False-colour transmission electron micrograph (TEM) of the Lassa fever virus, which belongs to the Arenaviridae group of viruses. The picture shows the virion (red) containing 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% of cases due to heart or kidney failure. Magnification: x135,600 at 6x4.5cm size.