Hep A•high risk groups for HAV infection include international travelers, •users of injection and noninjection drugs, and men who have sex with men•Close contacts of infected individuals are also at risk•The secondary infection rate for hepatitis A virus in household contacts of patients with acute HAV infection is around 20%
Hep B•a member of the Hepadnaviridae family•doubled-stranded DNA virus•The viral core particle consists of a nucleocapsid, HBcAg, which surrounds HBV DNA, and DNA polymerase. •The nucleocapsid is coated with HBsAg. •The intact HBV virion is known as the Dane particle. •Dane particles and spheres and tubules containing only HBsAg are found in the blood of infected patients. •In contrast, HBcAg is not detected in the circulation but liver sections
Hep B•Readily detected in serum •very low levels in semen, vaginal mucus, saliva, and tears. •not detectable in urine, stool, or sweat. •HBV can survive storage at –20°C and heating at 60°C for 4 hours. •It is inactivated by heating at 100°C for 10 min or by washing with sodium hypochlorite (bleach)•reservoirs of HBV consists of people with chronic HBV infection.•In this group, those with HBeAg in their serum tend to have higher viral titers and thus greater infectivity
Hep BTransmition –both parenterally and sexually, –Saliva, serum, and semen all have been determined to be infectious.–Percutaneous exposures leading to the transmission of HBV include transfusion of blood or blood products,–injection drug use with shared needles, –hemodialysis, and needlesticks in health care workers.•Globally and in the United States, perinatal transmission is one of the major modes of transmission. •The greatest risk of perinatal transmission occurs in infants of HBeAg-positive women. •By age 6 months, these children have a 70-90% risk of infection, and of those who become infection, about 90% will go on to develop chronic infection with HBV.•For infants born to HBeAg-negative women, the risk of infection is approximately 10-40%, with a chronic infection rate of 40-70%.•Even if transmission does not occur in the perinatal period, these children are still at significant risk for the development of infection during early childhood
Hep BHigh risk groups for HBV infection •intravenous (IV) drug users, •persons born in endemic areas, and men who have sex with men •health care workers exposed to infected blood or bodily fluids, •recipients of multiple blood transfusions, •patients undergoing hemodialysis, •heterosexual persons with multiple partners or a history of sexually transmitted disease, •institutionalized persons (eg, prisoners), developmentally disabled persons, •household contacts or sexual partners of HBV carriers.
Hep C•HCV, a member of the Flaviviridae•It has 1 serotype, but at least 6 major genotypes and more than 80 subtypes are described•The wide genetic variability of HCV hampers the efforts of scientists to design an effective anti-HCV vaccine.