an illness or disease that affects the population of a very large area
全国的(世界的)に流行の病気
endemic
an endemic disease or problem is always present in a particular place
, or among a particular group of people
地方病、風土病
epidemic
a large number of cases of a particular infectious disease happening at the same time
流行病
(ロングマン現代アメリカ英語辞典、ジーニアス第3版、リーダーズ第2版)
A UN official recently estimated that if the bird flu virus combined with the human influenza virus, it could lead to a devastating global pandemic
that could kill between five million and 150 million people.