Arenaviruses were first discovered in 1933, when LCMV caused can ouster of encephalitis in St. Louis. Rodents are hosts for the virus, and spread to humans through contact with urine, feces, nesting material or through bites and scratches. From there, the virus can be spread from person-to-person through direct contact with bodily fluids such as blood or saliva. Arenaviruses are dived into two groups based on geography and genetic diversity. New world viruses such as X,Y, Z are found in North and South America, while Old World viruses such as Lassa (LASV), Lujo and LCMV are found in Africa, Europe, and Asia.