A colony of C. trachomatis (colored green) is nestled inside a human cell. Image: V. Brinkmann, Max Planck Institute for Infection Biology
In the microscopic world of germs, organisms called Chlamydiae are dwarfed by their fellow bacteria. An E. coli bacterium can hang out with 100,000 of its closest friends on the head of a pin, but Chlamydiae are smaller still. Infectious particles are about one-tenth the length of an E. coli, rivaling the size of a large virus. And, just like a virus, Chlamydiae can still pack quite a punch, proving that sometimes, not-so-good things can come in small packages.
There are many types of Chlamydiae bacteria, but one species, Chlamydia trachomatis, is responsible for not one, but two sexually transmitted diseases (STDs) in humans: chlamydia and lymphogranuloma venereum (LGV). (Humans aren’t the only ones affected by sexually transmitted Chlamydiae. A different species, Chlamydia pecorum, is devastating wild koalas in Australia, which has got to be one of the biggest bummers ever.)
Chlamydia is a case study for the importance of safer sex and regular STD testing.
Chlamydia is one of the most common STDs in the United States — there were almost 1.5 million diagnoses in 2011 alone, but experts estimate that there were around another 1.5 million cases of chlamydia that went undiagnosed. How can this be? Chlamydia is often a “silent” infection, meaning that symptoms are rare, allowing people to harbor these bacteria without even knowing it. (When symptoms do occur, they might include swelling in the genital region; vaginal, cervical, or penile discharge; or painful urination.)
It might seem like a small mercy that this common infection is unlikely to torture us with harrowing symptoms — but, in actuality, those of us who have to deal with discharge or burning urination should try to appreciate the heads up: Left untreated, chlamydia can cause serious complications. When it spreads along the female reproductive tract, it can cause pelvic inflammatory disease, which can severely compromise fertility and cause chronic pain. Rarely, in a male reproductive tract, it can cause epididymitis, which can also spell bad news for future fertility. Continue reading