Widal test is old reliable way of diagnosing the cause of typhoid fever. Typhoid fever is very common in developing countries where there is no proper sanitation and access to clean water is limited.
Widal test is old reliable way of diagnosing the cause of typhoid fever. Typhoid fever is very common in developing countries where there is no proper sanitation and access to clean water is limited. Widal test is easy, affordable and available in all diagnostic centers registered. There are various tests but widal is reliable for this food borne condition which can lead to serious chronic fever and impact other parts of the body.
What is the Widal Test?
Widal test is very common test used to detect the cause of typhoid fever. There are various conditions related to typhoid fever like fatigue, fever, night sweat, chills, vomiting etc. This test is best for diagnosis of typhoid fever because of its reliability, high accuracy and affordability. There are two types of antigen produced after the infection of 7-9 days and which may reach to peak in couple of weeks.
Why is the Widal Test Done?
The Widal test is used for:
- Diagnosing typhoid fever and paratyphoid fever.
- Detecting a current or recent infection caused by Salmonella typhi.
- This test is very effective in differentiating typhoid and other illnesses.
Widal Test Procedure
The Widal test can be done using two techniques:
1. Slide Agglutination Test (Rapid Test)
- A small amount of the patient’s serum is mixed with specific antigens on a glass slide.
- If clumping (agglutination) is observed, it indicates a positive result.
- This is a qualitative test and gives faster results but may be less accurate.
- The last dilution at which visible agglutination occurs is noted as the antibody titer.
Widal Test Normal Range
Normal Values:
- O antigen (TO): Less than 1:80
- H antigen (TH): Less than 1:160
Widal Test Positive Means?
The positive test of widal means that patient is infected with the bacteria and need care and treatment to come out of this position.
Interpretation of Widal Test Results:
|
Antibody |
Titer Level |
Interpretation |
|
TO (O) Antigen |
≥1:160 |
Suggests active infection |
|
TH (H) Antigen |
≥1:160 |
Suggests past or current infection |
|
AH (Paratyphi A) |
≥1:80 or 1:160 |
Suggests paratyphoid A infection |
|
BH (Paratyphi B) |
≥1:80 or 1:160 |
Suggests paratyphoid B infection |
Advantages of Widal Test
- Easy to perform
- Low cost
- Rapid results (especially with slide test)
Limitations:
- Lower sensitivity and specificity compared to newer methods
- May not distinguish between current and past infection
- The test cannot detect the infection in early days
Done with other clinical tests like:
- With blood culture
- Stool/urine culture
- Typhi Dot test (IgM/IgG rapid test)
When is the Widal Test Recommended?
- Loss of appetite
- Headache and malaise
- Constipation or diarrhea
- Rose spots on skin
- Enlarged spleen or liver
It is generally performed after 5–7 days of fever, when antibodies start appearing in the blood.
Sample Collection for Widal Test
- Blood sample is collected from patient
- Sample is packed and marked
- Sample is send for processing in laboratory
- This test does not require fasting, but patient can reveal medical history and medications taking.
Widal Test Report Time
- Slide Test: Results within 1–2 hours.
- Tube Test: Results may take 24–48 hours.
In hospitals with modern laboratory setups, reports may be available on the same day.
Widal Test Charges in India
The charges of widal depends on various factors like location of healthcare facility, whether private or government, accreditations etc.
There are different types of Widal test and the range of charges for this test is usually Rs. 200 to Rs. 400 for slide test and for tube test it may be Rs. 300 to Rs. 600.
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Conclusion
Widal test is very important and affordable test for the detecting of typhoid fever cause. The usual cause of typhoid is Salmonella Typhi and its infection can lead to various abnormalities. The infection in the blood not only infects the body parts and has some serious symptoms. Chronic condition of typhoid is also very lethal, if the condition is not treated in time, it can lead to chronic conditions which are lethal. Widal test is best and great way to detecting the infection without going for any expensive test.
Frequently Asked Questions (FAQ’s)
Can the Widal test detect typhoid in early stages?
No. It usually becomes positive only after 5–7 days of illness.
Is fasting needed before the Widal test?
No, fasting is not required.
How accurate is the Widal test?
It has limited accuracy and is best used along with clinical evaluation and other tests like blood culture.
What if my Widal test is positive but I feel fine?
There is still infection and need to be treated as suggested by doctor.
Are there always symptoms during typhoid infection?
In some cases, it takes time for symptoms to appear even having the infection.
