Widal test is a test conducted in the laboratory for diagnosis of different type of species and sub species of salmonella that cause typhoid fever. There are different species and sub species of salmonella but it only few of them that cause typhoid fever. The following are the species and sub species of salmonella that cause typhoid fever in human being when ingested either through water or uncooked food or contaminated hand.
- Salmonella typhi O and H
- Salmonella paratyphi A
- Salmonella paratyphi B
- Salmonella paratyphi C
WIDAL TEST KIT REAGENT
Salmonella. typhi H 1 x 5ml
Salmonella. typhi O 1 x 5ml
Salmonella. paratyphi A-H 1 x 5ml
Salmonella. paratyphi A-O 1 x 5ml
Salmonella. paratyphi B-H 1 x 5ml
Salmonella. paratyphi B-O 1 x 5ml
Salmonella. paratyphi C-H 1 x 5ml
Salmonella. paratyphi C-O 1 x 5ml
The reagent are already made, and is commercially available in the store that sale laboratory reagent across the world.
DIFFERENT VARIETIS WIDAL TEST KIT
There are many companies that produce the reagent, and each of the reagent names is based on the company name that produced it. Bellow is some of the reagent provided with different company names;
- Cromatest widal kit reagent
- Omega widal kit reagent
- Acumen widal kit reagent
A whole blood is collected then serum is separated from the red cell packed, the separated serum is the sample used to carry out the serological test for typhoid fever.
WIDAL TEST PROCEDURE
- Collect a whole blood of 3-4ml volume
- Discard the blood into EDTA tube container
- In the absent of EDTA container, fluoride oxalate, or sodium heparin container can be used
- After discarding the blood in the container, cover it, invert the blood gentle to mix blood with the anticoagulant inside the container, then take the sample to bucket centrifuge, place it in the centrifuge used equal volume of blood or other fluid place it on the opposite of the blood sample in the centrifuge in other to balance the centrifuge when spinning to avoid unwanted vibration.
- Set the time on the centrifuge to 10 minute, and set the speed to 60rpm, then switch on the centrifuge.
- Allow the blood to spin until the centrifuge stop, allow the rotating motion to come to rest, then open the centrifuge and bring out the blood sample.
- In the absent of centrifuge the sample can be left on the working table for same time to sediment, after that the supernatant is separated from the red cell packed into a plain container.
- When the blood is clearly separated, a clear fluid of plasma is on the top, buffy coat on the center separating the red cell with the plasma. See picture bellow;
- On a clean grease free, dry white tire, dispense volume per volume of the widal kit reagent on the tire, see bellow table for clarity;
- After dispensing the reagent as shown in the table above, the add your sample as shown in the table below;
- Dispensing your reagent and serum as illustrated on the table above, mix the the reagent and the sample together using needle cap or any available mixing stick.
- After mixing your tire should resemble table below;
- After mixing as shown in the table above,
- Set your stop watch to 2 minute, then start rocking the tire and be checking constantly.
- Any agglutination seen when rocking, time of seen the agglutination should be noted.
- Stop rocking when the stop watch top.
REPORT YOUR RESULT AS FOLLOW
When agglutination seen within 0 – 30 second = 320
When agglutination seen within 30second – 1 minute = 240
When agglutination seen within 1minute – 1minute 30 second = 160
When agglutination seen within 1minute 30 second – 2minute = 80
When no agglutination seen, then record your result as follow;
1:20 1:20 1:20 etc. the format should be as shown in the table bellow
|S.P. TPHI A
|S.P. TPHI B
|S.P. TPHI C