating outbreaks. How can you do that in the face of social media spreading misinformation?

We have seen that clearly for this specific outbreak, the level of misinformation, the level of fear that it has generated. And some of that is fed by social media. We have to admit that we have a crisis on our hands -- a crisis of misinformation and fear.

We need to work with all forms of media to combat this. Without that it will become very difficult to win community trust, and we need the community to work very closely with public health experts to win this battle against the coronavirus -- both in preparedness and in the response phase.