🌴 Chapter 109: Tropical Infections in PICU

Scrub typhus · Leptospirosis · Enteric fever · Japanese encephalitis · Cholera · Pandemic influenza A (H1N1) · Ebola · Doxycycline · Azithromycin · Ceftriaxone · Oseltamivir

🔍 Core Concepts: Tropical Infections in PICU

🕷️ Scrub typhus
Orientia tsutsugamushi, vector: chigger. Eschar, rash, lymphadenopathy, ARDS, MODS. Diagnosis: ELISA IgM. Treatment: doxycycline or azithromycin.
💧 Leptospirosis
Weil's disease: jaundice, renal failure, hemorrhage. Diagnosis: MAT, IgM ELISA. Treatment: penicillin G, ceftriaxone, doxycycline. Avoid in pregnancy (doxy).
🌡️ Enteric fever (typhoid)
Salmonella typhi/paratyphi. Stepwise fever, relative bradycardia, rose spots. Treatment: ceftriaxone, azithromycin. Dexamethasone for severe encephalopathy/DIC.
🧠 Japanese encephalitis
Bilateral thalamic involvement on MRI, parkinsonism, seizures. Supportive care. No specific antiviral. Vaccine preventable.
💦 Cholera
Rice-water diarrhea, rapid dehydration. Treatment: rehydration (ORS/IV Ringer's lactate), doxycycline/azithromycin, zinc.
🤧 H1N1 influenza
Oseltamivir (2 mg/kg/dose BID x5d). Droplet + contact precautions. N95 for aerosol-generating procedures.
⚠️ Ebola
High mortality, supportive care, isolation (PPE, N95). No approved therapy. Fruit bat reservoir.

🩺 Stepwise Approach: Undifferentiated Tropical Fever in PICU

1
History & exam clues
Travel, season (rainy), animal/water exposure (leptospirosis), eschar (scrub typhus), rash, bradycardia (typhoid), rice-water stool (cholera).
2
Diagnostic workup
Blood smear (malaria), rapid tests (scrub typhus IgM, leptospira IgM, typhidot), blood culture (typhoid), PCR (H1N1). Consider CT/MRI for JE (bilateral thalamic).
3
Empiric antibiotics while awaiting tests
Scrub typhus/leptospirosis: doxycycline (or azithromycin if <8 years). Enteric fever: ceftriaxone ± azithromycin. Cholera: rehydration + doxycycline/azithromycin.
4
Supportive & organ-specific care
Shock: fluids, vasopressors. ARDS: lung protective ventilation. Renal failure: dialysis. Encephalitis: ICP management, seizure control (JE).
5
Infection control
H1N1: droplet/airborne precautions. Ebola: strict PPE, isolation. Cholera: contact + enteric precautions.