The number of Ebola infections in Liberia and Sierra Leone could skyrocket to 1.4 million by January 2015, according to a worst-case scenario released by US health authorities.
The US Centers for Disease Control and Prevention estimated that Ebola cases in these two West African nations could range from between 550,000 and 1.4 million cases by January 20, 2015.
The estimate is based on the assumption that Ebola cases in the world's largest outbreak to date are being under reported by a factor of 2.5, the report from the CDC said.
However, experts warned the figures are based on data available in August, before the United States ramped up its response to the epidemic in West Africa, which has killed about half of the 6000 infected.
"The numbers do not reflect current conditions," said a CDC statement on the projection, published in the agency's Morbidity and Mortality Weekly Report.
"Modelling suggests that extensive, immediate actions - such as those already started - can bring the epidemic to a tipping point to start a rapid decline in cases."
The UN health agency earlier on Tuesday said that new cases would increase from hundreds each week to thousands without "drastic improvements in control measures", with infections increasing to 20,000 by November.
"If we move fast enough we can turn it around," CDC chief Tom Frieden said.
"I am confident that the most dire predictions are not going to come to pass."
