False-colour transmission electron micrograph (TEM) of the Lassa fever virus, which belongs to the Arenaviridae group of viruses. The print shows the virion, which contains a mass of granules 20-30 nanometres in diameter, some of which are ribosomes derived from the host cell. Lassa fever is confined to central West Africa & is characterised by high fever, headaches, & severe muscular pain. Death occurs in over 50 percent of cases due to heart or kidney failure. Magnification: x54,250 at 35mm size. Gold tint. Original is BW print M050/090.