Health officials in San Diego have begun a media campaign to try to cut the rising rate of syphilis and other sexually-transmitted diseases.

San Diego County health officials recorded 312 new syphilis cases last year, up from 23 a decade ago. Chlamydia and gonorrhea cases in San Diego County also have increased, the San Diego Union-Tribune said Thursday.

Officials said they aren't sure why the rates are jumping so high.

"A possible explanation for the increase in gonorrhea, Chlamydia and syphilis cases could be that patients are not forthcoming about their sexual practices, making it difficult for their health providers to order appropriate tests," county health officials said in a statement.

The newspaper said 2005 statistics showed that about eight of every 10 syphilis cases in San Diego County were diagnosed in men who had sex with men.

Copyright 2008 by United Press International