Reine
clinomania
A pestilence is a fatal disease. And in this case, it's mostly true. Those affected with it do indeed die. For a little while, anyway.
The population swooped down to one billion by the end of 2018. All those who died seemed to do so mysteriously, determined to be from a disease transmitted by liquids, such as kissing or contact with bodily fluids such as vomit or... other things.
In 2019 those who were dead were reanimated. It took about two months for them to become humanoids that preferred flesh over sandwiches. Then, the population dropped to 200,000 in the next year. The world is no longer ours. It belongs to the pestilence.