Typhoid Fever — Diagnosis & Treatment

Typhoid is transmitted via the faecal-oral route through contaminated water or food. Incubation period 7-14 days. The classic 'step-ladder' fever pattern (rising by 1°C daily over 4-5 days) is the exception, not the rule. Clinical features: fever (often high, continuous), headache, abdominal pain, constipation (more common than diarrhoea in adults), relative bradycardia (Faget's sign — pulse-temperature dissociation), coated tongue, hepatosplenomegaly, rose spots (blanchable erythematous macules on trunk — seen in 30% of light-skinned patients), dullness in right iliac fossa. Complications: intestinal perforation (3rd week, ileocaecal area), GI haemorrhage, encephalopathy, myocarditis, hepatitis, cholecystitis (carrier state).

Risk factors: contaminated water, street food, poor sanitation, household contact with carrier. Chronic carrier state occurs in 2-5% of cases (usually women > 50, gallstones present) — these individuals shed Salmonella in stool for years.

• Blood culture (gold standard): Sensitivity 60-80% in first week, falls thereafter. Collect 5-10 mL in BACTEC bottle before antibiotics. Most sensitive in first week of fever.
• Widal test: Tube agglutination test detecting antibodies against O (somatic) and H (flagellar) antigens. Single titre > 1:160 O or > 1:80 H is presumptive evidence. Four-fold rise in paired sera (acute and convalescent) is confirmatory. Limited specificity — past infection, vaccination, anamnestic response can give false positives.
• Stool culture: Positive from 2nd week onwards; useful for chronic carrier detection.
• Bone marrow culture: Highest sensitivity (90%) even after antibiotics started. Reserved for difficult cases.
• Typhidot (IgM): Rapid card test — detects IgM antibodies within 2-3 days. Limited sensitivity/specificity, not widely recommended.
• CBC: Leukopenia (WBC < 4000) with relative lymphocytosis, thrombocytopenia, mild transaminitis (AST > ALT).
• NAAT (PCR): High sensitivity, costly — used in research and outbreak settings.

Empiric choice depends on local resistance pattern. Indian recommendations:

• First-line (susceptible): Cefixime 20 mg/kg/day in 2 divided doses x 7-14 days OR Azithromycin 20 mg/kg OD x 5-7 days
• Multidrug-resistant (MDR — resistant to chloramphenicol, ampicillin, cotrimoxazole): Cefixime or Ceftriaxone IV 75-100 mg/kg/day x 7-14 days
• XDR typhoid (resistant to first-line + fluoroquinolones + third-gen cephalosporins): Azithromycin OR Meropenem IV (severe cases). Oral Azithromycin preferred if patient can take orally.
• Severe typhoid (with perforation, shock, encephalopathy): Ceftriaxone IV 75 mg/kg/day + Dexamethasone 3 mg/kg loading then 1 mg/kg 6-hourly x 8 doses. Steroids reduce mortality in severe typhoid with delirium/shock.

Fever clearance time: 4-7 days. Continue antibiotics for full course even if fever resolves earlier — prevents relapse. Defervescence followed by recrudescence suggests resistant organism or inadequate dose — switch antibiotic.

Chronic carrier treatment: Ciprofloxacin 750 mg BD x 4 weeks OR Ceftriaxone IV 2 g OD x 2 weeks. Cholecystectomy if gallstones present — cures carrier state in 85% of cases.

• Safe water and food: Boiled water, freshly cooked food, hand washing before food and after defecation
• Sanitation: Toilet use, safe sewage disposal, no open defecation
• Carrier detection and treatment: Food handlers screened, chronic carriers treated
• Typhoid Conjugate Vaccine (TCV): Typbar-TCV (Bharat Biotech) — for ages 6 months to 45 years, single IM dose. Long-lasting (5+ years). Introduced in India's routine immunisation in some states in 2024.
• Vi polysaccharide vaccine (older): For ages ≥ 2 years, single dose, protects for 2-3 years. Booster every 3 years.
• Ty21a oral vaccine: Live attenuated, for ages ≥ 6 years, 3-4 capsules on alternate days. Lower efficacy than TCV.

Typhoid management has been transformed by TCV vaccination and molecular diagnostics, but XDR strains remain a global threat. For UPSC CMS aspirants, Widal interpretation, XDR typhoid treatment, and TCV introduction are high-yield topics.