What is Typhoid fever?
A disease condition which is an acute, life threatening fever causing illness i.e. transmitted via ingestion of water or food being contaminated with feces of an infected person. The causative agent is Salmonella typhi or S. paratyphi. It produces symptoms like diarrhea (loose motions), rose colored rashes & progressive fever.
What is typhidot IgG lab test?
This test is indicated in diagnosis of typhoid fever. It is also known as Widal test and looks for IgM and IgG antibodies in blood released against OMP (outer membrane protein) of Salmonella typhi. In this test by using ELISA (enzyme linked-immunosorbent assay) technique we look for Immunoglobulin G (IgG) antibodies which are released after some time but stay in the body for a long time.
Why is typhidot IgG by elisa lab test done?
The test is done:
- When person showing typhoid fever symptoms like headache, cough, gastroenteritis, gradual increase in fever as high as 40 degree C, intestinal hemorrhage, rash of flat/rose colored spots etc.
- As it helps diagnose typhoid fever by looking for IgG and IgM antibodies against Salmonella typhi
- Presence of IgG antibodies indicates a past infection with Salmonella typhi
- As it both qualitatively and quantitatively determines antibodies against Salmonella typhi
- It can give titers (concentration) of specific antibodies
- It aids in identification, diagnosis & monitoring of fever and other salmonella infections.
- When does Typhidot turn positive?
The Typhidot test is expected to turn positive within 2 to 3 days of contracting an infection.
- What is negative diagnosis?
It means that for whatever reason the test was indicated/ performed, it was unable to find that component in the sample.
- What appears first IgG or IgM?
IgG appears in body fluids after an infection or immunization. While IgM found in blood and lymph fluid appears firstly when the body fights a new infection.
- Which is the most accurate way of testing typhoid fever?
It can be diagnosed accurately via a bone marrow sample for typhoid fever.
- What is meant by O and H in widal test?
In Widal test, antibodies against H (flagellar) & O (somatic) antigens are measured. O antibody appear first and later fall/disappear within months in acute infection. H antibody appears later in the infection but stays for longer.
INTERPRETATION OF THE RESULTS:
Different laboratories have got different sensitivity and specificity results for Typhidot IgG antibodies.
- Seropositive: simply means that antibodies against Salmonella typhi present and indicates to past infection. It also suggests that person is immune to the infection
- Seronegative: means that person hasn’t had typhoid fever (not always necessary) and are prone to the infection in the future.
You get tested for diagnosis of remote or past infection with Salmonella typhi.
