Regarding the epidemiology and pathogenesis of rheumatic heart disease, all of the following statements are correct EXCEPT:

Explanation

## Epidemiology and Pathogenesis of Rheumatic Heart Disease ### Molecular Mimicry and Pathogenesis **Key Point:** Group A Streptococcus (GAS) M protein contains amino acid sequences homologous to human cardiac proteins, including myosin, tropomyosin, and keratin. This molecular mimicry triggers cross-reactive T-cell and B-cell responses, leading to autoimmune myocarditis and valvulitis. **High-Yield:** The latency period between GAS pharyngitis and ARF onset is typically **2–3 weeks**, allowing time for the immune response to develop. This distinguishes ARF from acute post-streptococcal glomerulonephritis (which occurs earlier, 1–2 weeks post-infection). ### Global Epidemiology **Clinical Pearl:** RHD remains the **leading cause of acquired valvular disease in developing and low-income countries**, particularly in South Asia, Africa, and the Pacific. In developed nations, degenerative valve disease (aortic stenosis from calcification, mitral regurgitation from degenerative changes) has replaced RHD as the leading cause. ### Risk Factors for Progression to Chronic RHD | Risk Factor | Impact | Notes | |-------------|--------|-------| | Female sex | Increased progression | Women progress more frequently to chronic RHD | | Younger age at first ARF | Increased progression | Earlier onset ARF → longer disease duration | | Recurrent ARF episodes | Marked increase | Each recurrence accelerates valve damage | | Socioeconomic factors | Increased progression | Poor access to penicillin prophylaxis | | Genetic predisposition | Increased risk | HLA-DR3, HLA-DQ2 associations | **Mnemonic:** **YFAR** — Young age, Female sex, Antecedent GAS, Recurrent episodes → progression to chronic RHD. ### Why the Correct Answer is Wrong The statement "Rheumatic heart disease is the leading cause of acquired valvular disease in developed nations" is **factually incorrect**. In developed countries, degenerative valve disease (primarily calcific aortic stenosis and mitral regurgitation from annular dilatation or leaflet degeneration) has become the leading cause of acquired valvular disease. RHD remains the leading cause in **developing and low-income countries**, not developed nations.