![]() ![]() Once ingested orally, the virus is taken up from the gastrointestinal tract and the HAV particles are carried to the basolateral membrane of the hepatocyte via the portal circulation. Animal studies showing HAV antigen in the epithelial cells of intestinal crypts and cells of the lamina propria in the small intestine suggest replication might also occur at these sites. It is a positive-sense, single-stranded RNA virus which replicates primarily within hepatocytes. ![]() HAV, first identified in 1973 by Feinstone et al., is classified in the family Picornaviridae and genus Hepatovirus. Mortality from fulminant hepatic failure increases with increasing age. With increasing age symptomatic disease and adverse sequelae increases. It is most common in aid workers, gays, and around sewage. Acquisition often occurs in childhood, and it is usually asymptomatic. HAV is highest in resource-poor regions such as Africa, Asia, and South America, where evidence of past infection is nearly universal. Virtually any food may be contaminated with HAV. These groups include foreign travelers to developing nations, gays, childcare workers, institutionalized individuals, and those living in poverty.įood handlers are an infrequent source of outbreaks in the United States. Individuals in high-risk populations account for most cases of HAV infection. The greatest reductions are seen in children and in those states where routine vaccination was started in 1999. Over the last 4 decades, the average age of hepatitis A infected individuals has increased. The reported hepatitis A incidence has declined by 90% to as low as 1.2 cases per 100,000 population. The frequency of acute hepatitis is higher in those U.S. Mexico has a high prevalence of individuals with the anti-HAV antibody indicating a previous infection. In recent years there has been a decline in the incidence of a new infection. Improved sanitation has resulted in a shift in the age group that acquires hepatitis A. Blood transfusion is a very rare cause of hepatitis A. Most cases of transmission are from person to person and limited to close contacts. The incidence of acute HAV infection has decreased by 92% from 12 cases per 100,000 in 1995 to 1 case per 100,000 in 2007. With the implementation of vaccination, the incidence of HAV in the United States has significantly decreased. The incidence of HAV in a given population correlates with socioeconomic properties such as income, the density of housing, sanitation, and water quality. High-risk groups in low endemicity countries have been identified as injection-drug users, men who have sex with men, people traveling to endemic areas, and isolated communities such as nursing homes and even day-care centers. Infection rates are low in developed countries such as the United States, Canada, and Western Europe. Exposure in these developing countries usually occurs in childhood. Endemic rates are high in developing countries with low socioeconomic conditions and poor sanitation and hygiene practices. The WHO estimates that approximately 1.5 million people are infected with HAV each year. HAV is one of the most common causes of acute hepatitis infection worldwide. Globally, the rates of HAV have decreased due to improvements in public healthcare policies, sanitation, and education, but infection rates of other hepatitis viruses appear to be increasing. Vaccination against HAV is recommended for children 12 months or older and adults with the risk of exposure including travelers to endemic countries, men who have sex with men, illicit drug users, potential occupational exposure, and/or chronic liver disease. Alternate clinical patterns include cholestatic, prolonged, and relapsing disease. Typical symptoms of acute infection include nausea, vomiting, abdominal pain, fatigue, malaise, poor appetite, and fever management is with supportive care. Acute hepatitis usually presents as a self-limited illness development of fulminant hepatitis is rare. HAV does not cause chronic liver disease unlike hepatitis B or C. ![]() However, high-risk groups include injection-drug users, men who have sex with men, people traveling to endemic areas, and isolated communities. According to the World Health Organization (WHO), infection rates in developed countries are low. HAV is most commonly transmitted through the oral-fecal route via exposure to contaminated food, water, or close physical contact with an infectious person. The hepatitis A virus (HAV) is a common infectious etiology of acute hepatitis worldwide. ![]()
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