Hepatitis A virus (HAV) is a positivestrand RNA virus transmitted feco-orally through person-to-person contact. Poor sanitation, overcrowding, or food and water contamination often cause outbreaks. In children, hepatitis infection is usually without symptoms, but adults can have jaundice (yellowing of skin or whites of eyes), abdominal pain, and hyperbilirubinemia. If a person has immunoglobulin M antibodies, a diagnosis can be made, and treatment is supportive. Vaccination is the mainstay of prevention and should be given before exposure whenever possible.

Hepatitis B virus (HBV) is a partly double-stranded DNA virus that causes acute and chronic liver infections. Hepatitis B vaccination is recommended for the following groups: medically stable infants weighing 2,000 g or more within 24 hours of birth; unvaccinated infants and children; and unvaccinated adults requesting protection from hepatitis B or are at increased risk of infection. Screening for hepatitis B is recommended in pregnant women at their first prenatal visit and adolescents and adults at high risk of chronic infection. Acute hepatitis B symptoms include jaundice or elevated serum alanine transaminase levels and test results showing hepatitis B surface antigen and hepatitis B core antigen. There is no evidence that antiviral treatment is effective acutely; however, chronic hepatitis B is defined as the persistence of hepatitis B surface antigen for more than six months. Hepatitis C virus (HCV) is an infection by a virus that attacks the liver and leads to inflammation. It is spread by coming into contact with contaminated blood, like sharing needles or from unsterile tattoo equipment. Chronic HCV infection is one of the leading causes of liverrelated death, and in many countries, it is the primary reason for having a liver transplant. The main aim of antiviral treatment is to eradicate the virus. Hepatitis C virus (HCV) infects more than 300 million people globally, with increasing incidence in developing countries. HCV infection frequently progresses to chronic liver disease, creating a heavy economic burden on resource-poor countries and lowering the patient’s quality of life. Until a few years ago, the only treatment strategy used a combination of pegylated interferon and ribavirin (PEG/RBV). However, in genotypes 1 and 4, the rates of viral response did not surpass 50%, reaching up to 80% in the rest. Hepatitis D is caused by the hepatitis D virus (HDV), a unique RNA pathogen that requires the hepatitis B surface antigen (HBsAg) to infect a person. Hepatitis D is transmitted by the parenteral route. Transmission requires contact with infectious blood. At-risk populations include intravenous drug abusers and people who have received multiple blood transfusions. Symptoms include abdominal pain, nausea, and fatigue. The main susceptible group is patients with chronic HBsAg infection who become superinfected with the virus. Approximately 5% of individuals infected with hepatitis B virus (HBV) are also infected with hepatitis D virus (HDV). Chronic HBV/HDV coinfection is associated with a negative outcome, with many patients developing liver cirrhosis, liver failure and eventually hepatocellular carcinoma within 5-10 years. Hepatitis E virus was first recognized as the cause of an epidemic of unexplained acute hepatitis in the early 1980s. Globally, it is one of the most frequent causes of acute viral hepatitis. The majority of HEV infections are asymptomatic and lead to the spontaneous clearance of the virus. Hepatitis E is mainly transmitted through drinking water contaminated with fecal matter. Symptoms include jaundice, lack of appetite, and nausea. In rare cases, it may progress to acute liver failure. Hepatitis E usually resolves on its own within four to six weeks. Treatment focuses on supportive care, rehydration, and rest.