Persistent low fever for a week usually has three major systemic problems: i. Functional fever, when there is a persistent fever for a week during a woman’s ovulation period. Second, seasonal fever and environmental fever, a week has been working in a hot environment, or summer around the outside temperature is too high, can also cause persistent low fever for a week. Third, infectious factors, the most common are tuberculin infection, infection with tuberculosis and intestinal tuberculosis, there can be a week of continuous low-grade fever. IV. Chronic kidney disease, pyelonephritis, and chronic urinary tract infections can also cause continuous hypothermia for a week. V. Chronic connective tissue diseases such as rheumatic fever and chronic rheumatoid arthritis can also have continuous low fever for one week. Sixth, non-infectious diseases such as immune system hypofunction, tumors, and hematologic diseases can also last for one week with low fever.