and food.It is an illness caused by the bacterium called Vibrio cholera.It produces an enterotoxin that causes painless，watery diarrhea that can quickly lead to severe dehydration and death if treatment is not given.Most people infected with cholera do not become ill，although the bacterium is present in their wastes for 7～14 days.When cholera does 话题语篇导读 happen，more than 90% of cases are not severe and are difficult to tell from other types of diarrhea.Less than 10% of ill people develop cholera with signs of moderate or severe dehydration.

　　A person may get cholera by drinking water or eating food polluted with the cholera bacterium.The disease can spread rapidly in areas without proper treatment of drinking water.The cholera bacterium may also live in the environment in dirty rivers and coastal waters.Shellfish eaten raw can be a source of cholera.The disease is not likely to spread directly from one person to another，therefore.

　　Cholera can be simply and successfully treated by immediate replacement of the fluid and salts lost through diarrhea.Patients can be treated by being given a mixture of sugar and salt to be mixed with water and drunk in large amounts.People who develop severe diarrhea in countries where cholera breaks out should seek medical attention at once.

　　In a word，to avoid cholera，we should develop a good habit.We should eat well-­cooked food instead of raw food. Task

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