Chlamydia: Fast Facts

Reviewed By:
Timothy Yarboro, M.D.

• Chlamydia is the most frequently reported bacterial sexually transmitted disease (STD) in the United States, according to the Centers for Disease Control and Prevention (CDC), with gonorrhea and syphilis second and third in frequency. However, there are other STDs that physicians are not required to report to the CDC and local health departments that are also common, such as the human papillomavirus (HPV) and herpes.
  
  
• In 2006, more than 1 million chlamydia infections were reported to the CDC. But since many people are not aware of their infections and are not tested, the CDC estimates that the actual number of new infections each year is around 2.8 million. That means most chlamydia infections go undiagnosed.
  
  
• According to the CDC, the reported rate of chlamydia infection increased 5.6 percent from 2005 to 2006. The jump in the reported rate is probably the result of increased screening, use of more sensitive screening tests and improved reporting, as well as the continued high incidence of the disease.
  
  
• Although the disease affects both men and women, reported cases for women are much higher than those for men (three times higher in 2006 according to the CDC). This is probably because women are far more likely to be screened for chlamydia than men.
  
  
• Chlamydia is particularly common among teenagers and young adults, although it affects people in all age groups.
  
  
• In 2006, chlamydia rates in African American women were seven times higher than in white females. However, the disease is common among all races and ethnic groups.
  
  
• Chlamydia can spread through the cervix into the uterus or fallopian tubes and cause pelvic inflammatory disease (an infection of the uterus, fallopian tubes and other reproductive organs). This happens in up to 40 percent of women with untreated chlamydia according to the CDC – 20 percent of those women may become infertile.
  
  
• About 75 percent of women and 50 percent of men infected have no symptoms, according to the National Women's Health Resource Center (NWHRC).
  
  
• In 1999, the annual cost of treating chlamydia and its complications was more than $2 billion, according to the NWHRC.
  
  
• Men and women with chlamydia are more likely to become infected with human immunodeficiency virus  (HIV) if exposed to the virus.