Hepatitis

Symptoms are similar to those manifested by HAV and may include weight loss, muscle aches, headaches, flu-like symptoms, mild temperature elevation, and constipation or diarrhea. By the time jaundice appears, which is often quite noticeable and prolonged in older women, the patient may feel somewhat better overall but the urine becomes dark, stools light or yellowish, the liver and possibly the spleen enlarged and painful, and fluid may accumulate around the abdominal area. Early in the disease's life, however, symptoms may be very slight or even virtually nonexistent—particularly in children—facilitating infection of others before isolation is implemented.

The incubation period for HBV varies widely—any-where from four weeks to six months. Primary routes of transmission are blood or blood product transfusion; body fluids such as semen, blood, and saliva (including a bite by an infected human); organ and/or tissue transplants; contaminated needles and syringes in hospitals or clinical settings; contaminated needles or syringes in illegal intravenous drug use; and "vertical" transmission-from mother to baby during pregnancy, birth, or after birth through breast milk. Even though they may not develop symptoms of the disease during childhood, and will remain healthy, almost all infected newborns become "chronic carriers," capable of spreading the disease. Many of these infected yet apparently healthy children—particularly the males—will develop cirrhosis and liver cancer in adulthood. Where the incidence of the disease is relatively low, the primary mode of transmission appears to be sexual and strongly related to multiple sex partners, particularly in homosexual men. In locations where disease prevalence is high, the most common form of transmission is from mother to infant.