Faculty of Allied Medical Sciences Clinical Immunology & Serology Practice (MLIS 201). Typhoid fever. Prof. Dr. Ezzat M Hassan Prof. of Immunology Med Res Inst, Alex Univ E-mail: email@example.com. Teaching Objectives. To define Typhoid Fever
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Faculty of Allied Medical Sciences
Clinical Immunology & Serology Practice
Prof. Dr. Ezzat M Hassan
Prof. of Immunology
Med Res Inst, Alex Univ
Countries endemic for typhoid (U.S. CDC 2006)
Alex LaPointe, Wikimedia Commons
1. Caused by the bacterium Salmonella Typhi .
2.Ingestion of contaminated food or water.
3. Contact with an acute case of typhoid fever.
4. Contact with a chronic asymptomatic carrier.
How does the bacteria cause disease ?
Ingestion of contaminated food or water
Carried by white blood cells into the liver, spleen, and bone marrow
Multiply and reenter the bloodstream (Clinical illness)
Bacteria invade the gallbladder, biliary system, and the lymphatic tissue of the bowel and multiply in high numbers
Then pass into the intestinal tract (can be identified for diagnosis in cultures from the stool)
Typhoid ulcers can cause perforation and hemorrhage
become "carriers" of typhoid.
Aches and pains
Diagnosis of typhoid fever is made by
Serodiagnosis of Typhoid :
1.Detection of Antibodies in serum:
1.Widal test (Tube or Slide), 2.Typhidot assay
3.Tubex system, 4. Dipstick assay.
2. Detection of Antigens in serum:
1. Tubex system 2. Countercurrent Immunoelectrophoresis (CIE).
3. Co-agglutination test. 4. ELISA
3. Detection of Antigens in urine:
1.Tubex system 2. CIE,
3. Latex agglutination 4. Co-agglutination
H( flagella ) antigens
O (somatic) antigens
Vi (Virulence) capsular polysaccharide antigens
Induce rapid & High Abtitres;
Saline 0.5 0. 5 0.5 0. 5 0. 5 0. 5 0. 5
1:10 Patient serum 0.5 0.5 0.5 0.5 0.5 0. 5 discard
Serum dilution 1:20 1:40 1:80 1:160 1:320 1:640 -
Bacteria suspension0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5
Reagent (ml)1 2 3 4 5 6 7
Final serum dil. 1:40 1:80 1:160 1:320 1:640 1:1280 -ve
Bacteria suspension: O H PA PB
Shake several times, put it in 370C water bath for 16-18 hours. Then let it stand at room temperature over night.
**Do not shake tubes before reading the results
1. Control tube (Tube No. 7): no agglutination (-)
2. Lowest titer tube: absolutely agglutination (++++)
3. Other tubes:
¾ agglutination(+++) ½ agglutination (++)
¼ agglutination (+) no agglutination (-)
Agglutination titer: the highest dilution of serum
which appears (++) bacteria agglutination.
which agglutinations occurs is noted, ex. if the
dilution is 1 in 160 then the titer is 160.
in normal individuals . Agglutination in dilution
1:160 is suggestive of Salmonella infection.
confirmatory of Enteric fever .
Interpretation of results
1 2 3 4 5 6 7
O ++++ ++ ++ + - - -
H ++++ +++ ++ ++ - - -
PA ++ + - - - - -
PB - - - - - - -
1:40 1:80 1:160 1:320 1:640 :1280
Prozone effect - Occasionally, it is observed that when the concentration of antibody is high (i.e. lower dilutions), there is no agglutination and then, as the sample is diluted, agglutination occurs.
Lack of agglutination in the prozone is due to antibody excess resulting in very small complexes that do not clump to form visible agglutination
Note that during Reinfections, IgM may be absent or present at a low level transiently
1 drop of undiluted patient’s serum sample for
the 2 antigens is placed on the circled card.
1 drop of each of 2 salmonella antigens are added separately
rotated gently for 1 min.
Appearance of agglutination gives qualitative results.
(semiquantitative test is repeated with dilutions of serum)
80µl, 40µl, 20µl, 10µl, 5µl, of patient’s serum each for 2 salmonella antigens are placed on the circled card.
one drop of specific antigen is added to each series of serum.
Agglutination of each of these is noted.
Two main typhoid fever prevention strategies:
2. Avoid risky food and drinks
trimethoprim-sulfamethoxazole, Amoxicillin and ciprofloxacin etc used to treat typhoid fever.
Symptoms & Prevention of typhoid fever
ميرنا ابراهيم – نادية محمد سعد – نيهال كمال – هايدى احمد – هدى عبد الله