The Ebola outbreak could have a catastrophic impact on the economies of Guinea, Liberia and Sierra Leone, the World Bank says.
The organisation says the economic impact of the virus could “grow eight-fold” in the “already fragile states”.
However, it says the cost can be limited if the epidemic – and the accompanying fear – is contained by a fast global response.
Ebola has killed 2,461 people in West Africa – the largest ever outbreak.
Earlier on Wednesday, US President Barack Obama called the latest outbreak “a threat to global security”, as he announced a larger US role in fighting the virus.
The measures announced included ordering 3,000 US troops to the region and building new healthcare facilities.
The announcement came as UN officials described the outbreak as a health crisis “unparalleled in modern times”.
The World Bank’s analysis said billions of dollars could be drained from West African countries by the end of next year if the virus continued to spread.
Under the worst-case scenario, the global development lender predicted that economic growth next year could be reduced by 2.3 percentage points in Guinea and 8.9 percentage points in Sierra Leone.
It predicted Liberia’s economy would be hardest-hit, losing 11.7 percentage points off its growth next year.
In a statement released on Wednesday, Liberian President Ellen Sirleaf Johnson welcomed the US plan to combat Ebola, saying she hoped it would “spur the rest of the international community into action”.
“This disease is not simply a Liberian or West African problem. The entire community of nations has a stake in ending this crisis,” the statement said.