Enteric fever (typhoid and paratyphoid) - Gastrointestinal infections

Enteric fever (typhoid and paratyphoid)

Definition

Typhoid (Salmonella typhi) and paratyphoid (Salmonella paratyphi A, B or C) produce a clinically identical disease.

Aetiology/pathophysiology

Humans are the only reservoir. Transmission is by the faeco–oral route or via contaminated food and water. The incubation period is 10–14 days. Organisms pass via the ileum and the lymphatic system to the systemic circulation causing a bacteraemia. Gut reinvasion leads to the clinical picture. Some secrete salmonella for over a year and measurement of Vi agglutinin is used to detect carrier states.

Clinical features

1.     The condition typically runs a course of around 1 month. Week 1 results from the bacteraemia. There is gradual onset of a viral like illness with headache and fever worsening over 3–4 days. There is initially constipation.

2.     Week 2 the patient appears toxic with dehydration, constant fever, abdominal pain and diarrhoea. Patients develop an erythematous maculopapular-blanching rash with splenomegaly.

3.     During week 3 complications include pneumonia, haemolytic anaemia, meningitis, peripheral neuropathy, acute cholecystitis, osteomyelitis, intestinal perforation and haemorrhage.

4.     Over the subsequent week there is a gradual return to normal health.

Investigations

Blood cultures are positive in 80% in week one and in 30% by week three. Stool cultures are more helpful in the second to fourth weeks.

Serological testing is by the Widal test measuring serum agglutinins against O and H antigens.

Management

Ciprofloxacin, chloramphenicol and amoxycillin have all been used.

Supportive management includes fluid and electrolyte balance and management of complications.

Carrier state eradication is by 4 weeks of ciprofloxacin and if unsuccessful cholecystectomy can be tried, as the gallbladder is often the site of infection.

A vaccine is available which gives some protection for up to 3 years.