U.S. and Canadian researchers might have finally discovered a vaccine against one of the world’s deadliest disease caused by the Ebola virus.

Ebola usually begins suddenly with symptoms such as fever, headache, sore throat, weakness, joint muscle aches, diarrhea, vomiting and stomach pain. Symptoms may also include a rash, red eyes and bleeding. Ebola hemorrhagic fever has 90 percent mortality and, so far, there have been more than 1,500 cases in humans.

Dr. Anthony Sanchez of the Centers for Disease Control and Prevention in Atlanta said one of the candidate vaccines is about to be tested on people for the first time.

"The biothreat posed by Ebola virus cannot be overlooked. We are seeing more and more naturally occurring human outbreaks of this deadly disease. With worldwide air travel and tourism, the virus can now be transported to and from remote regions of the world. And it has huge potential as a possible weapon of bioterrorism. We desperately need a protective vaccine," Dr. Anthony Sanchez, of the U.S. Centers for Disease Control and Prevention, said in a prepared statement, the Washington Post reports.

The vaccine, developed by Canadian scientists last year, has been tested in three types of animals. The trial showed the vaccine kept at least half from dying when it was administered after infection. Four of eight primates injected with a lethal dose of Ebola virus survived when they were given the vaccine within 30 minutes of exposure.

“Ebola virus infection of humans can be highly lethal but monkeys rarely survive the infection and have been very useful as animal models. Ebola vaccine trials using nonhuman primates have provided unambiguous results and have allowed the development of protective vaccines to progress rapidly. Successful human trials will mean that we can vaccinate healthcare workers and other key personnel during outbreaks of Ebola hemorrhagic fever, helping us to protect their lives and control the spread of the disease,” said Dr. Sanchez.

Ebola virus is very dangerous and producing and testing a vaccine is extremely challenging for the scientists, as there are only a very limited number of high containment facilities with staff capable and authorized to conduct the research.

“Ebola virus is a Biosafety Level 4 threat, along with many other hemorrhagic fever viruses. As well as the difficulty in getting the right staff and facilities, vaccines for viruses like Ebola, Marburg and Lassa fever have been difficult to produce because simple 'killed' viruses that just trigger an antibody response from the blood are not effective. For these viruses we need to get a cell-mediated response, which involves our bodies producing killer T-cells before immunity is strong enough to prevent or clear an infection,” Dr. Sanchez said.

Dr. Sanchez presented an overview of the Ebola vaccine’s development on Monday at the Society for General Microbiology’s meeting in Edinburgh, Scotland.