Hello, Having jaundice four years back could have been either hepatitis B virus or any other virus. You must have developed the virus now, if u had no history of it. Once your Hbsag status is positive , please consult your Gastroenterologist , so that he can advice you further tests to know if the disease is active or not (hbeAg), whether your body have developed immunity against the virus or not ( Igm anti HBe), and how much is the viral load at present (HBV DNA- quantitative analysis) , with USG abdomen to see your liver status , only Dependimg on these parameters can anyone decide if treatment should be started or do you just need regular follow to know the viral status, and Hepatitis B virus spreads via bodily fluids, please ask everyone in your family to be evaluated and if they are negative for the virus, let them get vaccinated immediately , but anyone is positive they should go about it the same way as yours, hence please consult your Gastroenterologist and get yourself completely evaluated. Hope I could help you. Thank you.