Makindo Medical Notes

**Note:** Patients may exhibit relative bradycardia (heart rate lower than expected for fever) and a surprisingly low white cell count (WCC) despite significant systemic symptoms.

About

• Typhoid Fever: Caused by *Salmonella typhi*
• Paratyphoid Fever: Caused by *Salmonella paratyphi* (types A, B, and C)

Aetiology

• Children aged 1-5 years are particularly vulnerable.
• Transmission is primarily through faeco-oral routes, typically via contaminated food or water.
• The gallbladder may act as a reservoir in carriers, even post-treatment.
• Bacteria localize to lymphatic tissue in the small intestine, such as Peyer’s patches, which can swell, ulcerate, and in severe cases, lead to intestinal bleeding.

Characteristics

• Gram-negative, motile rods, facultative anaerobe.
• Ferments glucose, oxidase-negative, catalase-positive.
• Reduces nitrates to nitrites.
• Non-lactose fermenting, producing pale colonies on MacConkey agar.
• Resistant to bile salts (sodium deoxycholate).

Clinical Presentation

• Incubation Period: 10-14 days for Typhoid, shorter for Paratyphoid.
• Progression by Weeks:
  • Week 1 (Symptomatic Phase): Dry cough, malaise, headache, and a stepwise rise in fever up to 39°C. Patients may experience constipation or diarrhoea. Relative bradycardia may be noted.
  • Week 2 (Signs Develop): Rose spots (bacterial emboli) on the abdomen and thorax, epistaxis, shock, splenomegaly, hepatomegaly, and lymphadenopathy. Bradycardia persists.
  • Week 3 (Complications): Potential complications include toxaemia, bowel haemorrhage, intestinal perforation, cholecystitis, osteomyelitis (especially in sickle cell patients), myocarditis, nephritis, meningitis, and pneumonia.
  • Week 4 (Recovery): Symptoms start to resolve in those untreated, though some may experience prolonged illness or become chronic carriers.
• Long-Term Complications: Chronic carriers, often harboring *S. typhi* in the gallbladder, can excrete bacteria intermittently, posing a risk of transmission.
• Paratyphoid Fever: Similar but generally milder, with a shorter course and more abrupt onset. Rash may be more prominent, and intestinal complications less frequent.

Children with sickle cell disease have an increased risk of bone and joint infections due to *Salmonella* species.

Investigations

• Full Blood Count (FBC): Often shows low WCC and elevated AST/ALT levels.
• Blood Cultures: Positive for *S. typhi* or *S. paratyphi* in the first 1-2 weeks.
• Stool Cultures: Positive from the second week onwards.
• Urine Cultures: May show presence of *Salmonella* during the infection course.
• Widal Test: Historically used but unreliable and generally outdated.

Management

• **Untreated Duration:** Typhoid fever typically lasts for at least four weeks without treatment.
• Infection Control: Isolate in a side room with strict hygiene protocols.
• Antibiotic Therapy:
  • First-Line: Ciprofloxacin 500-750 mg BD (up to 500 mg QDS) PO for 10 days.
  • Alternative: Azithromycin 500 mg daily for 10-14 days if quinolone resistance is suspected.
• Chronic Carrier State: Ciprofloxacin 500 mg BD PO for 4 weeks. Some chronic carriers may require cholecystectomy if antibiotics alone are ineffective.
• Public Health Notification: Report cases to the local Health Protection Agency (HPA) or relevant authority as typhoid is a notifiable disease.
• Food Handling Restriction: Infected patients should avoid food handling duties until three consecutive negative stool cultures confirm clearance of the bacteria.

Prevention

• Vaccination for Travellers: IM capsular polysaccharide vaccine is recommended for travelers to endemic areas.