Cases of sexually transmitted diseases are on the rise in California but Santa Barbara County numbers are still below the state average.

Syphilis, Chlamydia Infection and gonorrhea cases are the three STDs the state Department of Public Health is saying have jumped dramatically in Californians and local public health doctors have some possible reasons for the increase.

Syphilis cases rose by 18 percent in 2011, chlamydia rose 5 percent and gonorrhea increased by 1.5 percent.

For chlamydia and gonorrhea, the age group with the largest number of cases is 20 to 24 year olds, but what might be surprising is syphilis is most common in 45 year olds and older.

"One theory is that the tests for syphilis have gotten better so now if someone has a primary syphilis ulcer and we test for it, we're much more likely to diagnose it than we were say 50 years ago," said Dr. Charity Thoman, Santa Barbara County Department of Public Health officer.

But there isn't a specific reason for the increase in these three types of sexually transmitted diseases.

"One possible explanation is that the reporting system for the state of California changed about a year ago to a computer based reporting system which allows us to see numbers in real time. That's one possible explanation for the increase in cases that we're seeing. However there could be a real increase. It might not be artificial, this could be real," explained Dr. Thoman.

But if it is that people are becoming infected more than in recent years, it could be from risky behavior or people becoming complacent about practicing safe sex.

The STDs on the rise are treatable with antibiotics if they are caught early and before they lead to more serious health issues.

"The big problems with gonorrhea and chlamydia is that there are long term consequences of infection. In females it can actually cause infertility," she said.

Dr. Thoman encourages people who are sexually active to be tested if they think they might have an STD. She also suggests being tested during an annual physical exam.