According to the Centre for Disease Control and Prevention (CDC), last year there were more than one million cases of chlamydia reported in the United States.
The CDC says as many as three-quarters of women infected with chlamydia experience no symptoms and although chlamydia is easily cured with antibiotics if treated early, left untreated, the infection can lead to a plethora of medical problems in particular for women, such as pelvic inflammatory disease, ectopic pregnancy and infertility.
Every year the CDC issues an "STD Surveillance Report" which details trends in the detection of chlamydia, gonorrhoea and syphilis, which are all caused by sexually transmitted bacteria; last year a rise in gonorrhoea and syphilis was also noted.
Of the trio, in 2006 chlamydia was the most prevalent with 1,031,000 cases, up from 976,000 in 2005; before that it was gonorrhoea which held the national record, with 1,013,436 cases reported in 1978.
The CDC says this is the second year in a row an increase for all three of sexually transmitted bacterial infections has been seen.
Experts say women are diagnosed with chlamydia three times more often than men are, and this disparity can be attributed to the tendency of women to be tested more often.
The report does suggest that the overall rise in all three infections could be due to the greater prevalence, and accuracy, of STD tests but could also reflect an actual rise in morbidity rates.
There were 358,366 cases of gonorrhoea reported in the United States in 2006, up from 339,593 in 2005 and just over 330,000 the year prior.
According to Dr. Stuart Berman, who helps tracks STDs for the CDC there is a hidden epidemic of STDs.
The CDC says some common viral infections such as human papillomavirus, which causes cervical cancer and genital herpes, are not reported to the agency at all.
Not using condoms and having multiple sex partners can increase the risk of spreading sexually transmitted diseases, including syphilis and AIDS; STDs increase a person's vulnerability to the AIDS virus and they also make HIV-infected people more infectious.
Left untreated, gonorrhoea too can cause a variety of health problems including infertility.
The potentially deadly disease syphilis, which is now relatively rare in the United States, also saw a rise from 22,288 in 2005 to 37,000 cases reported in 2006.
Syphilis which is also easily curable in its early stages, can cause serious complications if untreated, including brain, cardiovascular and organ damage, and even death.
