What is Lymphogranuloma venereum?
Lymphogranuloma venereum, commonly known as LGV, is a specific and invasive form of sexually transmitted infection. It is caused by distinct strains of the bacterium Chlamydia trachomatis, specifically the serovars L1, L2, and L3. These particular strains behave more aggressively than the ones that cause the more common type of chlamydial infection.
The defining characteristic of LGV is its ability to penetrate beyond the initial site of infection on the skin or mucous membranes and invade the body’s lymphatic system. The disease typically unfolds in three sequential clinical phases. The initial (primary) stage involves a small, temporary genital or rectal lesion. The infection then progresses to a secondary stage, marked by inflammation and swelling of regional lymph nodes (buboes), before potentially advancing to a late (tertiary) stage characterized by chronic tissue destruction and scarring.
Causes:- Infection by Specific Bacterial Strains: The sole cause of LGV is infection with the L1, L2, or L3 serovars of the bacterium Chlamydia trachomatis. These particular strains are biologically equipped to be more invasive than the common chlamydial strains, allowing them to cause a more complex, systemic disease.
- Transmission Through Direct Contact: The bacterium is passed from one person to another during sexual contact. Transmission happens when the mucous membranes of the genitals, anus, or mouth, or a small break in the skin, touch an infectious sore or secretions from an individual with LGV.
- Initial Site Inoculation: For an infection to begin, the bacteria must breach the body's surface. This occurs at the point of sexual contact, where the bacteria are introduced into the tissue, leading to the formation of an initial, often unnoticed, lesion.
- Migration to Lymphatic Tissue: A defining causal step of LGV is the bacterium's ability to travel from the entry point. The organisms actively move into the lymphatic system, where they multiply within the lymph nodes, triggering the intense inflammatory response that characterizes the second stage of the disease.
- Men Who Have Sex with Men (MSM): In Europe, North America, and Australia, outbreaks of LGV have been overwhelmingly concentrated among men who have sex with men. The infection is particularly associated with this demographic.
- Individuals with HIV: People living with a Human Immunodeficiency Virus (HIV) infection are more susceptible to acquiring LGV. Furthermore, the genital or rectal ulcers caused by LGV can increase the risk of both transmitting and acquiring HIV.
- Persons with Multiple Sexual Partners: Engaging in sexual activity with multiple or anonymous partners increases the statistical probability of encountering an individual who is infected with LGV, thereby raising the risk of exposure.
- Geographic Location: Although now seen globally, LGV remains historically endemic and more common in tropical and subtropical regions. This includes parts of the Caribbean, Africa, Southeast Asia, and South America.
