Fever is a common symptom in patients with infectious diseases. This study hopes to understand the epidemiological characteristics of patients hospitalized due to fever through observational research, including: clinical characteristics, etiology of fever and prognosis after treatment. So as to further search for biochemical or other serological indicators to predict the diagnosis and prognosis of infectious fever and non-infectious fever, and try to establish relevant prediction models.

This study mainly prospectively analyze the clinical data of patients with fever with/without other symptoms admitted to the department of infectious diseases, Xiangya Hospital of Central South University, to analyze the epidemiological characteristics, diagnosis and prognosis of these patients. This is an observational study. All subjects will receive the currently recognized routine test of fever according to their disease and corresponding etiological treatment if needed. The researchers will collect various clinical examination indexes of the subjects in the process of diagnosis and treatment, including but not limited to white blood cells, C-reactive protein, Procalcitonin, ferritin, blood culture, therapeutic drugs, etc. Etiology and prognosis of patients will be recorded. Blood samples, urine and stool samples of all subjects will be taken after enrollment and stored for probably testing in the future. This study has no additional intervention and treatment for subjects. All subjects will sign informed consent.

Inclusion Criteria:

• all patients admitted to department of infectious diseases because of fever

Exclusion Criteria:

• patents who refuse to sign informed consent

Patients between the age of 14-90, who were admitted to Department of Infectious Diseases because of fever with/without other symptoms were all elligible for this observational study.