Ebola is spreading so fast it is on its way to becoming a global pandemic that could rival AIDS, according to the head of the CDC. The Ebola outbreak has killed more than 3,860 people, including 200 health workers

Dr. Tom Frieden, the director of the Centers for Disease Control and Prevention, called for immediate action to curb the spread. The U.S. military announced it will be sending up to 4,000 Marines to help build medical centers in Liberia. The Ebola crisis overtaken medical staffing and beds in Sierra Leone and Liberia.

In an email to the AP, U.S. Army Capt. R. Carter Langston said "Two different flights of MV-22 Osprey and KC-130 aircraft, along with U.S. Marines, will arrive to support the whole-of-government effort to contain Ebola."

British airports are now questioning passengers who arrive from West Africa to stop Ebola from entering the U.K. Downing Street says the screening process will begin within days. Defense Secretary Michael Fallon originally ruled screening out as an option because he believed it could create "hysteria."

According to the World health Orgnization (WHO) the three countries with the worst situation are Guinea, Liberia and Sierra Leone, The countries are all experiencing widespread and intense transmission. There is a 48 percent fatality rate. According to the WHO report, there had been 3,865 deaths as of Oct. 5 out of 8,033 confirmed cases.

CDC Director Frieden told a World Bank Conference in Washington D.C., "In the 30 years I've been working public health, the only thing like this has been AIDS, and we have to work now so that this is not the world's next AIDS.  Speed is the most important variable here. This is controllable and this was preventable. It's preventable by investing in core public health services, both in the epicenter of the most affected countries, in the surrounding countries, and in other countries that might be affected."

The WHO released a report on Wednesday saying seven countries are affected. Five countries in West Africa and the United States were confirmed to be affected as of Oct. 5. There was a confirmed case of Ebola in Spain this week. A nurse tested positive for the disease.