Typhoid fever, also known as Enteric fever

1. Typhoid Fever
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2. Introduction:
• Enteric fever, also known as typhoid fever.
• Is an acute illness associated with fever caused by the
Salmonella-typhi bacteria. Can also be caused by Salmonella
paratyphi, a related bacterium that usually causes a less severe
illness.
• Major cause of morbidity & mortality
• Food & water-borne disease.
• The bacteria is deposited in water/food by a human carrier & then
spread to other people.
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3. Etiology:
• Bacteria:
• Caused by bacteria: Salmonella typhi.
• Family: Enterobacteriacea
• Gram negative bacilli
• Best grows at 37 °C
• Transmission:
• Faecal-oral route (direct)
• Close contact with patients/carriers
• Contaminated water/food (indirect)
• Humans are the main reservoir for S. typhi.
• Salmonella has flagella.
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5. Is it contagious?
• Is typhoid contagious?
• Typhoid fever is HIGHLY contagious. An infected person can
pass the bacteria out of their body in their stools (faeces) or, less
commonly, in their urine.
• Contamination of water supply, in turn, taint the food supply. The
bacteria can survive for weeks in water or dried sewage.
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6. How do People get it?
• Work in or travel to area where typhoid is endemic (high risk
areas=refer to WHO map in pg.4)
• Work as a clinical microbiologist handling Salmonella typhi
bacteria.
• Have close contact with someone who is infected or has
recently been infected with typhoid fever.
• Drink water contaminated by sewage that contains S.typhi.
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7. How Long is a Person
Contagious?
• A person with typhoid fever is contagious anywhere from days
to years (assuming they become a chronic carrier); some
researchers suggest a few individuals may be contagious
indefinitely.
• About 3-5% of people become carriers of the bacteria after the
acute illness.
• Others suffer a very mild illness that goes unrecognized. These
people may become long-term carriers of the bacteria—even
though they have no symptoms—and be the source of new
outbreaks of typhoid fever for many years.
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8. Prognosis:
• With appropriate antibiotic therapy, most patients recover from the disease.
• However, 30% of people who do not receive therapy die. Annually, in the US,
there are about 300-400 cases & only one or two deaths each year.
• Most of those who got sick had failed to receive a vaccination prior to travel.
• Typhoid fever kill hundreds of thousands of people annually each year. Most
deaths occur in developing countries where the disease is common.
• With adequate treatment, less than 1% of victims should die.
• There is a concern that multi-antibiotic resistant strains of bacteria are becoming
more common worldwide.
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9. • Oral uptake of pathogen: A relatively large number of organisms (~105) is needed
to cause infection (high infective dose).
• Migration into Peyer patches of distal ileum: if the pathogen manages to reach the
distal ileum, it migrates via M-cells through the epithelium & into the Peyer
patches.
• Infection of macrophages (leads to non-specific symptoms manifested by
patient).
• Spread of macrophages to the bloodstream leading to septicemia and systemic
disease.
• Migration back into the intestine for re-circulation or excretion in feces.
• NB: *Organism invade macrophages & disseminates into organs of the
reticuloendothelial system(e.g. lymph nodes, liver, spleen, & bone marrow).
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Pathophysiology:

10. Clinical features:
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11. Clinical features:
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13. Symptoms:
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• Fig: Temperature curve in typhoid fever (stepladder fashion).
• NB: *Typhoid fever is a systemic disease and is not limited to the
gastrointestinal system.

14. Diagnosis:
• Blood culture
• Specific serological test
• Identify Salmonella antibodies / antigens
• Widal test & ELISA
• Urine & stool culture
• Marrow culture
• 90% sensitive unless until 5 days commencement of antibiotic
• Punch-biopsy samples of rose spots culture
• 63% sensitive
• Clot culture
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15. Laboratory tests:
• Anemia
• Leukopenia or leukocytosis
• Absolute eosinopenia.
• Relative lymphocytosis
• NB: *in adults, infection with Salmonella typically presents with
leukopenia, as opposed to most other bacterial infections. In
children, however, more commonly presents with leukocytosis.
• Abnormal liver function tests.
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16. Pathogen detection:
• Blood cultures: Bacteremia is detectable starting in week 1 of the
disease.
• Stool cultures:
• Cultures may be (+)ve from weeks 2-3, but are often negative
despite active infection.
• Bone marrow cultures:
• May be positive even after antibiotic treatment.
• Serology (Widal test):
• Pathogen detection from week 2 onwards possible.
• NB: *Blood culture is the most important diagnostic tool at disease onset, as
stool cultures are often (-)ve despite active infection.
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17. Serology
• WIDAL test – Tube agglutination test.
• Detects O and H antibodies
• Diagnosis of Typhoid & paratyphoid
• Testing for H agglutinins in Dryers tubes, a narrow tube floccules at the bottom.
• Testing for O agglutinins in Felix tubes, Chalky
• Incubated at 37°C overnight.
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18. Treatment:
• Activity – rest is helpful
• Medical care:
• Antibiotic
• Corticosteroids (for severe typhoid fevers)
• Antipyretics
• NB: *Antibiotics prolong the duration of fecal excretion of bacteria.
• Diet: fluid & electrolytes should be monitored
• Soft digestible diet is preferable in absence of abdominal distension
& ileus
• Surgical care – in cases of intestinal perforation.
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19. Antibiotic:
• Chloramphenicol (500mg qid)
• Ampicillin (750mg qid)
• Co-trimoxazole (2 tablets / iv bds)
• Fluoroquinolone (Drug of choice) – ciprofloxacin (500mg bds)
• 3rd generation cephalosporin – ceftriaxone (alternative); preferred for severe
infection.
• Azithromycin (500mg once daily) alternative when fluoroquinolone resistant
is present.
• Treatment should be continued for 2 weeks (14 days)
• Chronic carriers were formerly treated for 4 weeks with ciprofloxacin but
may require an alternative agent & duration
• Cholecystectomy may be necessary.
Resistance in many areas of the
world, esp. India & South East
Asia
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20. Complications:
• Bowel
• Perforation
• Hemorrhage
• Septicaemic Foci
• Bone & joint infection
• Meningitis
• Cholecystitis
• Toxic Phenomena
• Myocarditis
• Nephritis
• Chronic carriage:
• Persistent gallbladder carriage
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21. Prevention:
• Food & water security:
• Measures implemented to avoid exposure to organisms.
• Clean fruits & vegetables
• Get vaccinated
• WHO recommends vaccination to those travelling to high-
risk areas (East & Southeast Asia, South & Central
America, Africa).
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22. Sa Oji:
• Reference:
• Davidson’s Principle & Practice of Medicine 22nd Ed.
• Hutchison’s Clinical Methods 23rd Ed.
• Medscape
• MayoClinic
• Emedicine Health
• Malaysian Journal of Microbiology
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