A group of viruses, so-called because under the electron microscope they have a sand-sprinkled (Latin, arenosus) appearance. Among the diseases in humans for which they are responsible are Lassa fever in West Africa, Argentinian haemorrhagic fever (mortality rate 3-15 per cent), a similar disease in Bolivia (mortality rate 18 per cent), and lymphocytic choriomeningitis, in which deaths are uncommon.
Any of a group of RNA viruses that are a source of zoonotic infections throughout the world. Some species in the group (e.g., Guanarito, Junin, Machupo, and Sabia virus) cause hemorrhagic fevers. Others (e.g., lymphocytic choriomeningitis virus) cause aseptic meningitis.