Viruses such as Concept, Wazzu, NPad and CAP have spread internationally. Many macro viruses do nothing significant beyond global spreading, but some macro viruses overwrite data, modify the contents of documents and even send documents out of a company via e-mail. After local area networks and the internet became common, boot viruses were not so prevalent or threatening. Macro viruses cause most of the infections in the world today, and now they far outnumber boot viruses. Some viruses are created by virus writers, some are created by natural mutation.
All macro viruses have the potential to spread and cause computer-infections in the real world.
However, most of them are not really widespread. But a macro virus can become widespread very quickly - the CAP.A virus spread globally in less than two months and infected tens of thousands of machines. The F-PROT Professional antivirus toolkit from Data Fellows is automatically updated several times each day. And thanks to exact identification, new definitions added by Data Fellows antivirus experts can be distributed to users immediately, since there is no risk of false alarms. Other antivirus products rely on search strings, which can be found in clean macros as well.