Routine blood tests are generally not accurate in detecting infectious diseases. Blood tests are usually used to detect some hematologic diseases or to make a preliminary judgment on some common infections. Routine blood test is mainly to check and analyze some white blood cells, blood red blood cells, etc., and different infectious disease monitoring standards and data have different requirements and differences, so the routine blood test can not accurately indicate the status of infectious diseases. Instead, routine blood tests are mainly used to detect hematologic diseases, such as anemia and leukemia. In addition, some common infectious diseases may cause changes in the neutrophils and lymphocytes in the blood, so routine blood tests can also help physicians make preliminary judgments about the condition. Therefore, if you want to be tested for infectious diseases, you should under the guidance of a professional doctor take a special test, such as the four tests for infectious diseases, or a test for a certain kind of infectious disease, such as the five tests for Hepatitis B.