acute hepatitis B virus infection (MONDO_0100370, a Monarch Disease Ontology entry) is a new infection by the hepatitis B virus, which can be transmitted by direct contact of infected blood with mucous membranes or open areas of the skin. Signs and symptoms may include loss of appetite, joint and muscle pain, low-grade fever and stomach pain. Two to six percent of adults progress to a chronic infection, while 90% of infants become chronically ill. A vaccine is available for those at risk. Also known as: acute hepatitis B.