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Globalization, the flow of information, goods, capital and people across political and geographic boundaries, has helped spread some of the deadliest infectious diseases known to humans.〔 〕 The spread of diseases across wide geographic scales has increased through history. Early diseases that spread from Asia to Europe were bubonic plague, influenza of various types, and similar infectious disease. In the current era of globalization, the world is more interdependent than at any other time. Efficient and inexpensive transportation has left few places inaccessible, and increased global trade in agricultural products has brought more and more people into contact with animal diseases that have subsequently jumped species barriers (see zoonosis).〔http://www.richardwellsresearch.com/richardwells/pdfs%20and%20documents/BJIC%20Oct〕 Globalization intensified during the Age of Exploration, but trading routes had long been established between Asia and Europe, along which diseases were also transmitted. An increase in travel has helped spread diseases to natives of lands who had not previously been exposed. When a native population is infected with a new disease, where they have not developed antibodies through generations of previous exposure, the new disease tends to run rampant within the population. Etiology, the modern branch of science that deals with the causes of infectious disease, recognizes five major modes of disease transmission: airborne, waterborne, bloodborne, by direct contact, and through vector (insects or other creatures that carry germs from one species to another). As humans began traveling over seas and across lands which were previously isolated, research suggests that diseases have been spread by all five transmission modes. ==Travel patterns and globalization== The Age of Exploration generally refers to the period between the 15th and 17th centuries. During this time, technological advances in shipbuilding and navigation made it easier for nations to explore outside previous boundaries. Globalization has had many benefits, for example, new products to Europeans were discovered, such as tea, silk and sugar when Europeans developed new trade routes around Africa to India and the Spice Islands, Asia, and eventually running to the Americas. In addition to trading in goods, many nations began to trade in slavery. Trading in slaves was another way by which diseases were carried to new locations and peoples, for instance, from sub-Saharan Africa to the Caribbean and the Americas. During this time, different societies began to integrate, increasing the concentration of humans and animals in certain places, which led to the emergence of new diseases as some jumped in mutation from animals to humans. During this time sorcerers' and witch doctors' treatment of disease was often focused on magic and religion, and healing the entire body and soul, rather than focusing on a few symptoms like modern medicine. Early medicine often included the use of herbs and meditation. Based on archeological evidence, some prehistoric practitioners in both Europe and South America used trephining, making a hole in the skull to release illness.〔“One curious method of providing the disease with means of escape from the body was by making a hole, 2.5 to five centimeters across, in the skull of the victim—the practice of trepanning, or trephining. Trepanned skulls of prehistoric date have been found in Britain, France, and other parts of Europe and in Peru. Many of them show evidence of healing and, presumably, of the patient's survival. The practice still exists among primitive people in parts of Algeria, in Melanesia, and perhaps elsewhere, though it is fast becoming extinct. "Medicine, History of", (2006), in ''Encyclopædia Britannica''. Retrieved November 22, 2006, from Encyclopædia Britannica Online: http://www.search.eb.com/eb/article-35642〕 Severe diseases were often thought of as supernatural or magical. The result of the introduction of Eurasian diseases to the Americas was that many more native peoples were killed by disease and germs than by the colonists' use of guns or other weapons. Scholars estimate that over a period of four centuries, epidemic diseases wiped out as much as 90 percent of the American indigenous populations.〔 In Europe during the age of exploration, diseases such as smallpox, measles and tuberculosis (TB) had already been introduced centuries before through trade with Asia and Africa. People had developed some antibodies to these and other diseases from the Eurasian continent. When the Europeans traveled to new lands, they carried these diseases with them. (Note: Scholars believe TB was already endemic in the Americas.) When such diseases were introduced for the first time to new populations of humans, the effects on the native populations were widespread and deadly. The Columbian Exchange, referring to Christopher Columbus's first contact with the native peoples of the Caribbean, began the trade of animals, and plants, and unwittingly began an exchange of diseases.〔 It was not until the 1800s that humans began to recognize the existence and role of germs and microbes in relation to disease. Although many thinkers had ideas about germs, it was not until Louis Pasteur spread his theory about germs, and the need for washing hands and maintaining sanitation (particularly in medical practice), that anyone listened. Many people were quite skeptical, but on May 22, 1881 Pasteur persuasively demonstrated the validity of his germ theory of disease with an early example of vaccination. The anthrax vaccine was administered to 25 sheep while another 25 were used as a control. On May 31, 1881 all of the sheep were exposed to anthrax. While every sheep in the control group died, each of the vaccinated sheep survived. Pasteur’s experiment would become a milestone in disease prevention. His findings, in conjunction with other vaccines that followed, changed the way globalization affected the world. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Globalization and disease」の詳細全文を読む スポンサード リンク
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