The amount of pornographic spam shot up by nearly 350 percent between June and July, according to the most recent spam statistics released by content security supplier Clearswift.

Pornography accounted for 17 percent of the spam tracked by Clearswift in July. Healthcare spam - mostly Viagra offers - also increased significantly, accounting for 41.4 percent of spam the company tallied.

The surge in pornographic porn follows the same pattern as last summer, according to Clearswift.

The company also released its first virus index, which it said showed that malicious activity is "getting more potent," with zombie and peer-to-peer networks facilitating the spread of viruses.