Enteric fever is caused by Salmonella enterica serovars Typhi and Paratyphi. It is transmitted through the fecal-oral route. The bacteria infects the lymphoid tissues of the small intestine and spreads to the liver, spleen and bone marrow. Common symptoms include sustained fever over 38°C, abdominal pain and hepatosplenomegaly. Blood cultures are the gold standard for diagnosis but other tests like the Widal test and Typhidot can also be used. Fluoroquinolones are usually the treatment of choice but azithromycin is an alternative. Treatment duration is typically 14 days to prevent relapse. Improving sanitation and hygiene as well as vaccination can

1. Enteric Fever
Dr. Sachin Nepali
MBBS

2. Enteric Fever
• Typhoid and paratyphoid
• Route of transmission: Faeco-oral route
• Causative agent:
– Salmonella enterica, serovar typhi
– Salmonella paratyphi A,B
• Gram –ve bacilli, non lactose fermenting

3. Pathogenesis
• On reaching small intestine the organism
penetrates the mucosa and infects lymphoid
follicles and subsequently the draining lymph
nodes and liver and spleen
• It multiplies in the reticuloendothelial system
• After 7-14 days spills into bloodstream and is
widely desseminated especially to liver, spleen,
bone marrow, gall bladder and peyers patches of
the terminal ileum

4. • These swells at first, thenulcerate and usually
heal.
• After clinical recovery, about 5% of patients
become chronic carriers; the bacilli may live in
the gallbladder for months or years and pass
intermittently in the stool and less commonly
in urine

5. Clinical features

6. Physical signs
• Coated tongue
• Tumid abdomen
• Hepatosplenomegaly

7. Clinical case definitions
• Confirmed enteric fever:
 Fever ≥ 38 ̊C for at least 3 days with a lab confirmed positive
culture typhi
• Probable enteric fever:
 Fever ≥ 38 ̊C for at least 3 days with a positive serodiagnosis or
antigen detection test but without typhi isolation
• Chronic carrier state:
 Excretion of typhi in stools/urine for longer than 1 year after
onset of acute enteric fever.

8. Complications

9. Relapse
• 5-15% of treated cases
• Higher with beta-lactams (Ceftriaxone,
cefixime) as compared to quinolones and
azithromycin

10. Investigtions
• CBC:
– Mild anaemia,
– low to normal TLC,
– Neutrophilia, Eosinopenia, thrombocytopenia
– [Anaemia & thrombocytopenia in advanced cases]
• CRP/ESR may be elevated
• LFT:
– ALP, Transaminases, bilirubin may be increased

11. • Urinalysis: look for proteinuria, pyuria, casts
• Blood culture
• Bone marrow culture
• Stool culture
• Rose spot culture
• Duodenal aspirate culture
• Nested PCR
• Serology

12. • USG: to detect hepatosplenomegaly
• X-Ray abdomen: if bowel perforation
suspected
• CT/MRI: For liver/bone abscesses

13. Gold Standard
• Blood culture is the gold standard for
diagnosis
• Bile broth media
• BACTEC media

14. • Bone marrow culture have higher yield as
compared to peripheral blood cultures as
Salmonella is a pathogen of RES and should be
done in later stages of illness.
• Done in who have been treated previously, have a
long history of illness and had a negative blood
culture
• Remains positive even after administration of
antibiotics
• Expensive and invasive
• Thus reserved for hospitalized and severely sick
patients

15. • Rose spot culture: Punch biopsy can be
cultured
• Duodenal aspirate culture: Not affected by
antibiotics and by duration of illness
• Nested PCR: 100% sensitivity, can detect even
one bacterium in a given sample within a few
hours, not affected by duration of illness and
antibiotics therapy

16. Specific tests
• Widal tests
• Typhidot
• IDL tubex test
• IgM dipstick test

17. Widal Test
• A/c to WHO it should be done within 1 weeks of
onset of fever
• Detects IgM & IgG antibodies to O and H antigens
• Anti O titres are both IgM & IgG that rise and
decline early(require 6-8 days to appear)
• Anti H are primarily IgG that rise and decline late
in course of diseases (require 10-12 days)

18. • Diagnosis is made if
 titres > 1:80 for anti-O
 titres > 1:160 for anti-H
• False positive in Malaria, Typhus, Bacteremia,
Cirrhosis
• Low sensitivity and specificity

19. Typhidot
• Positive in 1st week of illness
• Prefered over widal
• Sensitivity is 95%, Specificity is 75%
• Cost effectiveness
• Detects IgM & IgG antibodies to a specific 50
kD outer membrane protein antigen of S.
typhi

20. IDL Tubex Test
• Rapid test which takes 2 min to perform
• Can detect IgM O9 antibodies
• Not useful for diagnosis of current infections

21. Treatment
• Most can be managed at home on oral
antibiotics
• Children with persisting vomiting, poor oral
intake, severe diarrhoea or abdominal
distension require hospital admission

22. Antimicrobials
• Resistance to Chloramphenicol was first noted
soon after its first use in 1940
• Simultaneously resistant to all drugs that were
used as 1st line treatment
o Chloramphenicol
o Cotrimoxazole (Trimethoprim+Sulphamethoxazole)
o Ampicillin

23. • The fluoroquinolones remain the drugs of
choice (e.g. ciprofloxacin 500 mg 12-hourly).
• Extended-spectrum cephalosporins,
ceftriaxone and cefotaxime, are useful
alternatives but have a slightly increased
treatment failure rate.
• Azithromycin (500 mg once daily) has been
shown to be an alternative where
fluoroquinoline resistance is present but has
not been validated in severe disease.

24. Empirical therapy
• Uncomplicated:
– Cefixime 20mg/kg/day
– Azithromycin (10-20 mg/kg/day)
• Severe illness:
– Ceftriaxone, Cefotaxim (100mg/kg/day)
– Aztreonam, Chloramphenicol, Cotrim in higher
dose if h/o allergy to penicillins/cephalosporins

25. Duration of treatment
• Parenteral antibiotics continued until
defervescence has occured or oral intake has
improved or complications has resolved
• Then therapy can be switched to oral cefixime
or other oral drugs to complete total duration
of 14 days
Azithromycin, Amoxicillin, Cotrimoxazole, Cefopodoxime

26. • Treatment should be continued for 14 days.
Pyrexia may persist for up to 5 days after the start
of specific therapy.
• Even with effective chemotherapy there is still a
danger of complications, recrudescence of the
disease and the development of a carrier state.
• The chronic carrier should be treated for 4 weeks
with ciprofloxacin; cholecystectomy may be
necessary in some cases.

27. Therapy for relapse

28. Prevention
• Improved sanitation and living conditions
• Food hygiene
• Water hygiene
• Immunizations

29. Vaccination
• WHO recommends immunization for
– children aged over 2 years in endemic zones,
– individuals travelling to endemic zones,
– people who are in close contact with chronic
carriers,
– laboratory staffs who handles sample containing
S. typhi

30. Vaccines
• Vi polysaccharide:
– Single dose sc/im
– Protection begins from 7 days of infection and
maximum at 28 days
– Revaccination recommended every 3 years for
travellers
– Approved for persons aged over 2 years

31. Ty 21a oral vaccines
• Available in enteric coated capsule or liquid
• Should be taken in 3 doses with 2 days interval on an empty
stomach
• Gives protection from 10-14 days from 3rd dose
• Travellers should be vaccinated annually
• Antibiotics should be avoided for 7 days before and after
immunization
• Approved for use in children aged minimum 5 years

32. References
• Davidson Principle & Practice of Medicine
• OP Ghai, Essential Paediatrics 7th Edition
• Daily Rounds App
• Uptodate
• Medscape

33. THANK - YOU