Machupo virus, Arenaviridae family, cause of Bolivian hemorrhagic fever (BHF). Like other New World Arenaviruses, infection by Machupo virus causes hemorragic fever syndromes; spread by rodents. Spherical and pleomorphic, with a diameter ranging from 50 to 300 nm in length (average of 120nm). Single-stranded and bi-segmented RNA genome. Contains ribosomes that give it a sandy appearance. Enclosed in a dense, lipid-containing envelope with 8-10 nm long club-shaped projections around outside.