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FAMILY AND COMMUNITY MEDICINE
TYPHOID and PARATYPHOID FEVER
Dr. Alaa A.Salih -FICMS (FM) 27-12-2016
1. Identification
 A systemic bacterial disease with insidious onset of sustained fever,
marked headache, malaise, anorexia, relative bradycardia, splenomegaly,
nonproductive cough in the early stage of the illness, rose spots on the
trunk in 25% of white-skinned patients and constipation more often than
diarrhea in adults.
 The clinical picture varies from mild illness with low-grade fever to severe
clinical disease with abdominal discomfort and multiple complications.
 Factors such as strain virulence, quantity of inoculum ingested, duration
of illness before adequate treatment, age and previous exposure to
vaccination influence severity.
 Severe forms with altered mental status have been associated with high
case-fatality rates. The case-fatality rate of 10%–20%
 Paratyphoid fever caused by Salmonella enterica subsp. Enteric serovar
Paratyphi var. A and B (commonly S. Paratyphi A and B) presents a
similar clinical picture, but tends to be milder, and the case-fatality rate is
much lower.
 The causal organisms can be isolated from blood early in the
disease and from urine and feces after the first week.
 Blood culture is the diagnostic mainstay for typhoid fever, but
bone marrow culture provides the best bacteriological
confirmation even in patients who have already received
antimicrobials.
 Because of limited sensitivity and specificity, serological tests
based on agglutinating antibodies (Widal) are generally of little
diagnostic value.
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2. Infectious agents—
 The agent formerly known as S. typhi is called S. enterica subsp.
(commonly S. Typhi).
 For paratyphoid fever, mainly S. Paratyphi A and Paratyphi B.
3. Occurrence
 Worldwide; the annual estimated incidence of typhoid fever is about 17
million cases with approximately 600 000 deaths.
 Most of the burden of the disease occurs in the developing world.
 Currently most cases in the industrialized world are imported from
endemic areas.
 Strains resistant to chloramphenicol and other recommended
antimicrobials have become prevalent in several areas of the world.
 Paratyphoid fever occurs sporadically or in limited outbreaks.
 Of the 3 serotypes, paratyphoid B is most common, A less frequent and C
caused by S. Paratyphi C extremely rare.
4. Reservoir
 Humans for both typhoid and paratyphoid.
 Family contacts may be transient or permanent carriers.
 A carrier state may follow acute illness or mild or even subclinical
infections.
 In most parts of the world, short-term fecal carriers are more
common than urinary carriers.
 The chronic carrier state is most common (2%–5%) among persons
infected during middle age, especially women; carriers frequently have
biliary tract abnormalities including gallstones, with S. Typhi located in
the gallbladder.
 The chronic urinary carrier state may occur with schistosomal infections.
5. Mode of transmission
 Ingestion of food and water contaminated by feces and urine of patients
and carriers.
 Important vehicles in some countries include shellfish, raw fruit,
vegetables fertilized by night soil and eaten raw, contaminated milk/milk
products (usually through hands of carriers) and missed cases.
 Flies may infect foods in which the organism then multiplies to infective
doses (those are lower for typhoid than for paratyphoid bacteria).
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6. Incubation period
 Depends on inoculum size and on host factors; from 3 days to over 60
days—usual range 8–14 days.
 The incubation period for paratyphoid is 1–10 days.
7. Period of communicability
 As long as bacilli appear in excreta, usually from the first week throughout
convalescence; variable thereafter (commonly 1–2 weeks for paratyphoid).
 About 10% of untreated typhoid fever patients discharge bacilli for 3
months after onset of symptoms.
 2%–5% become permanent carriers.
 Fewer persons infected with paratyphoid organisms may become
permanent gallbladder carriers.
8. Susceptibility
 Susceptibility is general and is increased in individuals with gastric
achlorhydria and possibly in those who are HIV-positive.
 Relative specific immunity follows recovery from clinical disease,
inapparent infection and active immunization.
 In endemic areas, typhoid fever is most common in preschool children
and children 5–19.
9. Control measures:
 MEASURES DIRECTED TO RESERVOIR
a) Case detection and treatment
b) Isolation
c) Disinfection of stools and urine
d) Detection & treatment of carriers
 MEASURES AT ROUTES OF TRANSMISSION
a) Water sanitation
b) Food sanitation
c) Excreta disposal
d) Fly control
 MEASURES FOR SUSCEPTIBLES
a) Immunoprophylaxis
b) Health education
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TYPES OF VACCINES
1. Injectable Typhim -Vi
1. This single-dose injectable typhoid vaccine, from the bacterial capsule of
S. typhi strain of Ty21a.
2. This vaccine is recommended for use in children over 2 years of age.
3. Sub-cutaneous or intramuscular injection Efficacy : 64% -72%
2. Typhoral
1. This is a live-attenuated-bacteria vaccine manufactured from the Ty21a
strain of S. typhi.
2. The efficacy rate of the oral typhoid vaccine ranges from 50-80%
3. Not recommended for use in children younger than 6 years of age.
4. The course consists of one capsule orally, taken an hour before food with a
glass of water or milk (1st day,3rd day &5th day)
5. No antibiotic should be taken during this period
6. Immunity starts 2-3 weeks after administration and lasts for 3 years
7. A booster dose after 3 years
Indications for Vaccination
1. Travelers going to endemic areas who will be staying for a prolonged period
of time,
2. Persons with intimate exposure to a documented S. typhi carrier
3. Microbiology laboratory technologists who work frequently with S.typhi
4. Immigrants
5. Military personnel
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