How would you know if you are hepatitis b infectiousvor contagoius?

A simple blood test: Ur doctor can easily look for Hepatitis B infection through a blood test. The problem is, in the Philippines, many people were infected at birth, so they don't know they have the virus, until liver damage later in life catches up with them. Good to get tested by a doc. If there's Hepatitis B antigen (Hep Bs Ag) then that means infection. Good news is there's a vaccine if you are not yet protected.