Health Care and Epidemics (流行病) Everyone suffers from disease at some time or another. However, millions of people around the world do not have good health care. Sometimes they have no money to pay for medical treatment. Sometimes they have money, but there is no doctor. Sometimes the doctor does not know how to treat the disease, and sometimes there is no treatment. Some people are afraid of doctors. When these conditions are present in large population centers, epidemics can start. Epidemics can change history. Explorations and wars cause different groups of people to come into contact with other. They carry strange disease to each other. For example, when the Europeans first came to North and South America, they brought diseases with them that killed about 95 percent of the Native American population. People are very afraid of unknown things, especially diseases. People have all kinds of ideas about how to prevent and treat disease. Some people think that if you eat lots of onions or garlic, you won' t get sick. Others say you should take huge amounts of vitamins. Scientific experiments have not proved most of these theories. However, people still spend millions of dollars on vitamins and other probably useless treatments or preventatives. Some people want antibiotics whenever they get sick. Some antibiotics are very expensive. Much of this money is wasted because some diseases are caused by a virus. Viruses are even smaller than bacteria, and they cause different kinds of diseases. Antibiotics are useless against viruses. Because of their fear, people can be cruel to victims of disease. Sometimes they fire them from their jobs, throw them out of their apartments, and refuse them transportation services. In the plague (瘟疫) epidemics a few hundred years ago, people simply covered the doors and windows of the victim' s houses and left them to die inside, all in an effort to protect themselves from getting sick. Doctors know how most epidemic diseases spread. Some, like tuberculosis, are spread when people' s sneeze (喷嚏) sends the bacteria shooting out into the air. Then they enter the mouth or nose of anyone nearby. Others are spread through human contact, such as on the hands. When you are sick and blow your nose, you get viruses or bacteria on your hands. Then you touch another person' s hand, and when that person touches his or her mouth, nose, or eyes, the disease enters the body. Some diseases spread when people touch the same dishes, towels, and furniture. You can pick up a disease when you touch things in public buildings. Other diseases are spread through insects such as flies, mosquitoes, and ticks. One disease that causes frequent, worldwide epidemics is influenza, or flu for short. The symptoms (症状) of influenza include headache and sometimes a runny nose. Some victims get sick to their stomachs. These symptoms are similar to symptoms of other, milder diseases. Influenza can be a much more serious disease, especially for pregnant women, people over sixty-five, and people already suffering from another disease, such as heart problems. About half of all flu patients have a high body temperature, called a fever. Flu is very contagious. One person catches the flu from another person it doesn't begin inside the body as heart disease does. Sometimes medicine can relieve the symptoms. That is, it can make a person cough less, make headaches less intense, and stop noses from running for a while. However, medicine can ' t always cure the disease. So far, there is no cure for many diseases and no medicine to prevent them. People have to try to prevent them in other ways. Some diseases can be prevented by vaccination (接种疫苗). A liquid vaccine is injected into the arm or taken by mouth and the person is safe from catching that