Chlamydia infections in Montana have increased 17 percent since 2005, with people ages 15-24 accounting for 75 percent of cases, according to data released Monday by the Montana Department of Public Health and Human Services.

There were 2,757 cases of the sexually transmitted disease reported in 2007, compared to 2,368 in 2005.

The next most most common sexually transmitted disease in 2007 was gonorrhea, with 122 cases. There were eight cases of syphilis reported.

According to Laurie Kops from the sexually transmitted diseases section of DPHHS, education is a big key in fighting the spread of the disease. She said people should talk with their kids about sex in health-related terms.

"We really need parents and schools to come to their children's aid," she said. "The more you talk about it the easier it is to talk about preventing it so kids really realize they are at risk."

Chlamydia is easily treated with antibiotics, but if untreated, it can cause infertility in women from scar tissue in the fallopian tubes. It can also cause infertility in men, but that is less common.

Also, 40 percent of women with untreated chlamydia get pelvic inflammatory disease, according to the Centers for Disease Control.

Kops said changing social mores is a big reason for chlamydia's rise.

"Sex is everywhere," she said. "It's not as taboo as it used to be. If you talk to any kid, you'll see that."

Kops also said some young people engage in oral sex, thinking it will preserve their virginity, but chlamydia and other STDs also are spread by oral sex.

The best way to prevent chlamydia is abstaining from sex or using condoms. Also, limiting the number of sex partners will reduce the odds of contracting the disease.

Montana's chlamydia increase mirrors a national trend. More than 1 million cases of chlamydia were reported nationally in 2006, according to the Centers for Disease Control. That was the highest total since 1984.

Most people who get chlamydia have no symptoms, and it is believed that the actual number of infections is three times the number reported.

People who are sexually active should be tested for chlamydia, especially those under 25, Kops said.

For those who do have symptoms, the most common are painful urination and a discharge of clear fluid.

The larger number of infections for chlamydia compared to other STDs is largely attributable to the fact that the bacteria that causes chlamydia is far more common, Kops said.

April is National STD Awareness Month.