Three years after Virginia public health officials thought syphilis was almost eradicated, the disease has surged, with the number of cases doubling.

In 2006, the number of cases rose 31 percent to 352, The Washington Post reported. In the first quarter of 2007, the number of cases was 39 percent above those reported in the same period a year earlier.

The District of Columbia and other areas around the country are seeing similar jumps in numbers. Health officials say most new infections are in gay or bisexual men.

Investigators are unsure of the reason for the disease's resurgence. One theory is that men who know they are HIV-positive have stopped using condoms, leaving them open to other infections.

Syphilis' initial symptoms are minor and the disease can usually be treated with antibiotics at that stage. However, in its later phases, syphilis can cause severe physical damage, including to the brain.

Copyright 2007 by United Press International