The death toll from the world's worst-ever Ebola outbreak in West Africa has risen to 603 since February, with at least 68 deaths reported from three countries in the region in the past week alone, the World Health Organization said on Tuesday.

The WHO said there were 85 new cases between July 8 and 12, highlighting continued high levels of transmission. International and local medics were struggling to get access to communities, as many residents feared outsiders were spreading rather than fighting Ebola.

"It's very difficult for us to get into communities where there is hostility to outsiders," WHO spokesman Dan Epstein said at a media briefing in Geneva. "We still face rumors, and suspicion and hostility … People are isolated, they're afraid, they're scared."

Sierra Leone recorded the highest number of the latest deaths, which include confirmed, probable and suspected cases of Ebola, with 52. Liberia reported 13 and Guinea three, according to the WHO figures.

Ebola, one of the world’s deadliest diseases, is marked by vomiting, diarrhea and hemorrhagic fever that can cause its victims to bleed from the ears and nose. It was first detected in what was then Zaire, now the Democratic Republic of the Congo, in the mid-1970s. Spread through contact with blood and body fluids of infected people or animals, the virus kills up to 90 percent of those infected.

It has reached the capitals of all three countries in this outbreak, which is now the largest on record.

The key to halting Ebola is isolating the sick, but fear and panic have sent some patients into hiding, complicating efforts to stop its spread. Epstein said the main focus in the three countries is tracing people who have been exposed to others with Ebola and monitoring them for the 21-day incubation period to see if they are infected, but he added it would probably be “several months before we are able to get a grip on this epidemic.”

This Ebola virus is a new strain and did not spread to West Africa from previous outbreaks in Uganda and Congo, researchers say. Many believe it is linked to the human consumption of bats carrying the virus. Many of those who have fallen ill in the current outbreak are family members of victims and the health workers who treated them.

Guinea first notified the WHO about the emergence of Ebola in March and, soon after, cases were reported in neighboring Liberia. Two months later, there were hopes that the outbreak was waning, but then people began falling ill in Sierra Leone.

Some desperate relatives have brought their loved ones to capital cities in search of better medical care, unknowingly spreading the deadly disease. Preachers are calling for divine intervention, and panicked residents in remote areas have on multiple occasions attacked the very health workers sent to help them.

In one town in Sierra Leone, residents partially burned down a treatment center over fears that the drugs given to victims were actually causing the disease. In Liberia, health workers have been chased away by armed gangs.

Doctors Without Borders says it fears the number of patients now being treated in Sierra Leone could be "just the tip of the iceberg." Nearly 40 cases were reported in a single village in the country's east.

There is no cure and no vaccine for Ebola, and those who have survived managed to do so only by receiving rehydration and other supportive treatment. Ebola's high fatality rate means many of those brought to health clinics have been merely kept as comfortable as possible in quarantine as they await death. As a result, some families have been afraid to take sick loved ones to the clinics.

"Let this warning go out: Anyone found or reported to be holding suspected Ebola cases in homes or prayer houses can be prosecuted under the law of Liberia," President Ellen Johnson Sirleaf stated recently.

Her comments came just days after Sierra Leone issued a similar warning, saying some patients had discharged themselves from the hospital and had gone into hiding.

At the airport in Guinea's capital, Conakry, departing passengers must undergo temperature screening, and those with a fever are pulled aside for further evaluation. Still, the stigma of Ebola follows Guineans well outside the region.

"The police treated us like we were aliens. They said they didn't want us in their country because of the disease affecting Guinea," says Tafsir Sow, a businessman who was briefly detained at the airport in Casablanca, Morocco, before continuing on to Paris. "I had tears in my eyes."

Still, WHO health officials are hopeful they will be able to get the situation under control in the next several weeks. A recent conference in the Ghanaian capital, Accra, brought together health authorities from across the affected areas, and the countries agreed on a common approach to fight Ebola.

"When you have it spread, of course it's moving in the wrong direction," said Dr. Keiji Fukuda, WHO's assistant director-general for health security and environment. "You want to see the number of infections going down. So we really have to redouble our efforts. But saying that it's out of control makes it sound like there are no solutions. This is a virus for which there are very clear solutions."

Wire services