Typhoid

Overview

•Caused by Salmonella typhi (Gram-negative, facultative intracellular bacillus); paratyphoid caused by Salmonella paratyphi - both collectively termed enteric fever

•Transmission: faecal-oral route (contaminated water/food); incubation 1-3 weeks (range 6-30 days)

•Classic setting: returning traveller from South Asia (India, Pakistan, Bangladesh) or sub-Saharan Africa

Presentation

Gradual onset with a characteristic three-week progression - knowing which features appear in which week is key to answering clinical vignettes.

Week	Key features
Week 1	Systemic illness - rising fever, headache, malaise; constipation; relative bradycardia (Faget's sign)
Week 2	Persistent high fever; rose spots (faint salmon-pink blanching macules, periumbilical); non-bloody yellow-green ('pea-soup') diarrhoea
Week 3	Week 2 features + complications: hepatosplenomegaly, GI haemorrhage/perforation, sepsis

🎯

Relative bradycardia (Faget's sign): pulse is disproportionately low for the degree of fever - a normal or low pulse in a febrile traveller should immediately raise suspicion for typhoid.

💡

Rose spots are present in only ~30% of cases but are highly specific - they represent bacterial emboli in dermal capillaries during bacteraemia and contain viable S. typhi.

Investigations

🏆 Gold standard

•blood culture - positive in ~60-80% in week 1; multiple sets increase yield

🥇 First-line

•stool culture - positive from week 2 onwards as biliary shedding increases

•FBC: characteristically normal or low WCC (leucopenia) - key distinguishing feature; most bacterial infections cause leucocytosis

•CRP and LFTs: CRP raised; transaminases mildly elevated (hepatic involvement)

•Bone marrow culture: highest sensitivity (~90%) - reserved for diagnostically difficult cases or when blood cultures are negative after antibiotics

⚠️

Leucopenia in a febrile returning traveller with prolonged illness is a red flag for typhoid - do not be falsely reassured by a 'normal' FBC. This reflects intracellular infection of the bone marrow by S. typhi.

Management

•First-line (uncomplicated, South Asia): azithromycin oral 500 mg once daily for 7 days - preferred given high fluoroquinolone resistance rates

•First-line (severe/complicated or unable to take oral): ceftriaxone IV 2 g once daily - third-generation cephalosporin active against most strains

•**Ciprofloxacin** - historically first-line but widespread fluoroquinolone resistance in South Asia limits use; may be appropriate outside high-resistance areas guided by sensitivities

•XDR typhoid (Pakistan): specialist infectious diseases input; carbapenems may be required

•Supportive care: fluid resuscitation, antipyretics, nutritional support; ITU and surgical input for perforation/haemorrhage/severe sepsis

📌

Typhoid is a notifiable disease in the UK - inform the local Health Protection Team immediately on suspecting or confirming a case.

Complications

•Intestinal perforation - most feared; 1-3% of cases; S. typhi ulcerates Peyer's patches in terminal ileum; presents with acute abdomen and peritonitis; requires emergency surgery

•Intestinal haemorrhage - erosion into mesenteric vessels; bloody stools with ongoing fever

•Sepsis/multi-organ failure - hepatic failure, renal failure, DIC in 10-15% of severe untreated cases

•Chronic carrier state - up to 5% carry >1 year; gallbladder reservoir; associated with gallbladder carcinoma risk

•Case fatality <1% with treatment vs up to 20% untreated