As you already mentioned the only tests determining the need for treatment are the HBV DNA
PCR Quantitative titre and the liver
enzymes namely the AST & ALT
. I do not know of any country that would bar anyone with Hepatitis B
either carrier or any other state from entering.
Hope I have answered your query and your son stays well. I will be available in case of any further queries.
Dr. Prashantha S. Rao