By Roberta Rampton WINNIPEG, Manitoba, Oct 22 (Reuters) - Initial estimates of the number of infections and deaths linked to the recent outbreak of the deadly Ebola virus in the Democratic Republic of Congo probably were too high, a Canadian scientist said on Monday. But without extensive field studies in the remote region where the outbreak occurred, it will be difficult to more accurately estimate the number of infections and mortality rate, said Heinz Feldmann, who studies viral hemorrhagic fevers with the Public Health Agency of Canada. "It will be very difficult to say at the end which was an Ebola case and which were not," Feldmann said in an interview. Feldmann and a team of Canadians took a mobile laboratory to Congo last month at the request of the World Health Organization to help conduct rapid tests to determine whether residents were ill with Ebola or other illnesses with similar early symptoms, like Shigella dysentery and typhoid. Reports of more than 400 suspected cases and at least 174 deaths in the region of the outbreak were probably incorrect, Feldmann said. "They obviously had these kind of cases that looked like Ebola, but they are not confirmed," he said. "I personally think the numbers are lower than that, but I can't give you any estimates," he said. The World Health Organization said on Oct. 3 that 25 people had tested positive for Ebola out of 75 suspected cases, and another 187 people remained under observation for symptoms. It has been about 21 days -- the time the Ebola virus takes to incubate -- since the last confirmed infection, so international teams like the Canadian unit are leaving the area, Feldmann said. The WHO typically waits twice the length of the incubation period after the last infection to declare that an outbreak has ended, he said. The outbreak so far appears to be similar to other outbreaks of the severe disease, he said. "What is clearly evident at the moment is that the case fatality rate is fairly low, but that of course depends on the numbers," he said. Ebola is normally fatal in 50 to 90 percent of cases, and is spread by contact with blood and bodily fluids of infected people. About 1,850 cases with more than 1,200 deaths have been documented since the virus was discovered in 1976. Feldmann heads a Canadian team that is developing a vaccine for Ebola and Marburg viruses. LINKS: * World Health Organization photo story of Ebola response http://www.who.int/features/2007/ebola_cod/en/index.html
