Hepatitis B is a highly infectious disease which attacks the liver, & is more serious than Hepatitis A. It can be acute (short-term, lasting for months), or chronic (persisting for years). It is recommended for travel because it can be transmitted through non-sterile medical, dental, or tattooing equipment, & because it is highly infectious & can live outside of the body for up to seven days. Vaccination is also recommended for healthcare professionals, since it can be transmitted through exposure to the blood & body fluids of an infected person.