DefinitionChlamydia is a disease caused by the bacteria Chlamydia trachomatis. It is most commonly sexually transmitted.Causes, incidence, and risk factorsChlamydia infection is the most common sexually transmitted disease in the United States. Sexually active individuals and individuals with multiple partners are at highest risk.SymptomsAs many as 1 in 4 men with chlamydia have no symptoms. In men, chlamydia may produce symptoms similar to gonorrhea. Symptoms may include:Burning sensation during urinationDischarge from the penis or rectumTesticular tenderness or painRectal discharge or painOnly about 30% of women with chlamydia have symptoms. Symptoms that may occur in women include:Burning sensation during urinationPainful sexual intercourseRectal pain or dischargeSymptoms of PID, salpin