FREETOWN, Sierra Leone -- Ebola surveillance teams fanned out Wednesday in Sierra Leone's capital to search every house for sick people, as the president imposed new restrictions on movement and gatherings in a bid to stop the disease's spread.

President Ernest Bai Koroma launched the 14-day "Operation Western Area Surge" in a national broadcast, promising that treatment beds, labs and ambulances are ready to handle any new cases. He reiterated that Christmas and New Year's celebrations are cancelled and also banned all public gatherings during the holidays and movement between districts.

"I know that this is the festive season where Sierra Leoneans often celebrate with families in a flamboyant and joyous manner, but all must be reminded that our country is at war with a vicious enemy," he said.

Sierra Leone has repeatedly quarantined hot spots and once locked down the entire country to ferret out the sick, but infections continue to rise and the disease is now whipping around Freetown and its surroundings. There was no order Wednesday for people to stay in their homes.

By contrast, infection rates have begun to stabilize or decline in neighbouring Guinea and Liberia, the other two countries hit hard by Ebola. In all, the disease has sickened around 18,500 people.

But Tom Frieden, head of the U.S. Centers for Disease Control and Prevention, warned against comparing Sierra Leone to Liberia. Ebola hit the Liberian capital fairly early in the outbreak and cases surged there this summer, while the disease first struck rural Sierra Leone and only recently began hitting urban areas hard.

The international response in Sierra Leone is robust and there is no need to send in U.S. troops, said Frieden, who was in Sierra Leone on Wednesday. U.S. troops have been building treatment centres in Liberia, while British troops have been part of the response in Sierra Leone.

"The fight is going to be long and hard to get to zero cases, which requires individuals to come forward and be identified, isolated and cared for," said Frieden, who praised the operation launched Wednesday to find new cases.