Doctors in Liberia were out on strike on Tuesday as they struggled to cope with the outbreak of the deadly Ebola virus, while the United Nations warned the spread of the disease in West Africa was causing food shortages in one of the world’s poorest regions.

Governments and aid organisations are scrambling to contain the disease, which has killed more than 1,500 since March. Medical charity Medecins Sans Frontieres (MSF) said 800 more beds for Ebola patients were urgently needed in the Liberian capital Monrovia alone, while in Sierra Leone highly infectious bodies were rotting in the streets.

MSF called for rich nations to send military medical teams to support buckling healthcare systems in West Africa.

U.S. missionary organisation SIM USA said on Tuesday that an American doctor treating obstetrics patients at the ELWA hospital in Monrovia had tested positive for Ebola. The doctor, who was not working in the hospital’s Ebolatreatment centre, was in an isolation ward at the hospital and was responding well so far, SIM said on its Web site.

Scores of staff went on strike at the John F. Kennedy Medical Center (JFK) in Monrovia in a protest over unpaid bonuses and working conditions. More than 120 healthworkers have died in West Africa during the Ebola outbreak amid shortages of equipment and trained staff.

“Health workers have died (fighting Ebola), including medical doctors at … JFK and to have them come to work without food on their table, we think that is pathetic,” George Williams, secretary general of the Health Workers Association of Liberia, told Reuters.

Williams said healthcare workers at JFK, the country’s largest referral hospital, had gone unpaid for two months.

The strike followed a one-day protest over pay and conditions at the Connaught hospital in Sierra Leone’s capitalFreetown on Monday. Staff at the main Ebola clinic at Kenema in eastern Sierra Leone also walked off the job last week, in protest at conditions.

The World Health Organisation and other international bodies are rushing to support fragile healthcare systems in affected countries, but additional staff and resources have been slow to arrive.

The president of MSF, Joanne Liu, said in a speech to U.N. members in New York that the outbreak was now an issue of international security and needed specialised biological disaster response teams to contain it, both civilian and military.

“Six months into the worst Ebola epidemic in history, the world is losing the battle to contain it,” Liu said, slamming what she called “a global coalition of inaction.”

Liu called for the urgent dispatch of field hospitals with isolation wards and mobile medical laboratories to West Africa.

FOOD PRICES SURGE

In Monrovia, MSF said its new ELWA 3 centre, which has 160 beds, was already overflowing with patients. “Every day we have to turn sick people away because we are too full,” said Stefan Liljegren, MSF coordinator at the site.

Putting further pressure on the ability of the region’s governments to spend money on healthcare, the epidemic has also put harvests at risk and sent food prices soaring in West Africa, the U.N. Food and Agriculture Organisation (FAO) said.

The FAO issued a special alert over food security for Liberia, Sierra Leone and Guinea, the three countries most affected by the outbreak, which was detected in the forests of southeastern Guinea in March.

Restrictions on people’s movements and the establishment of quarantine zones to contain the spread of the haemorrhagic fever has led to panic buying, food shortages and price hikes in countries ill-prepared to absorb the shock.

“Even prior to the Ebola outbreak, households in some of the most affected areas were spending up to 80 percent of their incomes on food,” said Vincent Martin, head of an FAO unit in Dakar coordinating the agency’s response. “Now these latest price spikes are effectively putting food completely out of their reach.”

The director of the U.S. Centers for Disease Control and Prevention, Tom Frieden, said the outbreak was accelerating very fast and urged more global support to combat it.

“It’s spiralling out of control. The situation is bad and it looks like it’s going to get worse quickly. There is still a window of opportunity to tamp it down but that window is closing,” he told NBC News following a visit to the region.

“This is different than every other Ebola situation we’ve ever had. It’s spreading widely, throughout entire countries, through multiple countries, in cities and very fast,” he said.

Frieden called on health officials to reverse the outbreak by sending in more resources and specialised workers, adding that the U.S. government now had 70 people in the region.

The death toll from an Ebola outbreak in the Djera region of northern Democratic Republic of Congo has risen to 31, Minister of Health Felix Kabange Numbi told Reuters on Tuesday.

The outbreak in Congo’s Equateur province is thought to be separate from the West African epidemic.