Hello Thanks for posting your query on Healthcare Magic ESR - Erythrocyte Sedimentation rate means how fast the erythrocyte (Red Blood Cells) move with gravity towards the bottom and this rate of fall is determined by viscosity of blood which actually varies according to different protein substance present in it. Many diseases (including chronic inflammation) produce antibodies and other inflammatory products. They are responsible for increase in viscosity of blood in tern increases ESR This very old method of laboratory to make the diagnosis of different diseases and after so many advances in technology it is still being used because of very simple easily available and of course cheap test. In practice we use for screening many diseases like tuberculosis, connective tissue disorders but more commonly used in follow up to assess direction of therapy. Increased ESR in isolation does not give much information in may increase in the absent of disease even post operated patient may have high ESR Regarding your illness i can be due to viral fever later on it may be complicated by bacterial infection but not always. In Endemic (where disease is prevalent area of tuberculosis (like India) evening rise of temperature in the person should be evaluated for tuberculosis....I mean persistent evening rise not for few days. So if not in endemic area wait for some days Hope this answers your query. If you have additional questions or follow up queries then please do not hesitate in writing to us. I will be happy to answer your queries