Iminosugars and methods of treating infections caused by arenaviruses

Compound of formula: ** ** Formula or a pharmaceutically acceptable salt thereof, for use in an effective amount, in the treatment or prevention of a disease or condition caused by or associated with a virus belonging to the family Arenaviridae in a subject, wherein R is selected from substituted alkyl groups or or unsubstituted cycloalkyl groups, substituted or unsubstituted aryl groups substituted or unsubstituted oxaalkyl groups either substituted or unsubstituted; or wherein R is Formula ** ** R1 is an alkyl group substituted or unsubstituted; X1-5 are independently selected from H, NO2, N3 or NH2; Y is absent or is a C1 substituted or unsubstituted, other than carbonyl; and Z is selected from a bond or NH; provided that when Z is bond, Y is absent, provided that when Z is NH, Y is an alkyl group substituted or unsubstituted C1, other than carbonyl; and where W1-4 are independently selected from hydrogen, substituted alkyl groups or unsubstituted haloalkyl, substituted or unsubstituted groups, alkanoyl groups, substituted or unsubstituted aroyl groups, substituted or unsubstituted or haloalkanoyl groups substituted or unsubstituted.