DAKAR, Senegal (AP) -- An Ebola outbreak continues to spread in three West African countries, with more than 330 deaths reported, the World Health Organization said Wednesday.
Health officials have struggled to contain what is one of the deadliest recorded outbreaks of Ebola. Most of the cases and deaths have been in Guinea, where the outbreak is believed to have begun.
In an update published on its website Wednesday, the U.N. health agency said that more than 500 suspected or confirmed cases of the virus have been recorded. It said 337 reported deaths have been linked to the virus.
Daniel Bausch, director of the Emerging Infections Department at the U.S. Naval Medical Research unit in Peru, said this appeared to be the largest number of cases ever recorded, but cautioned that not every Ebola case is captured, either in previous outbreaks or the current one.
"I don't think there's any denying that this is a very large outbreak, and it's unfortunately going to get larger for a while," said Bausch, who is a doctor and professor at Tulane University and has traveled to West Africa to help with the response.
The figures released Wednesday appear to show a large uptick since the last update, published about a week earlier, when the agency reported about 240 deaths have been linked to the disease. But there is sometimes a significant lag in tallying cases, and the organization said the numbers are constantly in flux as tests come in.
"The jump in cases is due to reclassification, retrospective investigation, and consolidation of cases,"Fadela Chaib, a spokeswoman for the U.N. health agency, wrote in an email.
This is the first time Ebola has struck three countries at once and the first major outbreak in West Africa. Fear of the disease, which causes horrible bleeding and for which there is no cure, has hampered efforts to isolate the sick.
Chaib said more work needs to be down to get sick people into treatment facilities and to track down people that the sick have come into contact with, so they can be monitored for symptoms.
"This is a complex outbreak involving multiple locations in three countries with a lot of cross-border movement among the communities," Chaib wrote. "This makes this one of the most challenging Ebola outbreaks ever."
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.