A、They contracted the disease by being with the infected people. B、They contracted the disease by breathing the contaminated dus

Health officials in Argentina are working to control the spread of a very serious sickness caused by a kind of virus—the Hantan Virus. The Hantan Virus leads to the Hantan Virus pulmonary syndrome. People become sick after they breathe the dust from the dried waste of the infected mice or rats.
    The sickness can not spread from one person to another. Signs of the sickness include high fever , headaches and pain in muscles and joints. The virus destroys lung tissue very quickly and the victims soon become unable to breathe. But people treated with drugs can survive. The victims must be treated quickly, however, after the first signs of the disease appear. One problem is that people think they have a cold and not to seek treatment until it’ s too late. At least 12 people were infected with the disease in Argentina in 1996, and 7 people died. Health officials are concerned about the number of death.
    People in other South American countries have suffered from the Hantan Virus disease in recent years including Brazil and Paraguay. But only one or two people a year died from the virus.
    Health officials in Argentina believe their citizens were infected in the south of the country— the popular holiday area. They say the virus has probably existed for years in one kind of wild rats. But now some environmental changes have forced the rats into the areas where people live and this has caused the increasing number of the infections.
21. According to the speech, how do people contract the disease?
22. Which of the following is not the sign of the sickness?
23. Why have so many people died from the disease?
24. What has caused the increasing number of infections?
25. Which country isn’ t referred in the passage who have suffered from the Hantan Virus disease?