All of the following are characteristic features of scrub typhus EXCEPT:

## Distinguishing Scrub Typhus Features ### Characteristic Clinical Presentation **Key Point:** The eschar (tache noire) is the hallmark lesion of scrub typhus, appearing at the bite site of infected chiggers. It is present in 50–80% of cases (not >90%), and when present, is highly suggestive of the diagnosis. **High-Yield:** The rash in scrub typhus typically appears on **days 4–6** of illness, NOT on day 1. The rash is maculopapular, involves the trunk and proximal extremities, and may spare the palms and soles. ### Organism & Transmission | Feature | Detail | | --- | --- | | **Causative agent** | *Orientia tsutsugamushi* (formerly *Rickettsia tsutsugamushi*) | | **Classification** | Obligate intracellular, gram-negative coccobacillus | | **Vector** | Larval trombiculid mites (chiggers) | | **Geographic range** | 'Tsutsugamushi triangle': Japan to Afghanistan to Australia | | **Seasonal pattern** | Autumn and winter in temperate zones; year-round in tropics | ### Clinical Timeline 1. **Incubation:** 6–21 days (median 10–12 days) 2. **Day 1–3:** Fever, headache, myalgia; eschar may be visible 3. **Day 4–6:** Maculopapular rash appears (trunk → extremities) 4. **Week 2–3:** Peak fever; hepatosplenomegaly, lymphadenopathy 5. **Week 3–4:** Defervescence with appropriate antibiotic therapy **Clinical Pearl:** The absence of an eschar does NOT exclude scrub typhus; up to 50% of patients may lack this sign. Diagnosis relies on clinical suspicion, serology (Weil-Felix test, ELISA), or PCR. **Warning:** Rash timing is a common exam trap—students often confuse scrub typhus (day 4–6) with measles (day 3–4) or other exanthems. The eschar is the distinguishing feature when present. ### Why Option 4 Is Incorrect The rash in scrub typhus appears on **days 4–6**, not day 1. Early fever and eschar may be present, but the rash is a later sign. This is a classic NEET PG distractor because students may conflate fever onset with rash onset.