An unknown scientists showed out and presented a potion for this situation. He said, "This is the antidote for Ebola virus."
But it was just a hoax, the scientist works for Umbrella Corp, they want to have zombie apocalypse through spreading out the virus
Ohhhh, , , (Blackbeard will going to be envy for this one.) maybe this is why Jack Sparrow died in the part 2. Alien made him more powerful.
black beard died due to heart attack, thinking so much about sparrow. but umbrella corp revived him and turned him into a killing machine . well, this make thing fair enough