After decades of searching, scientists have found a gene in Chlamydia trachomatis that produces a toxin responsible for an array of chronic illnesses. Discovery of the toxin also helps explain why only some strains of C trachomatis are harmful. Chlamydia infections are the most common sexually transmitted disease in the United States; the Centers for Disease Control and Prevention estimates that 3 million to 4 million new cases occur each year.
If left untreated, C trachomatis infection can cause pelvic inflammatory disease, conjuctivitis and trachoma (the most common preventable cause of blindness worldwide), infertility, tubal pregnancy, and epididymis. While these diseases differ by site, all have a common root: chronic inflammation. As far back as the 1940s, researchers suspected that a toxin caused the inflammation but had never found any helpful clues. The recent sequencing of the organism's entire genome filled that knowledge gap.
Vastag B. Chlamydia Toxin and Chronic Illness. JAMA. 2001;286(23):2934. doi:10.1001/jama.286.23.2934-JHA10013-3-1