In this 2007 image. Center for Disease Control (CDC) microbiologist. and Special Pathogens Branch staff member. Dr. Thomas Stevens. Jr. was peering out through an air-tight portal from inside the organizationˇs Biosafety Level 4 (BSL-4) laboratory decontamination shower. The shower leads into the changing room. were laboratorians could disrobe. safely removing their air-tight suits. The Special Pathogens Branch's (SPB) charter is the study of highly infectious viruses. many of them causing hemorrhagic manifestations in humans. Our daily work involves the investigation of viruses such as Ebola hemorrhagic fever. Marburg hemorrhagic fever. Lassa fever. Rift valley fever virus. Crimean-Congo hemorrhagic fever virus. arenaviruses and hantaviruses. and other recently identified and emerging viral diseases. Almost all of these viruses are classified as Biosafety Level 4 (BSL-4) pathogens and as such must be handled in special facilities designed to contain them safely. SPB operates one of the world's few BSL-4 laboratories. In addition. SPB provides technical and research/diagnostic materials to many international laboratories and collaborators. SBP staff members are trained to respond to global disease outbreaks and to provide assistance for disease detection and control measures.