What should you know about occult hepatitis B infection?

Occult infection can be identified through a combination of hepatitis B blood markers and a test for viral genetic material. Results need careful interpretation because antibodies, surface antigen, and viral levels can vary over time. A negative surface antigen does not by itself answer every question about past or current infection.

The finding is especially relevant before treatments that weaken or alter the immune system, including some cancer therapies. Such treatment can allow hepatitis B to become active again. This is called reactivation and may affect the liver, so the oncology and liver teams may coordinate monitoring or preventive antiviral treatment.

Ask which hepatitis B tests were positive, whether viral genetic material was detected, and whether liver blood tests need repeating. Tell every doctor about the result before starting chemotherapy, immunotherapy, steroids, or another immune-altering treatment. Do not start or stop antiviral medicine without the prescribing clinician’s advice. Household and sexual contacts can ask a clinician whether testing or hepatitis B vaccination is appropriate.

Contact your healthcare team promptly for yellowing of the eyes or skin, dark urine, pale stools, persistent vomiting, increasing abdominal swelling, unusual sleepiness, or confusion. Seek urgent care for severe confusion, vomiting blood, collapse, or severe abdominal pain. These symptoms can have several causes but may signal serious liver illness.

Ask whether the infection is active or occult, whether viral genetic material was detected, how liver function will be monitored, whether cancer treatment changes the plan, and whether family or household contacts need testing or vaccination.