Hepatitis virus (HAV) is a Picornavirus. It is non-enveloped and contains a single-stranded RNA packaged in a protein shell. There is only one type of the virus. HAV causes Hepatitis A (formerly known as infectious hepatitis), an acute infectious disease of the liver. This disease is most commonly transmitted by the fecal-oral route via contaminated food or drinking water. HAV infects approximately 10 million people every year worldwide, esp. in developing countries. The incubation period is 15-50 days, and mortality is less than 0.5%. Hepatitis A infection causes no clinical signs and symptoms in over 90% of infected children. Hepatitis A does not have a chronic stage and does not cause permanent liver damage. Following infection, the immune system makes antibodies against the hepatitis A virus that confer immunity against future infection (Wiki: Hepatitis A).
4. Microbial Pathogenesis
The virus spreads by the fecal-oral route, and infections often occur in conditions of poor sanitation and overcrowding. HAV enters the bloodstream through the epithelium of the oropharynx or intestine. Once HAV comes to the liver through the blood, it lives and multiplies within hepatocytes and Kupffer cells (i.e., liver macrophages). There is no apparent virus-mediated cytotoxicity, and liver pathology is likely immune-mediated. Virions are secreted into the bile and released in stool. HAV is excreted in large quantities ~11 days prior to appearance of symptoms or anti-HAV IgM antibodies in the blood (Wiki: Hepatitis A).
