More than 1,500 people have died of the Ebola virus in four affected West African nations since the start of the year. And now a leading American health offcial warned that the Ebola outbreak will only get worse.

"There is need for urgent action. The world has never seen an outbreak of Ebola like this. I wish I didn't have to say this, but it is going to get worse, before it gets better," says Dr Tom Frieden, the director of the US Centers for Disease Control and Prevention.

The World Health Organisation (WHO) says it needs $490m to help combat the world's worst outbreak of the virus, and it will be some time before they will be able to fully control its spread. Although there are controversial treatments now being trialled, there are no known cures. 

Along with the medical emergency, the impact of the outbreak on business in the region is increasingly being felt. Most of the affected countries, and their neighbours have closed borders to stop the virus spreading. This has killed off what was vibrant trade in commodities - such as palm oil. 

In the last two days both Air France and British Airways have suspended flights to the region - a move the United Nations says makes it harder to tackle the virus, and hurts the economies.

Sierra Leone had hoped to export $200m worth of diamonds this year, but the government says the outbreak will prevent it from meeting this target with miners too afraid to go to diamond pits in the country's east - where there have been cases of Ebola. 
  
This week, the African Development Bank donated $60m towards essential supplies to help train medical workers, but says the outbreak could cost the affected countries up to 4 percent of their GDP.

So how can this crisis be tackled? Why is there still no approved treatment for the Ebola virus? And why is the pharma industry not interested?

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