Chlamydia is the most common sexually transmitted infection (STI) in North America, affecting both men and women, although women report the disease more often than men.
The infection is named after the bacterium that causes it, Chlamydia trachomatis. Most women and many men who are infected with the bacteria have no symptoms and therefore don't know they have chlamydia
Chlamydia is easily treated, but it can sometimes lead to serious complications if it isn't caught early enough. It is estimated that up to 40% of untreated women will develop pelvic inflammatory disease (PID), which can be very painful. The risk of abnormal pregnancies or infertility also increases with an untreated chlamydia infection.
Chlamydia is spread during sexual contact and is highly infectious. It can be transmitted through vaginal, anal, or oral sex.
Newborn babies can get infected if their mothers have chlamydia. Nearly two-thirds of infants born vaginally (i.e., not by caesarean) to infected mothers will contract chlamydia during delivery. In newborns, chlamydia infections appear as eye problems or respiratory problems rather than the typical genital infections seen in adults.
People with chlamydia don't always have symptoms. About 75% of women and about 50% of men won't show signs of infection. If symptoms start, they will show up within 1 to 3 weeks after exposure.
In men, chlamydia usually starts in the urethra. Symptoms often come and go, or might only be noticed during the first urination of the day. These include:
Chlamydia can cause a number of complications in both men and women. Men may:
In women, chlamydia usually begins on the cervix. While symptoms are rare in women, they can include:
Women can also develop a number of serious complications from a chlamydia infection. If left untreated, it can cause:
In both women and men, chlamydia can infect the rectum. This causes:
If the eyes are infected by chlamydia (conjunctivitis), symptoms are:
In infants with chlamydia, eye infections occur in about 30% to 50% of babies born to infected mothers, and the infection usually occurs within 2 weeks of delivery. If the infection isn't treated in time, it can lead to scarring of the cornea and permanent damage to vision. About 5% to 20% of babies born to infected mothers will get pneumonia, usually within 2 to 12 weeks after delivery. The chlamydial pneumonia can cause anything from mild symptoms to breathing problems that include a repetitive cough.