Typhoid/enteric fever

Question 1

Typhoid - organisms

Answer 1

Salmonella enterica serotype typhi
Salmonella enterica serotype paratyphi A, B + C
-Gram negative bacilli/rods

Express:
-LPS antigen 9 + 12 [somatic]
-Hd [flagellar]
-Polysaccharide capsular antigen Vi

Question 2

Typhoid - epidemiology

Answer 2

Highest prevalence in SE Asia
-500-700 per 100,000 per year
Highest incidence in young children

Question 3

Typhoid - presentation

Answer 3

IP 5-21 days [depends on amount of exposure]

Symptoms: fever, abdominal pain, constipation > diarrhea, headache, cough, myalgia, neuropsychiatric manifestations

Signs: abdominal tenderness [60%], HSmegaly [40%], rose spots [rare - small septic emboli], relative bradycardia

Question 4

Typhoid - complications

Answer 4

‘3rd week’ - more advance infection
Intestinal perforation - infection of Peyer’s patch
Bleeding
Sepsis
Mortality - currently 1-3% [pre-antibiotics - 15%]

Question 5

Typhoid - treatment

Answer 5

Azithromycin PO - 6 days

Ceftriaxone 10-14 days

Additional: dexamethasone only in severe cases

Question 6

Typhoid - diagnosis

Answer 6

Trial of treatment
Bloods:
-Leucopenia - neutrophils normal or low
-Moderately raised ALT - rarely >400
Blood culture [80%]
Bone marrow [90%]
Stool, urine
Widal’s test - false positive in vaccinated, previous infection, similar infections, faulty equipment

Question 7

Typhoid - prevention

Answer 7

Foodhandling, handwashing, water treatment - WASH

Healthy carrier - long term carriage 1-4% [gallbladder - increased risk of cancer]

Question 8

Typhoid - vaccines

Answer 8

Vi capsular polysaccharide
-1 dose infection
-70% protection lasts 2-3 years
-Age >2 years

Ty21a [oral live attenuated]
-4 doses, 60-90% effective, lasts 5-7 years
-Age >2 years

Vi-rEPA or Vi-TT [Typbar-TCV]
-Single dose
-90% protection
->6month age