Typhoid Fever

Bacterial food-borne infections

• Enterica
• Food poisoning
• Cholera
• Brucellosis
• Diarrheal diseases

Enteric Fevers (Enterica) Typhoid and Paratyphoid

Causative agent:

Salmonella Typhi Gram-negative facultative anaerobe Bacilli

Modes of transmission:

1. Ingestion of food (vegetables , fish & shellfish)or water contaminated by a. Handling : feces or urine of cases and carriers (Food Handlers). b. Vector: flies-cockraoches c. Dust: food exposed to contaminated dust

2. Direct hand to mouth infection.

Pathogenesis of typhoid

• The bacteria enter human digestive tract, penetrate intestinal mucosa and multiply in mesenteric lymph nodes, passes into blood ⇒ Bacteriaemia usually within the first week.

• The Bacteriaemia is temporary and the organism finally lodging in gall bladder.

• Organisms are shed into the intestine for some weeks.

Virulence factors

• Release of endotoxin and exotoxins.
• Salmonella strains may produce a thermolabile enterotoxin.

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Clinical Picture

Classic untreated cases

(1) Prodromal (invasion) stage: (1 week).

• Fever (stepladder rise) &gradual onset sustained fever  is usually higher in the evening.
• Pulse: bradycardia (slow relative to fever).
• Constitutional manifestation: malaise, headache, body aches, anorexia , sore throat and cough.
• Rash appears on 6th day.

(2) Advance stage: (2 weeks).

• Continued high fever.
• Worse physical and mental condition.
• Abdominal distension with diarrhea or constipation

Complications (advance stage):

1. Ulceration of payers’ patches
2. Intestinal hemorrhage:  2nd or 3rd week.
3. Intestinal perforation: 3rd week.
4. Cholecystitis,meningitis osteomyelitis thrombophlebitis              
5. Bronchitis and pneumonia.
6. Thrombophelibitis  (femoral vein).
7. Myocarditis.
8. Osteomyelitis, bone abscess, spondylitis and non-suppurative arthritis.
9. Others: nephritis, meningitis, mental dullness, slight deafness and parotitis.

(3) Decline stage or convalescence:  (4th week)

Uncomplicated cases gradually improves

• Temperature decreases .
• Abdominal manifestations disappear with satisfactory general condition.

(4) Relapse: in 10% of untreated cases

It occurs 1-2 weeks after return of temperature to normal.

Management of chronic carriers:Z

Ampicillin 1 gm every 6 hours for 1-3 months or quinolone is found to be effective.

If failed: surgical treatment of the pathological lesion (UB lesions in shistosomiasis, cholecystectomy).

-Should not be released from supervision and restriction until 3 consecutive –ve cultures 1month apart &at least 48 hrs after antimicrobial therapy has stopped

• Patients are probably cured if relapse does not occur within 2 years.

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Laboratory diagnosis:

1st week: blood cultures.

• Positive blood culture is conclusive
• (ve+ 75%)but  not exclusive

2nd & 3rd week:

• Widal test, stool & urine cultures.
• Bone marrow culture: the best bacteriologic confirmation (90-95%) even in patients received antibiotics.

Differential diagnosis:

• Brucellosis.
• T.B.
• Malaria.