The World Health Organization has for the first time expressed "cautious optimism" that the growth in new Ebola cases in West Africa may be slowing down. Bruce Aylward, who is in charge of the WHO response to Ebola, said in Geneva that he was particularly encouraged by evidence of a downward trend in Liberia, one of the three worst-affected countries. The WHO's official total number of Ebola cases has reached 13,703 - a big jump from the10,141 cases it reported four days ago. But Dr Aylward said that was mainly the result of the data being updated with old cases, rather than new cases arising. "Do we feel confident that the response is now getting an upper hand on the virus? Yes, we are seeing a slowing rate of new cases, very definitely," Dr Aylward said. However, Dr Aylward also urged people not to celebrate pre-maturely over any apparent downturn in the epidemic  . "I'm terrified that the information will be misunderstood and people will think Ebola is under control," he said. Any reduction in the battle against the virus might lead to "an oscillating  pattern where the disease moves up and down". The improvement in Liberia seems to be due to a combination of more treatment facilities, better contact tracing and safer burial practices, together leading to fewer new infections from Ebola patients. In Sierra Leone the number of cases continues to increase in some areas. "We're still seeing this thing _ in parts of Sierra Leone," Dr Aylward said Tracing the progress of individual patients, the WHO estimates an overall death rate of 70 percent, though people who receive treatment in a well-equipped clinic are slightly less likely to die. The WHO plans to set up 56 Ebola clinics with 4,700 beds in West Africa. Of these 15 clinics with 1,050 beds are already operational and another 22 clinics are expected to open during November. Meanwhile, two former NATO  secretaries-general and dozens of leading European politicians have urged the alliance  to send troops, aircraft and ships to west Africa to help contain the Ebola crisis. Which of the following didn't contribute to the improvement in Liberia?
better contact tracing more treatment facilities safer burial practices data updated with old cases