Widal Test Procedure, Normal Ranges, Price, Test Results

wondering what the Widal test normal range is? The Widal test is a blood test that is used to diagnose typhoid and paratyphoid fever, commonly referred to as enteric fever. That’s why it is also called a typhoid test or enteric fever test. French physician Georges-Ferdinand-Isidor Widal discovered the test in 1896, and it eventually got named after him.

Both typhoid and paratyphoid are caused by Salmonella bacteria which can enter your system via contaminated food and water. One of the frequent sources of contamination is human feces. Therefore, a Widal test normal range ensures you are safe from all types of enteric fever. In this test, the blood collected from you reacts with the Salmonella antigens and goes on to form agglutination (clumping) or not.

The microorganisms commonly referred to as Salmonella bacteria include Salmonella Typhi, Para typhi A, Para typhi B, and Para typhi C, and the fever caused by them can be acute. That is why it is prudent to maintain a Widal test normal range. Read on to learn about what the Widal test is done for, as well as the Widal test procedure and interpretation.

Purpose Of The Widal Test

A Widal test is done to diagnose the possibility of having typhoid or paratyphoid fever. After you are exposed to an infection, i.e. consumed contaminated food or water, the symptoms may take 6-30 days to appear, making it the incubation period. Paratyphoid is less severe than typhoid among the two types of enteric fever.

The Widal test is a type of agglutination test that aims to discover the antibodies against two antigens (O and H) of the bacteria Salmonella enterica in a blood sample. Widal test positive means that your blood sample contains Salmonella antibodies and their reaction to any of the two antigens (O and H) leads to the formation of clumps. Widal test normal range can be checked in a slide as well as a test tube. However, experts prefer tube agglutination over slide agglutination to be sure about the titer or concentration of the antibodies. Here are the antigens used in the test:

• ‘H’ antigen of Salmonella Typhi
• ‘O’ antigen of Salmonella Typhi
• ‘H’ antigen of Salmonella Para typhi

It is wise to undergo the Widal test after the first week of the infection. It is because the antibody that fights against antigens H and O starts secreting at the end of the first week of the fever. It is recommended to provide two blood samples to be 100% safe with a gap of seven to ten days to understand how the antibody concentration is increasing.

What Is The Widal Test Normal Range?

If the titers of H and O antigens are less than 1:160, it is considered the Widal test normal range where the result will be negative [1]. Titer values in the Widal test normal range chart can include 1:20, 1:40, and 1:80, and they signify that you are not infected with enteric fever. 

Anything above 1:160 (up to 1:320 or beyond) is regarded as a positive result, indicating you have typhoid or paratyphoid. Note that the Widal test normal range can vary across labs.

How To Interpret The Results Of The Widal Test?

If you have an enteric fever, antibodies against Salmonella bacteria will appear in your serum at the end of the first week. A blood test at that time will lead to the formation of agglutination or clumping in the test tube or slide, which means that the antibodies in your body have reacted to the antigens used in the test. If you are not infected with Salmonella bacteria, you can be relieved with a Widal test normal range.

Remember, Widal test interpretation largely depends on the patient’s case history. If you have previously been exposed to typhoid antigens, it can affect the interpretation. The source of these antigens can be previous infections or vaccination.

Widal Test Procedure - Step by Step

A Widal test is performed like any other blood test. In usual cases, the blood will be collected in the following manner:

• You have to sit on a chair, and the concerned healthcare provider will locate a vein to draw blood in the joint opposite to your elbow
• After locating the vein, the area will be sanitized with cotton and alcohol swab
• Next, a vacutainer needle will be inserted into the vein; it will feel no more than a pinch
• Thereafter, the needle will be connected to a test tube to collect blood
• When the test tube is filled with sufficient blood, the needle will be removed from your hand. The healthcare provider will give you a cotton ball to press on the site in order to stop bleeding
• Once the pricked site no longer bleeds, they will apply a band-aid to prevent friction. However, you can remove the band-aid after some time

This complete process may take about five to ten minutes.

What Are The Risks Associated With The Widal Test?

Note that there are no significant risks associated with this blood test. The site from where blood is collected gets healed within five to ten minutes. It may only hurt a little when the needle is inserted. Widal test normal values also indicate zero risk. However, if you don’t get a Widal test normal range in the test result, make sure to go for an online doctor consultation to understand what is to be done for treatment.

How To Prepare For The Widal Test?

The Widal test can be conducted at any time, and it doesn’t need any special preparation, such as fasting. Just visit the concerned lab at a convenient time, provide your blood sample, and collect the report when it is available. You may get it the same day.

Conclusion

By knowing about the Widal test normal range and what the Widal test is used for, you can understand its significance if your doctor has recommended this test. 

Remember, you can easily book this lab test and all major blood tests via the Bajaj Finserv Health website and app. It saves precious time as you can book online lab tests from anywhere and visit the partner lab just to give your blood sample. Make sure to undergo timely health check-ups for a healthy and stress-free life ahead!