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No specific preparation needed
Typhoid Test (Widal test) is a blood test which identifies Enteric fever (Typhoid fever and Paratyphoid fever). Enteric fever is a systemic infection triggered by means of bacteria, generally through ingestion of contaminated food or water. This test is carried out with the use of the Tube agglutination method.
The test is performed to detect Enteric fever (Typhoid and Paratyphoid fever).
The typhoid test measures the titres of antibody in opposition to the bacteria which leads to Enteric fever. Enteric fever is brought about by bacterial infection and is of two types:
Typhoid fever - It is induced through Salmonella enterica serotype Typhi (S. Typhi).
Paratyphoid fever - It is induced through Salmonella enterica serotypes Paratyphi A (S. Paratyphi A), Paratyphi B (S. Paratyphi B) or Paratyphi C (S. Paratyphi C).
Typhoid and paratyphoid fever are usually gotten when you consume food or water, contaminated by means of faeces of an acutely convalescent individual (recovering from disease) or a chronic, asymptomatic carrier.
The incubation length (the time interval between exposure to an infection and the surfacing of the first symptoms) of Enteric fever is 6-30 days. Typhoid fever has a gradual start. In the beginning, there is a growing feeling of fatigue alongside with a fever which will increase with each passing day. By the fourth or fifth day the fever may change from low-grade to as high as 102°F–104°F (38°C–40°C). Known as the Stepladder fever pattern, this used to be the hallmark symptom of Typhoid however, is now witnessed in very few cases. The patient may as well go through a headache, weakness, and loss of appetite. Abdominal pain, diarrhoea, or constipation is common but not threatening. A transient rash of rose-colored spots can sometimes be viewed on the trunk (Rose spots).
The sickness can stay for a month, if untreated. Early detection and treatment are necessary as life-threatening complications of typhoid fever normally happen after 2–3 weeks of sickness and may cause intestinal bleeding or perforation.
If the antibody against Salmonella is existing in patient’s serum, it will react with the particular antigen in the reagent and give clear agglutination at the bottom of the test-tube after approximately 18 hrs. The best dilution of the patient’s serum sample that offers a clear agglutination with the Widal test antigen suspensions is the antibody titre. The serum sample which displays the titre of 1:80 or more for O agglutination and 1:160 or more for H agglutination shows active infection. An increase in titres (4-fold or more) in the two blood samples taken 10 days separately confirms the diagnosis. Please note that different labs may different reference values for the interpretation of the Widal test. The interpretation of a typhoid test (Widal test) is extensively influenced by the nature and extent of the patient’s preceding contact with typhoid antigens. It can be both due to clinical or subclinical infections with typhoid or related organisms or from typhoid vaccination.
This test is carried out on a blood sample. A syringe with a exceptional needle is used to withdraw blood from a blood vessel in your arm. The healthcare issuer will tie an elastic band around your arm to make the blood vessels swell with blood. This makes it easier to withdraw blood. You may as well be requested to tighten your fist. Once the veins are really visible, the place is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to take the sample. You will feel a tiny pinprick in the course of the procedure. Blood sample once taken will then be sent to the laboratory.
There is no risk related with the test. However, in view that this test entails a needle prick to withdraw the blood sample, in very uncommon cases, an affected person may experience increased bleeding, hematoma formation (blood series below the skin), bruising or infection at the place of needle prick.
Inform the medical doctor about the medicines you may have been taking. No specific preparations are needed prior to this test.
Widal test can be carried out by way of the following two specific methods:
1. Quantitative Slide Test Qualitative Slide Test Slide agglutination Widal test
2. Tube agglutination Widal test. Tube agglutination is the endorsed method as it has more accuracy. However, Slide agglutination is preferred some as it offers the fast result.
Tube agglutination method requires about 18 hours for test completion.
The limitations of Widal test are:
Previous typhoid vaccination may cause multiplied antibody titres in the non-infected individuals False positive Widal test can occur in petients with non-enteric Salmonella infection, for instance Typhus, Immunological disorders, chronic liver disease, Malaria and cryptococcal meningitis Prior use of antibiotics can have an effect on antibody response giving a low titre in the Widal test even in the presence of bacteriologically verified typhoid fever The Widal agglutination titre varies with the geographic region primarily based on the incidence of Salmonella infection in that place Past infection with serotype Typhi or any other nontyphoidal Salmonella serotype as well result in false positive Widal test
Avoiding contaminated food and drinks can assist to prevent typhoid fever. Along with that, appropriate vaccination against typhoid fever can as well keep a check on having any possible case of infection.
The other tests which are used to diagnose Enteric fever cover Blood lifestyle test, Widal test, Stool culture test, and Urine culture test. Among these, blood culture is the most regularly recommended method for diagnosing Enteric fever and is carried out during the first week of fever. If in case other tests results come inconclusive, then bone marrow samples can be used to diagnose any infections.
Q. What is the suitable time during illness for carrying out this test?
Widal test needs to be done after first week of fever. The reason being, the antibodies against “O” and “H” antigens of Salmonella begin to show in the blood of patients by the end of 1st week, with sharp rise in second and third week and the antibody titre remains steady till fourth week after which it may start declining. It is preferable to test two blood samples at an interval of 7 to 10 days to prove rising antibody titres.
Disclaimer: The information provided herein is for patient general knowledge only and should not be used during any medical emergency, for the diagnosis or treatment of any medical condition. Duplication for personal and commercial use must be authorized in writing by Surjen.com.
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