## Chlamydia trachomatis Serovars and Trachoma ### Serovar Classification **Key Point:** Serovars A, B, Ba, and C of Chlamydia trachomatis cause trachoma, a chronic keratoconjunctivitis endemic in developing countries, particularly in Africa, the Middle East, and parts of Asia. ### Serovar-Disease Correlation | Serovars | Disease | Clinical Features | |----------|---------|-------------------| | A, B, Ba, C | Trachoma (chronic) | Recurrent infection, scarring, trichiasis, entropion, blindness | | D–K | Inclusion conjunctivitis & urogenital infection | Acute follicular conjunctivitis, urethritis, cervicitis | | L1, L2, L3 | Lymphogranuloma venereum (LGV) | Systemic lymphadenopathy, proctocolitis | **High-Yield:** Serovars A–C are endemic in resource-limited settings and cause repeated infections over years, leading to progressive scarring and vision loss. Serovar Ba is a variant of B found in some endemic regions. ### Pathophysiology **Clinical Pearl:** Trachoma progresses through repeated infections in childhood. Each episode of inflammation causes conjunctival scarring, eventually leading to trichiasis (inturned eyelashes), entropion (inturned eyelid), and corneal opacity—the final pathway to blindness. ### WHO Elimination Strategy (SAFE) - **S**urgery for trichiasis and entropion - **A**ntibiotics (azithromycin) for active infection - **F**acial cleanliness to reduce transmission - **E**nvironmental improvement (water, sanitation) **Mnemonic:** **ABCL** — A, B, Ba, C cause trachoma; D–K cause inclusion conjunctivitis; L1–L3 cause LGV. 
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