Hawai'i continues to have one of the highest rates of chlamydia in the nation, with 5,659 new cases of the sexually transmitted disease reported in 2007.

The state ranks ninth in chlamydia infection rates, while its rates for gonorrhea and syphilis are among the lowest in the United States, according to a report released last week by the Centers for Disease Control and Prevention.

Widely available screening to detect chlamydia is one reason Hawai'i's numbers are relatively high, but risky sexual behavior by young people is another, said Peter Whiticar, chief of the state Department of Health's STD/HIV Prevention Branch.

The CDC estimates that almost half of the 19 million new sexually transmitted infections that occur nationwide each year are among 15- to 24-year-olds.

The 2007 Youth Risk Behavior Survey, conducted by the Health Department, indicated that a quarter of Hawai'i high school students were sexually active and less than half used condoms during their last sexual encounter.

"The survey shows Hawai'i has one of the lowest rates of condom use of any state in the country. Increased risky behavior and very low condom use with a large pool of chlamydia leads to increasing numbers," Whiticar said.

"It's clear there are people having unprotected sex out there."

Whiticar noted that STDs can be spread by limited sexual contact such as oral sex, and that some young people "may be into denial that it's sexual activity because they don't have to worry about getting pregnant."

RISK HIGHER FOR YOUNG

Sexually active teenage girls and young women are at high risk for chlamydia because their cervix is not fully matured and is probably more susceptible to infection, the CDC said.

"The chlamydia rate remains very high, particularly in women under 25 years of age. We really recommend that sexually active women under the age of 25 be screened as frequently as possible," Whiticar said.

Chlamydia is the most frequently reported bacterial sexually transmitted disease in the U.S. Although easily diagnosed and treated, it often has no symptoms and goes undetected.

If left untreated, up to 40 percent of chlamydia infections in women can result in pelvic inflammatory disease, a condition that causes as many as 50,000 women to become infertile each year, the CDC said. Untreated chlamydia also can cause chronic pelvic pain and potentially fatal ectopic pregnancy.

Complications among men are rare.

TROUBLING TREND

In Hawai'i, chlamydia cases have increased in nine of the past 10 years, with a 117 percent rise in cases from 1998 to 2007.

The state's infection rate stood at 440 cases per 100,000 people in 2007, higher than the national rate of 370 per 100,000, according to the annual CDC report, Sexually Transmitted Disease Surveillance, 2007.

Case numbers for 2008 are not available, but in the first half of the year, there were 2,969 new reports of chlamydia in Hawai'i, Whiticar said.

The increased availability of urine testing for chlamydia means more men are being screened for the infection. The CDC said the national chlamydia rate in men increased by 43 percent from 2003 through 2007, compared with a 17 percent increase in women over the same period.

Of the 5,659 new cases reported in Hawai'i in 2007, 4,228 were women and 1,431 were men.

Because chlamydia is so prevalent, "many young women may be infected by having just one sexual partner. You don't have to have lots of partners to be infected," Whiticar said.

"The good news is that there are good tests and good treatment for chlamydia. The bad news is that unless partners also are treated, there's a good chance of reinfection."

Nationally, there were more than 1.1 million new chlamydia cases reported in 2007, up from about 1 million in 2006, making it the largest number of cases ever reported to CDC for any one condition.

Gonorrhea, the second most commonly reported infectious disease, had more than 350,000 new cases reported in 2007.

The CDC report shows 659 new gonorrhea cases reported in Hawai'i in 2007, down from a peak of 1,263 cases in 2003. The state's gonorrhea infection rate is 51 cases per 100,000 people, which ranks 37th nationally.

Whiticar said gonorrhea tends to be found in an older population than chlamydia and is more common among men.

Hawai'i syphilis cases dropped from 61 in 2003 to only nine cases in 2007. The state's infection rate was 0.7 cases per 100,000 people, which ranks 44th nationally.

Although the numbers remain relatively low, syphilis remains a persistent public health threat, officials said.

"We haven't been able to eliminate syphilis. Although it's not a huge scourge, it's something we need to be vigilant about because it can move into populations that don't have regular access to healthcare where it is more difficult to detect," Whiticar said.

In fact, the Health Department is investigating a handful of recent cases of syphilis traced to the Chinatown area, he said.

Chlamydia, gonorrhea and syphilis can be transmitted during vaginal, anal or oral sexual contact, and also can be passed from an infected mother to her baby during childbirth. All three can be treated successfully with antibiotics.

Whiticar said the surest way to avoid transmission of STDs is to abstain from sexual contact, or to be in a long-term mutually monogamous relationship with a partner who has been tested and is known to be uninfected. Condoms, when used consistently and correctly, can reduce the risk of transmission of STDs.

The CDC recommends yearly chlamydia testing of all sexually active women age 25 or younger, older women who have a new sex partner or multiple sex partners, and all pregnant women.