The true number of Ebola virus cases in West Africa has been underestimated partly because of the existence of "shadow zones" and the hiding of sick individuals by family members, according to the World Health Organization.
In a statement issued by the United Nations health agency on Friday, officials listed several reasons why authorities have been unable to accurately calculate the magnitude of the outbreak.
The list included the existence of shadow zones, or small villages where rumors of an outbreak could not be investigated because of "community resistance" or lack of staff or vehicles.
"Many families hide infected loved ones in their homes," the statement read. "As Ebola has no cure, some believe infected loved ones will be more comfortable dying at home. ... In rural villages, corpses are buried without notifying health officials and with no investigation of the cause of death. In some instances, epidemiologists have traveled to villages and counted the number of fresh graves as a crude indicator of suspected cases."
As of Friday, the WHO had estimated a total of 2,615 cases of Ebola with 1,427 deaths in Guinea, Liberia, Sierra Leone and Nigeria. The outbreak was first detected in March.
In a telephone news conference from the Liberian capital of Monrovia on Friday, WHO Assistant Director-General for Health and Security Keiji Fukuda estimated that the epidemic would last another six to nine months.
"We hope to see a decrease in cases before that," Fukuda said. "But we know that Ebola is an infection that will take a while to get rid of, and so this is simply an estimate."
Fukuda and other WHO officials had spent two days talking with Liberian government officials and aid agencies about responding to the Ebola crisis and expanding medical capacity.
As resources had been shifted to deal with the outbreak, people were not getting care for non-Ebola-related health problems, a secondary effect of the crisis that will grow more serious as time goes on.
Fukuda said that plans were in the works to provide up to 500 more Ebola care beds in Monrovia in the next six weeks.
At the same time, WHO officials said that the government and aid organizations had to ensure that quarantined areas received food and other aid.
"The situation is not a hopeless situation," Fukuda said. "Ebola is not a new disease. ... It is clear when patients are given the right treatment early enough it makes a difference. People survive this disease."