Hepatitis is an inflammation of the liver, most commonly caused by a viral infection. There are five main hepatitis viruses, referred to as types A, B, C, D and E. Hepatitis B and C lead to chronic disease, are the most common cause of liver cirrhosis and cancer. Hepatitis A and E are typically caused by ingestion of contaminated food or water. Hepatitis B, C and D usually occur as a result of parenteral contact with infected body fluids. Common modes of transmission for these viruses include receipt of contaminated blood or blood products, invasive medical procedures using contaminated equipment and for hepatitis B transmission from mother to baby at birth, from family member to child, and also by sexual contact.
Mongolia is one of the highly endemic countries for hepatitis virus infections, particularly hepatitis B and C. Hepatitis virus infections accounted for more than one third of the total reported communicable diseases in the country. The country introduced Hepatitis B vaccine into its National Immunization Programme, 1991. Since then, the incidence of acute hepatitis B has declined among vaccinated children.