Epstein-Barr virus-encoded small RNAs (ribonucleic acids) (EBER) are small pieces of genetic material made by human cells that have been infected with Epstein-Barr virus (EBV). Pathologists use a special test called in situ hybridization to look for EBER inside cells. Cells that produce EBER are labeled positive or reactive, while those that do not produce EBER are labeled negative or non-reactive. Some types of cancers can be caused by EBV and pathologists often perform the test to look for EBER inside cancer cells. Cancers associated with EBV include nasopharyngeal carcinoma, Burkitt lymphoma, and Hodgkin’s lymphoma.