hbsag is the hbv virus and infection is cronic if hbsag is positve for more than 6 months (hbsag is the surface antigen of the virus)
but presence of virus and cronic infection doesn't mean active disease and liver damage, there are many phases of infection and any phase can be life long, probably your wife has inactive disease so doctor said you don't need to worry
how to know phase?hbv markers:
hbsag -(much better with quantification by abbott hbsag quantity test in iu/ml, other units are useless)
hbeag and hbeab
hbcab and hbcab
hbvdna pcr
alt/ast
how to detect liver damage if any?
ultrasound, fibroscan (if alt not higher than 200)
liver function test
ultrasound must be made every 6 weeks because hbsag positive makes higher rates of liver cancer than pepole with hbsag negative, athough percentage is very low (don't remember but between 1-5%) it is better to check for prevention
as to therapies:
http://www.medhelp.org/health_pages/Hepatitis/HepB-Introduction--Welcome-Page/show/34?cid=153
as to inactive disease:
hbsag lower than 1500iu/ml, usually hbeab positive, normal alt/ast (for woman less than 19), f0-f1 liver damage, monitor every 3-6months alt/ast, hbvdna
as to inactive carrier:
hbsag lower than 500iu/ml, hbvdna undetactable or very low