Epidemic. Plague, which has been pandemic, is in many ways different from Ebola, which is currently epidemic in West Africa. Yersinia pestis is part of a cycle involving bacteria infected rodents who infect fleas, who infect people. Ebola is theorized to be spread by fruit bats that drop contaminated fruit, which is then eaten by Diuker antelopes, monkeys, apes or other mammals.
Dangerous viruses. Good hygiene and medications will treat the bubonic plague. Unfortunately there are some very dangerous viruses out there that may spread to humans from both birds and a study done today found a new virus in seals that may have potential to jump to humans. These viruses mutate very fast and frankly there probably isn't anything that we could do other than isolation to prevent spread.