A 28-year-old man from Delhi presents with a 10-day history of high-grade fever, headache, and abdominal pain. He reports constipation despite the fever. On examination, he is toxic-looking with a temperature of 39.8°C, relative bradycardia, and a faint rose-colored rash on the trunk. His abdomen is soft but tender in the right iliac fossa. Blood culture is pending. Complete blood count shows leukopenia with relative lymphocytosis. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Enteric Fever ### Key Clinical Features **Key Point:** The constellation of high-grade fever, headache, abdominal pain with constipation (not diarrhea), rose spots, relative bradycardia, and leukopenia with relative lymphocytosis is pathognomonic for enteric fever. ### Characteristic Presentation | Feature | Enteric Fever | Appendicitis | Dengue | | --- | --- | --- | --- | | **Fever pattern** | Sustained, stepladder rise | Acute onset | Biphasic (saddle-back) | | **Bowel habit** | Constipation (early) | Variable | Diarrhea | | **Relative bradycardia** | Present | Absent | Present | | **Rash** | Rose spots (trunk) | Absent | Maculopapular (whole body) | | **WBC count** | Leukopenia | Leukocytosis | Leukopenia | | **Blood culture** | Positive (week 1) | Sterile | Negative | ### Pathophysiology **High-Yield:** Salmonella typhi invades the Peyer's patches in the terminal ileum, causing hyperplasia and necrosis. This explains the right iliac fossa tenderness (ileitis, not appendicitis). The organism then spreads via mesenteric lymphatics and the bloodstream, causing bacteremia. ### Rose Spots (Rose Rash) - Small (2–3 mm), blanching, rose-colored macules - Appear on the trunk in crops - Represent septic emboli in dermal vessels - Present in ~5–10% of cases; absence does not exclude diagnosis ### Laboratory Findings **Key Point:** Blood culture in the first week has the highest yield (~80%). Widal test is positive from week 2 onwards but has poor specificity in endemic areas. 1. **Leukopenia with relative lymphocytosis** — characteristic of enteric fever 2. **Blood culture** — gold standard; positive in week 1 3. **Bone marrow culture** — most sensitive (90%), even after antibiotics 4. **Widal test** — O and H antibodies; limited value in endemic regions ### Fever Pattern (Stepladder) - Week 1: Sustained fever rising gradually - Week 2–3: Plateau at 39–40°C - Week 4: Defervescence (if untreated, may have complications) **Clinical Pearl:** Relative bradycardia (pulse-temperature dissociation) is a classic sign — fever of 39.8°C with a pulse <90 bpm is highly suggestive of enteric fever. ### Treatment Approach ```mermaid flowchart TD A[Suspected Enteric Fever]:::outcome --> B[Blood culture + Widal]:::action B --> C{Uncomplicated?}:::decision C -->|Yes| D[Ceftriaxone or Fluoroquinolone]:::action C -->|No| E[Complications present?]:::decision E -->|Perforation/Shock| F[Ceftriaxone + Supportive care]:::urgent E -->|Encephalopathy| G[Ceftriaxone + ICU]:::urgent D --> H[7–14 days IV therapy]:::action H --> I[Oral step-down if improving]:::action ``` [cite:Harrison 21e Ch 159]