How does Huck convince the men looking for runaway slaves not to search the raft?

Huck tells the men searching for runaway slaves that he is thankful that someone will finally help him.  He says that his family is in the raft and that they have smallpox. The people that were supposed to search the raft are so afraid to get smallpox that they don't want to look in it.  They give Huck some money and tell him to go to the next town and try to get a doctor to help heal his familiy.