Chlamydia trachomatis: epidemiology, pathogenesis, and clinical management

Chlamydia Trachomatis

Chlamydia is the most common and frequently occurring sexually transmitted disease in the United States. According to a recent CDC report there are more than 2.8 million persons infected every year. [CDC] The disease is caused by a bacterium known as Chlamydia trachomatis which is also found to exist as 15 different serotypes. The estimated annual treatment costs for Chlamydia is around $2 billion. The asymptotic nature of the disease presents a big problem in the early diagnosis and a substantial number of infected persons are unaware of their condition. Though totally curable, this 'silent disease' can cause trachoma, infertility, tubal pregnancy and other urinogenital disorders if left untreated. A brief overview of the disease, treatment options and preventive strategies would give a better insight of this medical condition.

Chlamydia trachomatis (Life Cycle)

Chlamydia trachomatis is a parasitic bacterium that cannot produce its own ATP and hence depends on host cells for its energy needs. It is an intracellular parasite which is mainly found to affect humans. This bacterium has a unique morphology that protects it from the immunological response of the human host. An important characteristic of this bacterium is that its life cycle is composed of two distinct stages known as the 'elementary bodies' and the 'reticulate bodies'. The elementary bodies are 0.3-0.4 µm sized spore like forms of the organism which possess a thick outer membrane with disulphide bonds. This protective outer wall provides the elementary bodies protection from the external conditions and also prevents the phagolysosome fusion in phagocytes and hence helps evade the typical phagocyte 'engulf and digest'mechanism. The cell wall has a lipopolysaccharide layer and there is no peptidoglycan. These elementary bodies attach themselves to the receptor cites on the surface of the host cells and induce endocytosis.

Once inside the host cell the elementary bodies evolve or change into a vegetative form known as the 'reticulate bodies'. Thus the reticulate form is actually the intracellular form of the bacterium. The reticulate form undergoes continuous replication by binary fission. These reticulate bodies do not have any distinct cell wall and are only identified as inclusions in the host cell. Once the fission is completed (approximately one division every 2 to 3 hours) the reticulate bodies reorganize into the elementary form and are thrown out of the cell by means of exocytosis. It is estimated that each cellular inclusion may contain 100-500 elementary bodies that are released out of the cell. Thus, by means of this unique two stage process Chlamydia trachomatis continues to multiply inside the host rapidly with minimal interference from the body's immune system. [Andrea DeMets]

Symptoms and Transmission

Chlamydia is a silent disease with very little early symptoms. Leukocyte esterase tests, DNA probes and ELISA tests can be used to confirm the infection. The disease is primarily transmitted through infected secretions. Being a sexually transmitted disease it is spread via intercourse and it mainly affects the mucosal membranes like cervix, urethra, rectum, conjunctiva and the throat. When the infected secretions are spread to the eyes by means of hands it may lead to trachoma. It is to be noted that trachoma is a serious problem and around 7 to 9 million people worldwide have acquired blindness due to Chlamydia. Reactive arthritis is also an observed condition in some patients. In women the main symptoms include increased or continuous vaginal discharge, pelvic pain, vaginal bleeding etc. Infected men may have white or yellowish discharge from the urethra accompanied by a burning sensation during urination. In acute cases lymphogranuloma venereum (swelling of the lymph nodes) may manifest leading to proctitis or other rectal discomforts. [University of South Carolina]

Prevention Strategies

Prevention instead of treatment should be the main focus of controlling an endemic disease such as Chlamydia. Maintaining good sexual hygiene and regular checkups with the physician are important. Monogamy is undoubtedly the best solution but in as much as possible preventive methods such as condoms should be used. It is also important for both the partners to undergo treatment in case infection is found in one of the two. Sexually active teenage girls and boys are the most at risk group for Chlamydia disease. Further it is found that 70% to 90% of infected women and 50% of men do not manifest any symptoms hence it is important to increase the awareness among young people. [Bisset Grady]. Regular screening programs organized at the school, college or community level would be helpful in early diagnosis of the disease and prevention of serious complications.

Conclusion

Chlamydia is an endemic sexually transmittable disease which can be completely cured if diagnosed early and treated appropriately. Creating awareness among the sexually active population, particularly the at-risk group (below 25), is important as the infection also makes people vulnerable for other dangerous conditions like gonorrhea and HIV. As with other sexually communicable diseases behavioral modifications constitute the best preventive strategy, however, a good sense of sexual hygiene and adopting safe sex methods would greatly reduce the risk of acquiring the infection.