A protracted or relapsing course may develop in 10% to 15% of cases of HAV in adults, lasting up to 6 months with an undulating course before eventual clinical resolution. Fulminant hepatitis with encephalopathy, gastrointestinal bleeding from esophageal varices or coagulopathy, and profound jaundice is uncommon but is associated with a high mortality rate.
Most cases of acute viral hepatitis resolve without specific therapy, with less than 0.1% of cases progressing to fulminant hepatic necrosis. HAV and HEV cause acute infection only. HBV, HCV, and HDV may persist as chronic infection with chronic inflammation, fibrosis, and cirrhosis and the associated risk of hepatocellular carcinoma.
From 5% to 10% of adults with HBV develop persistent infection, defined by persistence of HBsAg in the blood for more than 6 months, compared with 90% of children who acquire HBV by perinatal transmission. Chronic HBsAg carriers are usually HBeAg-negative and have no clinical, biochemical, or serologic evidence of active hepatitis, unless there is superinfection with HDV. Approximately 10% to 15% of HBsAg carriers eventually clear HBsAg.
Approximately 85% of persons infected with HCV remain chronically infected, which is characterized by fluctuating transaminase levels (see Fig. 113-1). There is poor correlation of symptoms with ongoing liver damage. Approximately 20% of persons with chronic infection develop cirrhosis, and approximately 25% of those develop hepatocellular carcinoma. HIV infection and ethanol use increase the risk of HCV progression.
Good hygienic practices significantly reduce the risk of fecal-oral transmission of HAV. Screening blood donors for evidence of hepatitis significantly reduces the risk of blood-borne transmission. Specific postexposure measures are recommended to prevent secondary cases in susceptible persons.
HAV vaccine is recommended for routine immunization of all children beginning at 12 months and for unvaccinatedolder children in areas with targeted vaccination programs.Unvaccinated household and sexual contacts of persons withHAV should receive postexposure prophylaxis as soon as possible and within 2 weeks of the last exposure. A single doseof HAV vaccine at the age-appropriate dose is preferred forpersons 12 months to 40 years of age. Immunoglobulin (0.02mL/kg) given intramuscularly is preferred for children under12 months of age, persons over 40 years of age, and immunocompromised persons. Unvaccinated travelers to endemicregions should receive a single dose of HAV vaccine administered at any time before departure.