Liberian officials fear Ebola could soon spread through the capital’s largest slum after residents raided a quarantine center for suspected patients and took items including bloody sheets and mattresses. Photo: Getty Images

DAKAR, Senegal—The Ebola outbreak that has killed more than 1,000 people has turned parts of West Africa into a medical battle zone and could last up to six more months, Doctors Without Borders warned Friday as a worker on the front lines in Liberia acknowledged that the true death toll is unknown.

Tarnue Karbbar, who works for the aid group Plan International in northern Liberia, said response teams simply aren’t able to document all the cases erupting. Many of the sick are still being hidden at home by their relatives, too fearful of going to an Ebola treatment center.

Others are buried before the teams can get to the area, he said. In the last several days, some 75 cases have emerged in a single district.

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“Our challenge now is to quarantine the area to successfully break the transmission,” he said, referring to the Voinjama area.

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Beds in Ebola treatment centers are filling up faster than they can be provided, evidence that the outbreak in West Africa is far more severe than the numbers show, an official with the World Health Organization said Friday.

Photos: A Grim Picture of Liberia’s Ebola Crisis

See a photographer’s chronicles of the country’s bid to contain the outbreak. Above, the leader of a burial team from the Liberian health department on Thursday asks local residents for the location of the body of a woman suspected of dying of the Ebola virus in Monrovia. John Moore/Getty Images

On Friday, Doctors Without Borders likened the situation to a state of war and said the outbreak could last six more months.

“We’re running behind a train that is going forward,” Joanne Liu, the medical charity’s international president, told reporters in Geneva on Friday. “And it literally is faster than what we’re bringing in terms of a response.”

The U.N. health agency warned Thursday that the official counts of 1,069 dead and 1,975 infected may still “vastly underestimate the magnitude of the outbreak.”

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It said extraordinary measures are needed “on a massive scale to contain the outbreak in settings characterized by extreme poverty, dysfunctional health systems, a severe shortage of doctors, and rampant fear.”

The flood of patients into every newly opened treatment center is evidence that the official tolls aren’t keeping up, Gregory Hartl, a spokesman for WHO, said from Geneva.

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A Liberian health worker disinfects a corpse Friday after the man died in a classroom now used as Ebola isolation ward in Monrovia. John Moore/Getty Images

Hartl said that an 80-bed treatment center opened in Liberia’s capital in recent days filled up immediately. The next day, dozens more people showed up to be treated.

Ebola causes a high fever, bleeding and vomiting. It has no cure and no licensed treatment and has been fatal in at least 50% of the cases, health experts say. The disease is usually found in eastern or central Africa, typically in rural, isolated communities, where outbreaks tend to be “self-limiting,” Hartl said.

By contrast, the current outbreak spread quickly to cities and the capitals of Guinea, Liberia and Sierra Leone, making it difficult to stop.

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