More than 1 million cases of chlamydia were reported in the United States last year – the most ever reported for a sexually transmitted disease, the Centers for Disease Control and Prevention recently reported.

The annual report on chlamydia, gonorrhea and syphilis found that chlamydia is the most common disease.

Nearly 1,031,000 cases of chlamydia were reported last year, up from 976,000 the year before, breaking the single-year record for reported cases of any STD – 1,013,436 cases of gonorrhea, set in 1978.

Dr. David Lawrance, medical director at McKinley Health Center, said there are generally three factors at hand when measured disease rates increase.

“First, the rate may actually be increasing. Second, the disease may be better recognized and better reported, and third, treatment can fail,” Lawrance said. “The first two are probably both in play with chlamydia.”

Lawrance said he thinks the rate actually does appear to be increasing, but a highly effective method of prevention is a consistent use of condoms.

Health officials believe most cases of chlamydia in the United States go undiagnosed or unreported, and as many as 2.8 million new cases may actually be occurring each year, most significantly affecting young women.

In 2006, the chlamydia rate for women was three times higher than it was for men. Women ages 15 to 19 had the highest rate: 2,862.7 cases compared to 515.8 cases per 100,000 for women overall.

“I think even a lot of college students don’t have nearly enough respect for chlamydia and what an infection can do to a woman,” Lawrance said.

According to a CDC fact sheet, chlamydia is known as a “silent” disease because about 75 percent of women who are infected have no symptoms, and it can ultimately lead to infertility if untreated.

As the numbers vary by gender, they also differ by race.

According to the report, in 2006 the chlamydia rate among blacks was more than eight times higher than among whites, and the rate among Hispanics was three times higher than among whites.

Lawrance said the variance among different ethnic groups is most closely related to access to medical care, as income similarly varies.

Second to chlamydia in highest number of an STD reported – gonorrhea – in 2006, 358,366 cases of gonorrhea were reported in the United States.

Gonorrhea rates are increasing again after hitting a record low in 2004.

That year, the nation’s gonorrhea rate fell to 112.4 cases per 100,000 people, the lowest level since the government started tracking cases in 1941.

“One of the major challenges in preventing and treating gonorrhea is the growing number of gonorrhea cases that are resistant to antibiotics,” said John Douglas, director for the CDC’s division of STD prevention.

Researchers found the third STD, syphilis, a potentially deadly disease that first appears as genital sores, had an increasing number of cases as well.

Although syphilis rates in the United States remain at a low level, about 9,800 cases of the most contagious forms of syphilis were reported in 2006, up about 1,000 cases from the previous year.

Lawrance said he thinks that because of all the attention campuses and students give to STDs, some may think that college students had the most reported cases, but the rates among college students are actually much lower than for their non-college peers.

“We do a lot of STD screening. It is recommended annually for any woman under the age of 26 who is sexually active. It is recommended for anyone with symptoms, for men who have sex with men and for anyone with a new partner,” Lawrance said. “We treat it whenever we find it.”