By Brundage, Stephanie C; Fitzpatrick, A Nicole
The introduction of hepatitis A vaccines in 1995 led to a drop in the number of reported cases of hepatitis A and a shift to a higher percentage of cases occurring in older age groups. The hepatitis A virus survives for extended periods in the environment. Transmission primarily is fecal-oral, although there have been rare instances of transmission through blood products. The virus appears sporadically and is spread by close personal contact, with occasional food-borne outbreaks. Older persons infected by the virus usually develop a symptomatic infection with abrupt onset, fever, and jaundice lasting two months. Children usually have an asymptomatic infection and rarely develop jaundice. Laboratory diagnosis is made by detection of antihepatitis A virus immunoglobulin M in serum. Ten to 20 percent of symptomatic patients experience a prolonged or relapsing course of illness, but chronic infection has not been reported. Fulminant infection occurs in less than 1 percent of patients and can result in emergent liver transplant or death. Prevention starts with thorough handwashing and careful food handling. Prompt disease reporting, the identification of exposed persons, and expeditious administration of immune globulin prevent secondary transmission of the disease. Physicians should consider routine vaccination of children 12 to 23 months of age based on recommendations from the Centers for Disease Control and Prevention. Vaccination for children two years or older and adults should be included in routine preventive care for those at increased risk of contracting the disease (e.g., travelers to certain countries, men who have sex with men, drug abusers, recipients of clotting factor replacement) and for persons with chronic liver disease. (Am Fam Physician 2006;73:2162-8, 2169-70. Copyright 2006 American Academy of Family Physicians.)
Targeted use of hepatitis A vaccines in the United States since 1995 has led to a dramatic decrease in the number of reported cases of hepatitis A, from 32,000 in 1990 to 7,700 in 2003,1 with most of the decrease occurring in children.2 As a result of this trend and new cost-effectiveness data, the Advisory Committee on Immunization Practices (ACIP) has recommended vaccination against hepatitis A virus for all children during routine immunization at the age of 12 to 23 months.3 With the strategy of universal vaccination, the disease could potentially be eradicated in the United States.
Even before the targeted use of the vaccine, good sanitation practices resulted in a generally low incidence of hepatitis A in the United States, with a correspondingly low overall immunity rate of about 33 percent.4 This low population immunity creates the potential for epidemics of symptomatic disease resulting from food- or water-borne transmission, such as that which occurred in four eastern states in 2003 caused by imported contaminated raw green onions in restaurant salsa.5REFERENCES
1. Centers for Disease Control and Prevention. Reported cases of acute viral hepatitis, by type and year, United States, 1966-2003. Accessed March 2, 2006, at: http://www.cdc.gov/ncidod/diseases/ hepatitis/resource/pdfs/surv_table.pdf.
2. Wasley A, Samandari T, Bell BP. Incidence of hepatitis A in the United States in the era of vaccination. JAMA 2005;294:194-201.
3. Fiore AE, Wasley A, Bell BP, for the Advisory Committee on Immunization Practices. Prevention of Hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55(RR-7):1-23.
4. Cuthbert JA. Hepatitis A: old and new [Published correction appears in Clin Microbiol Rev 2001;14:642]. Clin Microbiol Rev 2001;14:38-58.
5. Centers for Disease Control and Prevention. Hepatitis A outbreak associated with green onions at a restaurant-Monaca, Pennsylvania, 2003. MMWR Morb Mortal Wkly Rep 2003;52:1155-7.
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