Low fever is defined as a body temperature of 37.3°C to 38°C. A prolonged low fever is a fever that lasts for more than two weeks, excluding intermittent fevers. There are also many reasons for the development of hypothermia. It is mostly more stubborn. I. Etiology Fever is a symptom, rheumatism, tuberculosis, chronic inflammation, immune deficiency and other diseases can cause persistent low fever; long-term psychological tension and emotional instability can also cause disorders in the body temperature center, resulting in unexplained persistent low fever. Problems with any system of the body can cause persistent low fever. It is difficult to find out what the cause of low fever is through routine tests such as blood, urine and stool. Some low fevers caused by diseases with bacterial infections can only be found through bacterial culture. Second, examination Refers to a sustained fever of more than two weeks with a body temperature of 37.3℃~38℃. Timely examination of routine blood, chest X-ray, blood sedimentation, etc., as well as examination of bone marrow image, etc., if necessary, and dialectical treatment by the Chinese medicine department of the regular hospital is also possible, to determine the cause of the disease and so on should be the most critical, and to develop reasonable treatment measures according to the examination results. The most important thing is to determine the cause of the disease and to develop reasonable treatment measures based on the test results. Third, the differential diagnosis 1, repeated fever: bronchial foreign body clinical light, heavy varies, the length of the disease varies. If the disease is prolonged with secondary infection, fever, cough and wet rales can be heard in the lungs repeatedly. 2.Continuous fever: The normal body temperature of a person is about 36.5-37°, if it is higher than 37.2°, it is called fever. When a person cannot maintain a normal body temperature, many physiological functions will become impaired. Symptoms of Coxsackie virus in newborns: temperature over 38. 5°C,, depression or, irritability, persistent fever, shortness of breath, general weakness, rapid heartbeat, etc. Increased vomiting, even continuous vomiting or jet-like vomiting. Muscle twitching spasms or stiff neck and limbs, blurred consciousness or coma. IV. Prevention and treatment Unidentified low fever should not be abused. Fever is one of the reactions of the organism to resist disease attack. Low fever patients taking antipyretic drugs is not conducive to the treatment of the disease. The indiscriminate use of antipyretic drugs also leads to the risk of white blood cell decline and aplastic anemia. The use of antipyretics should be considered only when the body temperature is 38°C or higher. Persistent low fever should be seen by a doctor as early as possible and a thorough examination should be conducted early. Some early malignant tumors or early bacterial infections are also symptomatic of a low fever.