Hepatitis A is a liver disease caused by the hepatitis A virus. In children, the most common form of hepatitis is hepatitis A (also called infectious hepatitis). This virus lives in the stools (feces or poop) of infected individuals. This is most commonly transmitted by the fecal-oral route via contaminated food or drinking water. Hepatitis A does not have a chronic stage and does not cause permanent liver damage.
Virus
The 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. Genome consists of a single +ve stranded RNA with 7478 nucleotides, which codes for 4 proteins; - VP1 VP2 VP3 VP4.
Pathogenesis
Following ingestion, HAV enters the bloodstream through the epithelium of the oropharynx or intestine. The blood carries the virus to its target, the liver, where 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 approximately 11 days prior to appearance of symptoms or anti-HAV IgM antibodies in the blood. The incubation period is 15-50 days, and mortality is less than 0.5%.
Transmission
The virus spreads by the fecal-oral route and infections often occur in conditions of poor sanitation and overcrowding. Hepatitis A can be transmitted by the parenteral route but very rarely by blood and blood products. Food-borne outbreaks are not uncommon and ingestion of shellfish cultivated in polluted water is associated with a high risk of infection. Approximately 40% of all acute viral hepatitis is caused by HAV. Infected individuals are infectious prior to onset of symptoms, roughly 10 days following infection. The virus is resistant to detergent, acid (pH 1), solvents (e.g., ether, chloroform), drying, and temperatures up to 60oC. It can survive for months in fresh and salt water. Common-source (e.g., water, restaurant) outbreaks are typical. Infection is common in children in developing countries, reaching 100% incidence, but following infection there is life-long immunity. HAV can be inactivated by: chlorine treatment (drinking water), formalin (0.35%, 37oC, 72 hours), peracetic acid (2%, 4 hours), beta-propiolactone (0.25%, 1 hour), and UV radiation (2 ?W/cm2/min).
Symptoms
Early symptoms of hepatitis A infection can be mistaken for influenza, but some sufferers, especially children, exhibit no symptoms at all. Symptoms typically appear 2 to 6 weeks, (the incubation period), after the initial infection.

Symptoms can return over the following 6-9 months which include:
Fatigue
Fever
Abdominal pain
Nausea
Diarrhea
Appetite loss
Depression
Jaundice, a yellowing of the skin or whites of the eyes
Sharp pains in the right-upper quadrant of the abdomen
Weight loss

Diagnosis
> Although the virus is excreted in the feces towards the end of the incubation period, specific diagnosis is made by the detection of Hepatitis A virus specific IgM antibodies in the blood.
> IgM antibody is only present in the blood following an acute hepatitis A infection.
> The presence of IgG antibody in the blood means that the acute stage of the illness is past and the person is immune to further infection.
Hepatitis A Treatment
> There are no specific medicines to cure infection with hepatitis A. Most people require no treatment except to relieve symptoms. Most people fight off the virus naturally, returning to full health within a couple of months.
> Most cases of hepatitis A resolve themselves spontaneously.
> Hepatitis A immunization is given in a series of injections.