Class B infectious diseases are strictly managed infectious diseases. Currently, our country divides infectious diseases into three categories, mainly Class A, Class B and Class C. Category A infections are mainly plague and cholera, which are virulent infectious diseases under mandatory management. There are 25 types of Class B infectious diseases, such as SARS, viral hepatitis, epidemic hemorrhagic fever, rabies, epidemic B encephalitis, whooping cough, scarlet fever, bacillary dysentery, tuberculosis, etc. These are all Class B infectious diseases, which require direct reporting on the network within six hours after discovery in towns and cities, and within 12 hours in rural areas. There is also a category C infectious diseases, there are currently 12, which require reporting within twenty-four hours of discovery.