## Epidemiology of Enteric Fever in India **Key Point:** Salmonella typhi remains the predominant cause of enteric fever in India, accounting for approximately 60–80% of culture-confirmed cases, despite the introduction of typhoid conjugate vaccines. ### Relative Frequency of Causative Organisms | Organism | Frequency in India | Clinical Severity | Antimicrobial Resistance | | --- | --- | --- | --- | | *Salmonella typhi* | 60–80% | Moderate to severe | High (MDR, XDR emerging) | | *Salmonella paratyphi A* | 15–30% | Mild to moderate | Lower than S. typhi | | *Salmonella paratyphi B* | 5–10% | Mild | Rare | | *Shigella* species | <1% | Dysentery, not enteric fever | Variable | **High-Yield:** While S. paratyphi A has been increasing in prevalence over the past decade (especially in urban areas), S. typhi remains the most common cause overall. The ratio of S. typhi to S. paratyphi varies geographically within India. ### Clinical Pearls **Clinical Pearl:** S. typhi typically causes a prolonged, systemic illness with rose spots, splenomegaly, and a characteristic "rose-coloured" rash on the trunk in the second week. S. paratyphi A often presents with milder symptoms and shorter fever duration. **Warning:** Shigella causes bacillary dysentery (acute diarrhoea with blood and mucus), NOT enteric fever. Do not confuse the two entities. ### Diagnostic Confirmation Blood culture during the first week of illness has the highest yield (~80% for S. typhi). Bone marrow culture is more sensitive (~90%) but is reserved for suspected cases with negative blood cultures or prior antibiotic exposure. [cite:Harrison 21e Ch 159]
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