The Widal test report, or typhoid test report, is usually performed to identify typhoid fever. It is caused by Salmonella Typhi bacteria, which is transmitted via contaminated food and water. Due to the similarity of symptoms with other illnesses, an accurate diagnosis of typhoid fever requires proper testing. A Widal test is a serological test used to detect antibodies against bacteria in a patient's blood sample to identify the presence or absence of bacterial infection.
What is a Widal Test?
The Widal test is a blood test that helps confirm or rule out typhoid fever, especially in cases with mild symptoms. Fever typically appears 6 to 30 days after exposure to a pathogen because it takes time for the body to form antibodies. The Widal test is more accurate if it is performed at least one week after symptoms begin. This test detects antibodies against the flagellar (H) and somatic (O) antigens that are associated with typhoid fever. If you have these antigens, your body will make bacterial-specific antibodies in response to the antigens. The Widal test examines how antigens and antibodies in a person's blood sample are able to interact. By identifying the presence of these antibodies, the test can determine if an individual has been exposed to the bacteria responsible for typhoid fever.
Who Should Get a Widal Test?
Typhoid fever can lead to severe health complications if left untreated. If you experience the below symptoms, a healthcare provider might suggest a Widal test in order to verify the diagnosis.
Fever and body aches: A typhoid infection may cause a severe fever ranging from 103 to 104 °F, persisting for several days, along with symptoms such as headaches and body pains.
Abdominal symptoms: Patients with typhoid fever may experience abdominal discomfort, pain, and tenderness. The patient may have constipation in the beginning and later develop diarrhea.
Red-coloured spots over the body: The appearance of red spots on the body, especially on the lower part of the chest or in any other region, is common. These red spots may disappear when pressure is applied and then reappear.
Reduced appetite and energy levels: Typhoid fever can reduce appetite and energy levels, leading to weight loss. Weakness and tiredness may occur, making patients incapable of performing routine tasks.
Symptoms of severe typhoid fever: Severe cases of typhoid fever may manifest symptoms including delirium, agitation, confusion, and hallucinations. In such serious infection cases, medical attention is required immediately.
Widal Test Procedure
The process of the Widal test:
A small sample of blood is taken from the patient and allowed to coagulate. After this step, the serum, known as the liquid part of the blood, is separated from the clot using a centrifuge.
Antigen is obtained from bacteria, which are responsible for causing typhoid fever. This substance is prepared by growing the bacteria in a special culture medium. Serum is then mixed with different dilutions of the prepared antigen in a series of test tubes, each containing a different dilution of serum, and incubated at a temperature of 37 °C for 16-18 hours.
After the incubation period, the tubes are examined for bacterial clumping or agglutination. If agglutination is noted at a particular serum dilution, it means that the patient has developed antibodies against that particular bacterium at this specific dilution. The antibody titer is recorded as the highest dilution of serum at which clumping is observed.
The patient's antibody titers are compared with a standard reference range to interpret the results. A titer of 1:160 or higher will be indicative of a typhoid fever diagnosis. It should be noted, however, that the Widal test alone cannot be used for identifying typhoid fever, and other clinical and laboratory tests are required for confirmation of typhoid infection.
The Range for Widal Test Results
A Widal test is done to diagnose typhoid fever, the results of which are given in the form of a titer ranging from 1:20 to 1:640. A titer of 1:160 or above is considered positive, and this does not always mean that an individual has an active infection because these antibodies can persist for a long time even after the infection is treated. Therefore, detailed clinical findings based on symptoms and medical history are also important to consider. Early diagnosis, followed by appropriate antibiotic treatment, decreases the complications associated with illness and reduces the transmission rate.
Positive Result on a Widal Test
If an individual gets a positive result from the Widal test, it means they have been infected with the Salmonella Typhi bacteria. It is important to treat any positive Widal test results seriously and adhere to the healthcare provider’s recommendations.
Negative Result on a Widal Test
If an individual gets a negative result from the Widal test, it means they have antigen O and H titres of less than 1:160, suggesting that they do not currently have typhoid fever and that their symptoms could be due to another type of infection.
Typhoid fever is a condition caused by the bacterium Salmonella Typhi. It leads to symptoms such as high fever, gastrointestinal issues, abdominal pain, and diarrhea. The infection caused by this bacterium can be effectively managed with antibiotics. Without proper treatment, it can lead to significant harm to various organs in the body. A Widal test is often used to determine the presence of typhoid fever based on an agglutination reaction when antigens in the reagent interact with antibodies in the blood (serum). Immunization against typhoid fever is the most effective method of typhoid disease prevention.
