Slide Widal Tube widal

1. WIDAL TEST
ANKUR
VASHISHTHA

2. HISTORY
 It was developed by Farnand Widal in 1896.
 Widal test is one of the oldest and most widley used
serological test for diagnosis of enteric fever.
 Salmonella antibodies start appearing in the serum at the
end of first week of fever.
 A rising titer of antibodies is indicative of enteric fever.

3. Principle
 It is an agglutination test
where H and O antibodies
against S.typhi and S.
Paratyphi A and B are
detected.

4. ANTIGEN USED
 Four antigen are used.
1. O antigen of S.Typhi (TO)
2. H antigen of S.Typhi (TH)
3. H antigen of S. Paratyphi A (AH)
4. H antigen of S. Paratyphi B (BH)

5. METHODS OF WIDAL TEST
 Two types as follows:-
1. Slide widal test (Rapid, Screening & Qualitative)
2. Tube widal test (Quantitative)

6. Slide widal test
 Mix one drop of patient serum & one drop of Ag
(O,H,AH,BH) in respective circle on slide.
 Mix properly & rotate for 1 min.
 Examine for clump.
 Put –ve & +ve control also.

7. Result
 Positive:- Clumps
 Negative:- No clump.

8. Interpretation of slide widal
SERUM VOLUME
(In microlitres)
APPROXIMATE TUBE TEXT
TITRE
80µl 1:20
40µl 1:40
20µl 1:80
10µl 1:160
5µl 1:320

9. Tube widal test
 Following are 4 main steps:-
i. Master dilution
ii. Serial Dilution
iii. Final dilution
iv. Incubation

10. Master dilution
 Take one tube & prepare 1:10 dilution of serum called
master dilution.
 Add 1800 µl of normal saline + 200 µl of patient serum.

11. Serial Dilution
 Take 16 test tube & arrange in 4 rows.
 Add 250 µl Normal saline in each test tube.
 Add 250 µl master diluted serum in 1st vertical row only.
 Do the serial dilution by transferring the 250 µl serum from 1st to
2nd vertical row 2nd to 3rd , 3rd to 4th & from 4th it will discard.
 So, dilution in 1st, 2nd, 3rd, & 4th vertical row is 1:20, 1:40, 1:80,
1:160 respectively.

12. Final dilution
 Add 250 µl O, H, AH & BH Ag 1st, 2nd, 3rd, & 4th
horizontal row respectively.
 So, final dilution in 1st, 2nd, 3rd, & 4th vertical row is 1:40,
1:80, 1:160 and 1:320 respectively.
 Put positive & negative control also.

13. incubation
 Test tube are incubated in water bath at 37ºC
overnight.(16-18 Hr.)
 Some authors recommend initial incubation at 50-55ºC
for 2 Hr.

14. RESULT
 O Agglutination:- Disc like clumps at bottom of tube.
 H Agglutination:- spherical, granular, cotton woolly
clumps at the bottom of test tube.
 Positive;- Indicating enteric fever.
 Negative:- No enteric fever.

15. Tube widal test

17. S.N
O.
Titre
(O/H/AH/BH)
INTERPRETATION
1 <40 Negative
2 Any one 40 Kindly repeat the after one weak to see rise in titer
3 O-80
H/AH/BH-40<40
Could be Early Typhoid/Paratyphoid Fever
Kindly repeat the after one weak to see rise in titer
4 O-40/<40
H/AH/BH-80
Could be past Typhoid/Paratyphoid Fever
5 O-80
Any one 160
Suggestive of Typhoid/Paratyphoid Fever
6 Any one 160 Suggestive of Typhoid/Paratyphoid Fever
7 O-160
Any one H-160
Significant for Typhoid/Paratyphoid Fever
8 Any one 320>320 Significant for Typhoid/Paratyphoid Fever
9 O-80/40/<40
Multiple H-80/160
Anamnestic Response with non Samonella organisms
(Malara, Dengue, Influenza etc.)

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