In Liberia, a missionary organization announced that another American doctor has become infected.
Doctors Without Borders President Joanne Liu said her organization is completely overwhelmed by Ebola outbreak in four West African countries. She said treatment centers can offer little more than palliative care and called on other countries to contribute civilian and military medical personnel familiar with biological disasters.
World Health Organization Director Margaret Chan warned that the outbreak would "get worse before it will get better" and would require a larger global response. She thanked countries that have helped but said: "We need more from you. And we also need those countries that have not come on board."
The latest missionary to come down with the disease, a male obstetrician, was not immediately identified by the group Serving In Mission. He did not work in an Ebola ward. The group did not specify how he contracted Ebola, but it can be spread through vaginal fluids.
Bruce Johnson, the group's president, said the organization was "surrounding our missionary with prayer" and Liberian colleagues who continue fighting the epidemic.
Last month, two Americans, including one from SIM, were evacuated to the United States for treatment after contracting Ebola in Liberia. The two received an experimental drug known as ZMapp and recovered. The manufacturer says it has run out of supplies of the drug and it will take months to produce more.
David Nabarro, who is coordinating the U.N. response, said the world body is "bringing in outside health workers as much as we can."
But Ameerah Haq, head of U.N. peacekeeping's Department of Field Support, warned that before bringing in external expertise, guarantees are needed for medical evacuations and treatment for any workers who become infected. Haq said "without one, the other will not happen."
The Ebola outbreak in West Africa has killed more than 1,500 people in Guinea, Liberia, Sierra Leone and Nigeria.
Earlier Tuesday, the U.N. Food and Agriculture Organization warned that food in countries hit by Ebola is becoming more expensive and will become scarcer as farmers can't reach their fields.
Authorities have cordoned off entire towns in an effort to halt the virus' spread. Surrounding countries have closed land borders, airlines have suspended flights to and from the affected countries and seaports are losing traffic, restricting food imports to the hardest-hit countries. Those countries — Guinea, Liberia and Sierra Leone — all rely on grain from abroad to feed their people, according to the U.N. FAO.
For instance, the price of cassava root, a staple in many West African diets, has gone up 150 percent in one market in Liberia's capital, Monrovia.
"Even prior to the Ebola outbreak, households in some of the affected areas were spending up to 80 percent of their incomes on food," said Vincent Martin, who is coordinating the food agency's response to the crisis. "Now these latest price spikes are effectively putting food completely out of their reach."
An estimated 1.3 million people in Guinea, Liberia and Sierra Leone will soon need help feeding themselves, said the U.N.
Chan and other officials at the U.N. forum criticized the border closures because they are preventing supplies from reaching people in desperate need.
"The three worst-hit countries are isolated," Chan said. "We cannot fly in our experts for help."
The situation will likely worsen because restrictions on movement are preventing laborers from getting to farms and the harvest of rice and corn is set to begin in just a few weeks, the FAO said.
Ivory Coast decided Monday night to keep its borders with Guinea and Liberia closed but said it would open a humanitarian corridor to allow supplies in.
A separate Ebola outbreak has hit a remote part of Congo, in Central Africa, the traditional home of the disease. So far, 53 cases consistent with Ebola have been identified there, of whom 31 have died, WHO said Tuesday.
Associated Press Writer Marc-Andre Boisvert in Abidjan, Ivory Coast, contributed to this report.
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