Pandemic, epidemic, endemic和plague都有“流行病”的含义。但是这四个表达不能替换，有所区别，以下做具体介绍：

Pandemic: 大流行病。根据世界卫生组织的定义，大流行病是“一种蔓延至全世界，或跨越国界，蔓延至极广泛区域，通常影响大量人群的流行病。”A pandemic is an occurrence of a disease that affects many people over a very wide area.

Epidemic：是较为客观的说法，相当于“流行病”，常做医学术语，指的是在某个社区或者城市，同时出现某种疾病的大量病例。

Endemic：常指的是“地方病”，地方性（某地或某集体中）特有的疾病。

Plague：一般指“鼠疫；瘟疫”，Plague or the plague is a very infectious disease that usually results in death. The patient has a severe fever and swellings on his or her body，也指某种不好的事物或者情况大量出现，作比喻使用。

以下提供对应参考双语例句进一步理解这四个词汇的差别：

①However, some of those proposals have been superseded as a result of subsequent events and the emergence of new requirements, in particular the establishment of a central business continuity management unit to address business continuity issues on a broader, Organization-wide basis, taking into account pandemic planning and other non-information and communications technology aspects (see A/64/472 and document A/64/7/Add.8 in the present supplement), as well as the requirement for a new secondary data centre in the context of the relocations due to the capital master plan (see A/64/346/Add.1).

然而，其中一些建议由于之后的活动和新的所需条件的出现，尤其是业务连续性中央管理股的设立而时过境迁，该 股的目的是在全联合国更广泛的基础上处理业务连续性问题，同时考虑 到预防大流行病规划和其 他非信息和通信技术方面(见A/64/472和本补编第A/64/7/Add.8号文件)，以及在因基本建设总计划而引起迁移的情况下建立1个新的二级数据中心的需要(见 A/64/346/Add.1)。

②Further action taken to strengthen harmonized activity include a series of subregional consultations and capacity-building workshops with ministries of education and other key Education Sector stakeholders’ responses to the epidemic, and supporting the inclusion of the Education Sector in HIV and AIDS-related country coordinating mechanisms. 

采取的加强协作的进一步行动包括在教育行业应对艾滋病的工作以及教育部和其他关键利益相关方举行一系列次区域磋商和能力建设讲习班，支持将教育部门纳入与艾滋病毒和艾滋病相关的国家协调机制。

③The Executive Director of UNICEF added that the potential to eliminate malaria as a public-health problem in most malaria-endemic countries and to virtually eliminate PMTCT over the next few years was a truly historic opportunity that should motivate the international community to work more closely together. 

儿基会执行主任补充说，在大多数疟疾流行的国家消灭疟疾这一公共卫生问题和在今后几年内杜绝艾滋病母婴传播的可能性，是一个真正的历史性机遇，国际社会应为此更加密切地合作。

④WHO also uses geospatial information in its programmes for specific diseases, such as Rift Valley fever, meningitis, yellow fever, cholera, the plague and leptospirosis to develop a decision-support tool and inform the current vaccination strategies. 

世卫组织还在其针对特定疾病的方案中利用地球空间信息，如里夫特裂谷热、脑膜炎、黄热病、霍乱、瘟疫和细螺旋体病，以开发决策支助工具，并为当前的疫苗战略提供信息依据。