Widal / Typhoid Test (Typhidot) Lab Test

Widal / Typhoid Test (Typhidot)

Clinical Definition of Widal / Typhoid Test (Typhidot)

Typhidot is a rapid serological test for the diagnosis of typhoid fever. Typhidot test is a dot ELISA kit that detects IgM and IgG antibodies against the outer membrane protein (OMP) of the Salmonella typhi. The typhidot test becomes positive within 2-3 days of infection and separately identifies IgM and IgG antibodies. The test is based on the presence of specific IgM and IgG antibodies to a specific 50KD OMP.

Typhoid fever or enteric fever is an acute, life threatening and fever causing illness transmitted by the ingestion of food or water that has been contaminated with the feces of a person infected with the bacteria Salmonella typhi or S. paratyphi. Typically typhoid is accompanied by diarrhea, progressive fever and rose colored rashes. There are two commonly used screening tests which detect antibodies to the bacterium. The Widal test is both quantitative as well as qualitative and it can tell the titres of specific antibodies. The typhidot separately identifies IgM and IgG antibodies against the bacteria. IgM shows recent infection where as IgG signifies remote infection. The Typhidot test only gives result as positive or negative.

 

When do you expect results?

24 to 36 Hours

Why Get Tested?

The typhoid screening test is a used to identify, diagnose & monitor of fever and other salmonella infections. This is conducted to detect antibodies against the infection.

Reason to take Widal / Typhoid Test (Typhidot) Test

 

Typhoid fever is characterized by

Headache
Cough
Gradual increase in fever as high as 40 °C (104 °F)
Gastroenteritis
Non-bloody diarrhea
Rash of flat, rose-colored spots (rarely)
Intestinal hemorrhage in severe cases
Relatively abnormal slow heart beat
Excessive sweating
Enlarged spleen and liver 
Distended abdomen

 

Preparations Needed for Widal / Typhoid Test (Typhidot) Test

No Fasting Required. No other special preparations required.

Sample Required?

Specimen type: Serum (Blood Sample) , Specimen collection procedure : Venipuncture - Collection of blood from a vein, usually from the arm.

Understanding results of Widal / Typhoid Test (Typhidot)

Reference RangeInterpretation
No agglutination(Widal)Negative(Typhidot)
No infection(Widal)No infection(Typhidot)

 

‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Inference: The Widal test is not a very specific test, since patients are often exposed to other bacteria (e.g. Salmonella enteritidis, Salmonella typhimurium and some types of E. coli) in this species that induce cross-reactivity; many people have antibodies against these enteric pathogens, which also react with the antigens in the Widal test, causing a false-positive result. Test results need to be interpreted carefully in the light of past history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world.An antigen titer of more than 1:80 indicates an active infection. A single Widal test is of little clinical relevance due to the number of cross-reacting infections, including malaria.Demonstration of rising titres is a confirmatory.

 

References

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177418/
  2. https://phinvads.cdc.gov/vads/ViewValueSet.action?oid=2.16.840.1.114222.4.11.4218
  3. http://www.ncbi.nlm.nih.gov/pubmed/7342378
  4. https://cvi.asm.org/content/19/11/1833
  5. http://www.downtoearth.org.in/news/10minute-typhoid-test-38903
  6. http://www.ncbi.nlm.nih.gov/pubmed/12592993
  7. http://www.cochrane.org/CD008892/INFECTN_accuracy-rapid-diagnostic-tests-detecting-typhoid-and-paratyphoid-enteric-fever