Typhoid and Paratyphoid Fever (Enteric fevers)
Overview
Enteric fever is a systemic infection caused by Salmonella enterica serovars Typhi (typhoid) and Paratyphi (paratyphoid). Transmission is faeco‑oral, most commonly via contaminated food or water. Disease is endemic across the Indian subcontinent, parts of Africa, South/Central America and Southeast Asia.
Incubation is typically 7-21 days (paratyphoid may have a shorter incubation). Untreated typhoid historically carried high mortality (~15-30%); modern therapy greatly reduces this, but early recognition, appropriate sampling and empiric management are essential (UKHSA).
Pathogenesis and carriers
- The organism invades intestinal mucosa, replicates in Peyer’s patches and mesenteric lymph nodes, and disseminates within macrophages to produce systemic infection.
- A minority of patients (≈1-6%) become chronic carriers when organisms persist, often in the gallbladder, especially in the presence of biliary disease or gallstones.
- Chronic carriage is operationally defined as faecal shedding for more than 12 months and represents a significant public‑health risk, particularly for food handlers (UKHSA).
Clinical features - typical course
Always ask about recent travel to endemic areas in any febrile patient.
First week (prodrome)
- Gradual, stepwise high fever with malaise, headache, anorexia and abdominal discomfort.
- Constipation is common early; diarrhoea may be absent initially.