More than 4,000 people have died from Ebola so far, according to the World Health Organization.

A WHO official said at a press conference on Tuesday there could be up to 10,000 new cases of Ebola per week within two months. Dr. Bruce Aylward said for the last four weeks there have been 1,000 new cases per week -- a figure that includes suspected, confirmed and probable cases -- and if response isn't stepped up within 60 days, "a lot more people will die."

Aylward also said the death rate has increased to 70 percent for the high mortality disease. Previous estimates on the death rate were 50 percent.

The international aid organization, Doctors Without Borders also said Tuesday that 16 of its staff have been infected with Ebola and nine of them have died. The aid organization said there has been inadequate assistance from the international community, and while people have publicly pledged support, the situation has not improved in the affected countries.

Ebola screening by customs and health officials at airports in Washington's Dulles, Chicago's O'Hare, Atlanta's Hatsfield-Jackson and Newark's Liberty will start on Thursday with officials taking the temperatures of passengers from Guinea, Liberia and Sierra Leone. Federal health officials said screeners will use no-touch thermometers to try to find passengers with fevers, and that screenings add another layer of protection to halt the spread of the Ebola virus. Screenings started at New York's Kennedy International Airport on Saturday. One hundred and fifty people come to the US daily through or from the three African countries with the Ebola virus, and 95 percent travel to the five major airports.

In New Jersey hospitals, the Health Department is staging drills to test their emergency departments' readiness to handle Ebola cases this week. They will be sending fake patients to the hospital to see if staff identifies "patients" as potential Ebola patients and handles the case appropriately.

The precautionary measure comes after Thomas Eric Duncan -- the first confirmed case of Ebola in the U.S. died despite his checking into a Dallas hospital with Ebola-like symptoms and being sent home. Between 50-70 people are being screened for symptoms following their contact with Duncan. One Texas nurse has contracted the virus. The nurse helped care for Duncan but protocols were breached according to officials. For moment, the nurse, Nina Pham who's 26 is stable.

CDC Director Dr. Tom Frieden on Monday, according to NBC News said, "We have to rethink the way we address Ebola infection control, because even a single infection is unacceptable."

The National Nurses United said however in a survey they don't think hospitals are adequately equipped to deal with a possible domestic outbreak of Ebola. In the poll 76 percent of the 1,900 nurses sampled said that no policy regarding suspected Ebola patients had been shared with staff and that more hands on training is required as well as ample protective equipment in the event a patient is admitted.

The CDC issued Ebola symptoms to watch and monitor. It is passed by human to human bodily fluids -- blood, feces and vomit. Possibly saliva and tears, but it is not airborne. Symptoms include fever greater than 101.5 Fahrenheit, severe headache, muscle pain, weakness, diarrhea, vomiting, abdominal pain, unexplained hemorrhage (bleeding or bruising). Symptoms may appear anywhere from two to 21 days after exposure -- the average is eight to 10 days. Recovery depends on a patient's immune response and people who recover from Ebola infection develop antibodies that last for at least 10 years. Ebola when full blown is often fatal in humans with a fatality rate of 70 percent. There is no license vaccine, but two potential ones are being evaluated.