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国際バカロレア · IB Diploma · Biology · HL トピック 5 3:46 英語ナレーション・英語＋中文字幕 burning-in
章
Transcript
An antibiotic may help against a bacterial infection but fail against a viral illness.
抗生素可能对细菌感染有效，但对病毒感染无效。
Treatment depends on the causal organism and the evidence supporting diagnosis.
治疗方案取决于致病菌以及支持诊断的证据。
Pathogens cause infectious disease.
病原体引起传染病。
Physical barriers, phagocytosis and specific immune responses reduce infection.
物理屏障、吞噬作用和特异性免疫反应可降低感染风险。
Antibodies bind particular antigens.
抗体与特定抗原结合。
Vaccination exposes the immune system to antigen safely enough to develop memory.
疫苗接种使免疫系统在安全条件下接触抗原，从而产生记忆。
A pathogen is an agent that causes disease.
病原体是致病的因子。
An antigen is a structure recognized by a specific immune response.
抗原是被特异性免疫反应识别的结构。
After vaccination, memory cells can support a faster secondary response.
接种疫苗后，记忆细胞可支持更快的二次免疫应答。
Antibiotic resistance arises through heritable variation and selection.
抗生素耐药性通过可遗传变异和自然选择产生。
An individual bacterium does not choose to become resistant because it needs to survive.
单个细菌不会为了生存而主动选择变得耐药。
In the lab: Use published infection data to compare rates per equal population size.
在实验室中，使用已发表的感染数据来比较同等人口规模下的感染率。
Distinguish prevalence at a time from new cases over a period.
区分某一时刻的患病率与一段时间内的新发病例数。
In school, use safe simulations or approved cultures rather than collecting unknown pathogens.
在学校里，应使用安全模拟或经批准的培养物，而不是采集未知的病原体。
Known: 18 cases occur in 900 people.
已知：900人中有18例。
Rate per 1,000 equals cases divided by population, times 1,000.
每千人率等于病例数除以人口数，再乘以1,000。
Rate equals 18 divided by 900, times 1,000, which is 20 cases per 1,000.
即18除以900，乘以1,000，结果为每千人20例。
A second group with 10 cases in 250 people has 40 per 1,000, even though it has fewer cases.
第二组在250人中有10例，其每千人率为40，尽管该组病例总数较少。
Your turn: 12 cases occur among 600 people.
轮到你了：600人中有12例病例。
Find cases per 1,000 people.
求每1,000人中的病例数。
Pause the video and work it out.
请暂停视频，自己算一算。
Check: 12 divided by 600, times 1,000, gives 20 cases per 1,000 people.
核对：12 ÷ 600 × 1000，得每千人 20 例。
Antibiotics do not act on viruses in the same way they act on bacteria.
抗生素对病毒的作用方式与对细菌不同。
A vaccine is not an immediate cure for an established infection.
疫苗并非针对已建立感染的即时疗法。
Not true: Every antibiotic is effective against every viral infection.
不正确。 并非每种抗生素都对所有病毒感染有效。
Antibiotics act on bacterial structures and processes that viruses do not have, so they cannot cure a viral infection.
抗生素作用于细菌具有而病毒不具备的结构和过程，因此无法治愈病毒感染。
Using them against viruses adds selection pressure for resistance without benefit.
用抗生素对抗病毒只会增加耐药性选择压力，却毫无益处。
Pathogens cause infectious disease.
病原体导致传染病。
After vaccination, memory cells can support a faster secondary response.
接种疫苗后，记忆细胞可支持更快的二次免疫应答。
Watch for: antibiotics do not act on viruses in the same way they act on bacteria.
注意：抗生素对病毒的作用方式与对细菌不同。
Eight cases occur among five hundred people.
500人中有8例病例。
Find the rate per one thousand.
求每1000人的发病率。
A smaller case count can still be a higher rate.
较小的病例数仍可能对应较高的发病率。
The result is 16 cases per 1000.
结果是每1000人16例。
Group A has 18 cases in 900 people, which is 20 per thousand.
A组900人中有18例，即每千人20例。
Group B has fewer cases but a higher rate: 40 per thousand.
B组病例更少，但发病率更高：每千人40例。
Fictional samples report 12 cases in 600 people and 8 in 200.
虚构样本报告在600人中有12例，在200人中有8例。
Compare rates and identify what else is needed before concluding one exposure caused disease.
请比较感染率，并指出在得出一次暴露导致疾病的结论之前还需要什么其他信息。
The rates are 20 and 40 per 1,000.
两组的发病率分别是每千人 20 例和 40 例。
Compare time windows, definitions, sampling and confounders.
还要比较时间窗口、病例定义、抽样方法和混杂因素。
These proportions do not establish causation or an individual diagnosis.
这些比例并不能证明因果关系，也不能用于个人诊断。
Pause and check yourself. Explain each point on screen in your own words, then change one number in the last example and say which assumption must still hold.
暂停一下，自我检查：用自己的话解释屏幕上的每个要点，再改动最后一个例子中的一个数字，说明哪个假设仍然必须成立。