“I’m working with the burial team, and the first question I ask them is, ‘Are they Ebola-positive?’ ” said Mr. Parker, adding that the figures were based on medical certificates that he had seen himself. The deaths are carefully recorded by name and date in a notebook headed “Ebola Burials.”

A burial team supervisor who drove up with fresh bodies echoed Mr. Parker’s assertion. “Any body we collect is a positive case,” said Sorie Kessebeh. “All the bodies that we are bringing in are positive.”

Beyond the many worrisome trends in the Ebola epidemic seizing parts of West Africa — the overflowing hospitals, the presence of the disease in crowded cities, the deaths of scores of health workers trying to help — another basic problem has stymied attempts to contain the disease: No one seems to know how bad the outbreak really is.