What Is Chlamydia? 

Chlamydia is a sexually transmitted disease (STD) caused by the bacteria Chlamydia trachomatis. When transmitted through  sexual contact, the bacteria can infect the urinary  and reproductive organs. 

The term  chlamydia typically refers to Chlamydia trachomatis,  the STD. But two other types of these bacteria also can lead to illness: Chlamydia pneumoniae, which can be spread through coughing  and sneezing, and Chlamydia psittaci, which birds can pass to humans. 

Chlamydia can be treated with antibiotics. But in many cases, it causes no symptoms, so people can be infected without even knowing it.  If chlamydial infections go untreated, they can lead to more serious health problems, such as infertility. So it's important to take the precautions to prevent chlamydia,  and if it's suspected, to seek treatment as soon as possible.