New potential vaccines have been developed that protect animals against the bacteria that causes the deadly plague. The plague of Black Death infamy has had the power to strike fear in people since the Middle Ages -- and for good reason. Once someone begins to show symptoms, the disease progresses very quickly and is almost 100 percent fatal without prompt treatment. The World Health Organization has categorized the bacteria responsible for plague, Yersinia pestis, as a re-emerging pathogen because of the rising number of human plague cases globally.

Source: New candidate vaccines against the plague