Headache, nausea and low fever are generally common in two cases: first, there are other parts of the infection causing vascular headache, also known as post-fever headache, this kind of headache is a functional headache, there is no inflammation in the central nervous system as well as organic lesions, it is a headache secondary to infection in other parts of the body, such as upper respiratory tract infection, digestive tract infection, causing fever; second, central nervous system infection, there is central nervous Second, central nervous system infection, which is a central nervous system inflammation, is generally a viral infection, bacterial infection or Mycobacterium tuberculosis infection is the most common, and less common are parasitic and fungal infections, which can cause headache, nausea, vomiting, positive meningeal irritation signs, of which Mycobacterium tuberculosis infection generally fever is most common with low fever, often below 38.5℃.