Patient: I have low fever since June, 36.7~37.3 before ovulation, 37.1~37.7 after ovulation, the highest temperature occurs between 5pm and 6pm, blood count, C-reactive protein, rheumatoid factor, anti-o are normal, thyroid is normal, Ptd test, the reactive red mass on my arm is larger than 2cm, but it is not broken, the doctor said it is a normal reaction to BCG vaccination. No abnormalities were found in the routine physical examination, what should I do? Low fever definitely indicates that there is something wrong with the body, but what is the problem, it is confusing. If there is a virus in the body, how can I find out? Answer: The normal PPD test usually does not exceed 2cm. Even if you have been vaccinated with BCG, those who exceed 2cm are strongly positive for PPD test and should consider the possibility of TB infection. Please check further lung CT and T-SPOT-TB. Patient: Thank you for replying so quickly! If it is tuberculosis, can’t the blood picture be seen? Response: It can be seen without it. Patient: T-SPOT-TB is normal, but cytomegalovirus IgM is found to be positive, which is probably the cause of my low fever. Thank you, Dr. Ye! Reply: You are welcome. Patient: Dr. Ye: My cytomegalovirus is positive. Chaoyang Hospital prescribed me with Acyclovir tablets, Jinhua Qingxian, and Guaifen Fever Reducing Spirit, but I haven’t seen any improvement after taking them for 2 days. Reply: Change to intravenous ganciclovir to see. Patient: Good, listen to your advice, thank you!