County of Los Angeles Public Health (May 5, 2025) Hepatitis A is a contagious liver infection caused by the hepatitis A virus (HAV). It is one of the most common forms of hepatitis worldwide. The infection can range from a mild illness lasting a few weeks to a severe illness lasting several months, and in rare cases, it can be fatal.  Viral Hepatitis | ACDC | LACDPH (lacounty.gov)