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Английский язык
от ddasa3599
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For thousands of years, there were no epidemic diseases. However, when people started living in towns, infections could spread more easily. When traders and armies travelled from city to city, they brought bacteria and viruses with them and spread infections to new populations. Children were in the greatest danger: in the nineteenth century, 50% of children died before the age of five. Most infections are spread in the same way: bacteria or viruses are passed on by coughing, sneezing or by touching food with infected hands. People began to understand this as early as the 1300s. During the plague in Milan, the streets were regularly cleaned and the clothes of plague victims were burned. In the nineteenth century, Ignaz Semmelweiss observed that infection was spread by doctors' dirty hands and recommended washing hands before touching patients. Another early way of avoiding disease was quarantine-sick people were isolated from healthy ones. Vaccines were first used in the eighteenth century. In 1796, Edward Jenner vaccinated people against smallpox. Nowadays, in many countries, common diseases, such as measles or TB.