北师大版高中英语模块7--Unit 21 Lesson3-1

（单词翻译）

[00:02.37]Unit21 Human BiologyLesson3 Epidemics² Explained
[00:09.57]Epidemics throughout history
[00:12.34]With new health threat on the rise,
[00:14.33]James Madison looks at epidemics
[00:16.13]throughout history.
[00:18.09]Bacteria and viruses have been around
[00:20.34]since the beginning of life
[00:21.78]on Earth and many of today's diseases
[00:24.10]have existed as long as humans have.
[00:27.33]It's important to look at the spread
[00:28.88]of diseases throughout history to discover
[00:31.24]the causes and effects of epidemics.
[00:34.41]Epidemics are described in historical accounts
[00:37.13]as early as 430 BC
[00:39.87]and one of the earliest on record
[00:41.68]is Justinian's Plague.
[00:43.62]It happened about 500-550
[00:47.64]as Roman Emperor Justinian
[00:49.87]was attempting to rebuild and acquire more land
[00:52.47]for the Roman Empire.
[00:54.03]It swept through North Africa,
[00:55.71]the Middle East and Europe.
[00:58.15]Scientists now think taht Justinian's Plague
[01:00.83]was actually a disease called bubonic plague.
[01:04.34]They estimate that between 25% and 50%
[01:07.95]of the area's population died
[01:10.08]from the disease and think that the epidemic¹
[01:12.34]was one of the key causes
[01:13.70]of the fall of the Roman Empire.
[01:14.91]