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  3. Disease and History P1: Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease condit

Disease and History P1: Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease condit

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问题 Disease and History
P1: Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. In 1971, anthropologist Abdel Omran outlined three trends in the relationship between diseases and the human species and referred to them as the three "epidemiological transitions." For nearly four million years, humans lived in widely dispersed, nomadic, small populations that minimized the effect of infectious diseases. Early human ancestors must have suffered from new diseases every time they built a settlement in new surroundings. Infectious disease may not have had serious effects on large numbers of people or many different populations, however, since diseases would have had little chance of being passed on to many other humans.
P2: The first epidemiological transition occurred approximately 10,000 years ago, when early societies started to supplement existing food sources with domestication of some plants and animals after their migration. Increasing sedentism and population density resulted in the first widespread infectious and nutritional diseases. Animal domestication may have brought people into contact with new diseases previously limited to other species. Working the soil would have exposed farmers to insects and other pathogens. Irrigation in some areas provided breeding places for mosquitoes, increasing the incidence of malaria and other mosquito-borne diseases. Sanitation problems caused by larger, more sedentary populations would have helped transmit diseases in human waste, as would the use of animal dung for fertilizer. Besides, the emergence of pre-agriculture also led to a relatively narrow selection of food sources, as compared to the varied diets of their nomadic counterparts, whose food was mainly derived from hunting and gathering. This could have led to nutritional deficiencies. Finally, the storage of food surpluses attracted new disease carriers such as insects and rodents. Trade between settled communities helped spread diseases over large geographic areas, as in the case of the Black Death in Europe. Epidemics, in the sense of diseases that impact a great number of populations simultaneously, were essentially nonexistent until the development of agricultural economies.
P3: The second epidemiological transition commenced at the end of the nineteenth century and extended to the twentieth, involving improvements in nutrition, public health, and medicine. Many infectious diseases were finally brought under control or even eliminated during the second phase. There was a shift from acute infectious diseases to chronic non-infectious, degenerative diseases. The increasing prevalence of these chronic diseases was related to an increase in longevity; cultural advances resulted in a larger percentage of individuals reaching the oldest age segment of the population. In addition, many of these diseases shared common etiological factors related to an increasingly sedentary lifestyle, leading to less physical activity, more mental stress, high-fat diets, and environmental pollution.
P4: However, on the heels of the second transition had came the third epidemiological transition, which dominates contemporary society. New diseases are emerging and old ones are returning. The emergence of infectious disease with multiple forms of antibiotic resistance has been one of the most intriguing evolutionary stories of the last decade. Researchers have identified more than two dozen novel pathogens and grappled with the evolution of antibiotic-resistant microbes in the past three decades. This evolution may have been encouraged by what some authorities consider an overuse of antibiotics, giving microorganisms a greater chance to evolve resistance by exposing them to a constant barrage of selective challenges. Some bacteria reproduce hourly, and so the processes of genetic mutation and natural selection are greatly sped up in these species.
P5: The engine that is driving the reemergence of many kinds of disease is ecological change that brings humans into contact with pathogens. As people and their products became more mobile, and as human populations spread into previously little-inhabited areas, cutting down forests and otherwise altering ecological conditions, we come into contact with other species that may carry diseases to which they are immune but that prove deadly to us. This presents a significant challenge to the countries facing a dual burden of infectious and chronic diseases.
P2: The first epidemiological transition occurred approximately 10,000 years ago, when early societies started to supplement existing food sources with domestication of some plants and animals after their migration.■ Increasing sedentism and population density resulted in the first widespread infectious and nutritional diseases. ■ Animal domestication may have brought people into contact with new diseases previously limited to other species.■ Working the soil would have exposed farmers to insects and other pathogens. ■ Irrigation in some areas provided breeding places for mosquitoes, increasing the incidence of malaria and other mosquito-borne diseases. Sanitation problems caused by larger, more sedentary populations would have helped transmit diseases in human waste, as would the use of animal dung for fertilizer. Besides, the emergence of pre-agriculture also led to a relatively narrow selection of food sources, as compared to the varied diets of their nomadic counterparts, whose food was mainly derived from hunting and gathering. This could have led to nutritional deficiencies; finally, the storage of food surpluses attracted new disease carriers such as insects and rodents. Trade between settled communities helped spread diseases over large geographic areas, as in the case of the Black Death in Europe. Epidemics, in the sense of diseases that impact a great number of populations simultaneously, were essentially nonexistent until the development of agricultural economies.
Why does the author state that "many infectious diseases were finally brought under control"?
选项 A、To present evidence for infectious diseases bringing death to us
B、To clarify why the second epidemiological transition took place in 19th century
C、To contrast with a shift from infectious diseases to chronic diseases
D、To indicate that modern medical science provides better public health measures and improved nutrition
答案C
解析 【修辞目的题】本段的重心是交代the second epidemiological transition，因此提到…under control是为下文的转变作铺垫。
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