Complete ROSH Gastrointestinal Practice Exam 2025

In the context of hepatitis infection, particularly when assessing for acute hepatitis, the presence of specific antibodies is crucial for determining the timing and nature of the infection. Anti-HBc-IgM is the antibody that indicates an acute hepatitis infection because it represents the first response of the immune system to the hepatitis B virus (HBV) after infection.

When a person is newly infected with HBV, the body starts producing IgM antibodies against the core antigen of the virus, which is labeled as Anti-HBc-IgM. This response occurs relatively early in the infection, making it a marker for acute hepatitis. In contrast, Anti-HBc-IgG arises later and indicates past or chronic infection rather than an acute one.

The other antibodies listed provide different information. Anti-HBe indicates a lower level of viral replication but does not specifically indicate an acute infection. Anti-HBs suggests recovery and immunity after infection or vaccination rather than active disease. Therefore, the presence of Anti-HBc-IgM is a key indicator of recent and acute hepatitis, making it the correct answer for identifying acute infection in the scenario presented.