Are you sure you mean Hep B?
This is from a Dubai website (not copywrighted)
HEPATITIS B - This is the most common form of Hepatitis and is extremely unpredictable. The disease can take hold rapidly and result in a quick death. It also increases the risk of death due to cirrhosis or liver cancer. Spread through sexual intercourse or intravenous drug use, it is 100 times more infectious than AIDS and can be transmitted simply by kissing or sharing a toothbrush, cigarette or sheesha.
Symptoms - The same as Hepatitis A.
Source of infection - It spreads from mother to child at birth or soon after birth. Through sexual contact, blood transfusions or contaminated needles.
The blood test in the medical for a visa is designed largely to check for HIV/AIDS, but I don't see this going down well. In addition it is infectious and the government wishes to exclude all infectious diseases.