Enteric Fever:- Part 3 – Typhidot Test for Diagnosis of Typhoid fever
November 2, 2022Lab TestsMicrobiology
- Venous blood is taken to get the serum.
- The main indication is to diagnose Typhoid fever.
Test principle of Typhidot Test
- This test detects antibody IgG and IgM in the serum of the patient.
- The commercial kit manufacturer claims that Typhidot can detect antibodies in the first few days of fever when Widal is negative.
- The Typhidot is easy to perform and requires no special equipment.
- Typhidot will be a useful complementary test to blood culture and the Widal test in typhoid fever diagnosis.
- The widal test is positive after at least 7 to 10 days of Typhoid fever.
Result accuracy of Typhidot
- This rapid test accuracy is not clear.
- The Typhidot test gave a sensitivity of 100 percent and specificity of 80 percent when bacteremic patients were analyzed.
- Another study shows the test’s sensitivity and specificity using blood culture as the gold standard were 92.3 % and 98.8 %, respectively, for typhoid fever.
- One study was done in Pakistan.
Interpretation of the Typhidot test result:
|IgM||Acute typhoid fever|
|IgM + IgG||Acute typhoid fever|
|IgG only + IgM (negative)||Past infection|
Typhidot test advantages:
- Typhidot is easy to perform.
- There is no need for any equipments.
- There is no need to train the laboratory staff.
- This may be a useful complimentary test to the widal test and blood culture.
- NOTE: My personal experience is that widal is still a better option and more reliable than Typhidot because Typhidot false-positive results are very common.
Question 1: What is the difference between Typhidot and widal test?
It is claimed that typhidot will be positive early than the widal test.
Question 2: When will widal test be positive in typhoid fever?
Widal test will become positive after 7 to 10 days.