* Ebola spread in Freetown alarms officials
* CDC seeks significant decrease in new cases in weeks
* Govt to restrict seasonal festivities (Adds comment from CDC)
By Emma Farge and Umaru Fofana
FREETOWN, Dec 17 (Reuters) - Sierra Leone said it would start house-to-house searches for Ebola patients on Wednesday and impose internal travel restrictions as part of a new push to combat the epidemic.
The measures are part of a month-long push in and around the capital Freetown by the government, a British taskforce and international groups that aims to make a breakthrough against the disease within four to six weeks.
Sierra Leone, Guinea and Liberia are at the heart of the world's worst recorded outbreak of Ebola. Rates of infection are rising fastest in Sierra Leone and the country has more than half of the 18,000 confirmed cases of the virus.
"Given the efforts we have undertaken we would expect to see a significant decrease in cases within several weeks," Tom Frieden, director of the U.S.-based Centers for Disease Control and Prevention, told Reuters during a visit to Freetown.
Health officials are alarmed by the widespread transmission in Freetown, which is similar to an earlier spread in Monrovia now slowly being brought under control. There is less experience fighting Ebola in urban areas than in rural ones, Frieden said.
Health workers will seek Ebola victims and anyone with whom they have had contact, transporting those infected to new British-built treatment centres, according to a government plan announced this week.
President Ernest Bai Koroma said that, under the new measures, worshippers on Christmas Day must return home after services and other festivities are banned. New Year's Eve services must stop by 5 p.m. local time (1700 GMT), while New Year's Day festivities are prohibited.
"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 in a nationwide address.
The government was also imposing restrictions on travel between districts, a ban on Sunday trading and the end of Saturday shopping at noon, Koroma said. He spoke one day after opening an Ebola Community Care Centre outside the capital. (Writing by Matthew Mpoke Bigg; Editing by Giles Elgood)