The increasing number of spam emails represents a shift from relying on worm replication to using millions of bot-infested systems to spread viruses via email ("Botnets Fueling Unprecedented Attacks", Government Technology, 16 Mar 2007). Current events drive the content of the messages tricking interested users into thinking they're relevant.
Postini reported that, "...total spam has gone up 222 percent since November 2005 with 125 percent of this increase coming in the last 6 months. Major e-mail-borne virus attacks in January and February were aimed at creating more botnets for future attacks" (ibid). This increase in spam is not only increasing virus threats, it is also raising the cost to businesses of defending against the bot-driven onslaught of unwanted email. According to Ferris Research the global cost of spam will reach $100 billion in 2007 compared to $50 billion in 2005.
The following is a list of the top five viruses for February 2007 (ibid).