within 1 week), IgM antibodies are found in the blood. In late infection and after recovery, IgG antibodies are present and remain in the body for up to years. Therefore, when a patient is positive for IgG antibody but negative for IgM antibody, he is considered immune from the virus via either prior infection and recovery or prior vaccination.In the case of hepatitis B, blood tests exist for multiple virus antigens (which are different components of the virion particle) and antibodies. The combination of antigen and antibody positivity can provide information about the stage of infection (acute or chronic), the degree of viral replication, and the infectivity of the virus. Alcoholic versus non-alcoholic
The most apparent distinguishing factor between alcoholic steatohepatitis (ASH) and nonalcoholic steatohepatitis (NASH) is a history of excessive alcohol use. Thus, in patients who have no or negligible alcohol use, the diagnosis is unlikely to be alcoholic hepatitis. In those who drink alcohol, the diagnosis may just as likely be alcoholic or nonalcoholic hepatitis especially if there is concurrent obesity, diabetes, and metabolic syndrome. In this case, alcoholic and nonalcoholic hepatitis can be distinguished by the pattern of liver enzyme abnormalities; specifically, in alcoholic steatohepatitis AST>ALT with ratio of AST:ALT>2:1 while in nonalcoholic steatohepatitis ALT>AST with ratio of ALT:AST>1.5:1.Liver biopsies show identical findings in patients with ASH and NASH, specifically, the presence of polymorphonuclear infiltration, hepatocyte necrosis and apoptosis in the form of ballooning degeneration, Mallory bodies, and fibrosis around veins and sinuses.
There is some evidence of hepatitis E infection of animals, serving as a reservoir for human infection. Alcoholic hepatitis
Alcoholic hepatitis (AH) in its severe form has a one-month mortality as high as 50%. Most people who develop AH are men but women are at higher risk of developing AH and its complications likely secondary to high body fat and differences in alcohol metabolism. Other contributing factors include younger age <60, binge pattern drinking, poor nutritional status, obesity and hepatitis C co-infection. It is estimated that as much as 20% of people with AH are also infected with hepatitis C.  In this population, the presence of hepatitis C virus leads to more severe disease with faster progression to cirrhosis, hepatocellular carcinoma and increased mortality. Obesity increases the likelihood of progression to cirrhosis in cases of alcoholic hepatitis. It is estimated that 70% of people who have AH will progress to cirrhosis. Non-alcoholic steatohepatitis
Non-alcoholic steatohepatitis (NASH) is projected to become the top reason for liver transplantation in the United States by 2020, supplanting chronic liver disease due to hepatitis C.  About 20–45% of the U.S. population have NAFLD and 6% have NASH. The estimated prevalence of NASH in the world is 3–5%. Of NASH patients who develop cirrhosis, about 2% per year will likely progress to hepatocellular carcinoma. Worldwide, the estimated prevalence of hepatocellular carcinoma related to NAFLD is 15–30%. NASH is thought to be the primary cause of cirrhosis in approximately 25% of patients in the United States, representing 1–2% of the general population.