Lujo is a bisegmented RNA virus—a member of the family Arenaviridae—and a known cause of viral hemorrhagic fever (VHF) in humans. Its name was suggested by the Special Pathogens Unit of the National Institute for Communicable Diseases of the National Health Laboratory Service (NICD-NHLS) by using the first two letters of the names of the cities involved in the 2008 outbreak of the disease, Lusaka (Zambia) and Johannesburg (Republic of South Africa). It is the second pathogenic Arenavirus to be described from the African continent—the first being Lassa virus—and since 2012 has been classed as a "Select Agent" under U.S. law. History Only 5 cases of this virus have ever been reported; all 5 were identified in September and October 2008, and 4 were fatal. Those infections that proved fatal caused death within 10–13 days of showing symptoms. All four patients in which infection proved fatal first showed signs of improvement and then went into respiratory distress, displayed neurological problems, and had circulatory issues that resulted in collapse. The discovery of this novel virus was described following a highly fatal nosocomial (hospital) outbreak of VHF in Johannesburg. The identification of this virus was the first new arenavirus discovered in over 40 years. The first case was a female travel agent who lived in the outskirts of Lusaka. She developed a fever which grew worse with time. She was evacuated to Johannesburg for medical treatment. Almost two weeks later, the paramedic that nursed the patient on the flight to South Africa also fell ill and was also brought to Johannesburg for medical treatment. At this time the connection between these two patients was recognized by the attending physician in the Johannesburg hospital. Together with the NICD-NHLS the clinical syndrome of VHF was recognized and specimens from the second patient were submitted for laboratory confirmation. In addition, a cleaner and a nurse that had contact with the first patient also fell ill. A second nurse was infected through contact with the paramedic. The outbreak had a high case fatality rate with 4 of 5 identified cases resulting in death. The Special Pathogens Unit of the NICD-NHLS together with colleagues from the Special Pathogens Unit of the U.S. Centers for Disease Control and Prevention (CDC) identified the etiological agent of the outbreak as an Old World arenavirus using molecular and serological tests. Sequencing and phylogenetic investigation of partial genome sequencing indicated that this