Widal test is one way to diagnose typhoid. This examination is still widely carried out in Indonesia because it is practical, fast, easy, and cheap.
Typhoid is also known as typhoid or typhoid fever. Of the 11-20 million cases of typhus per year in the world, Indonesia along with other Southeast Asian countries are recorded to have the most cases of typhus. This disease is characterized by fever accompanied by digestive disorders, such as constipation or diarrhea.
Function of the Widal Test for Typhoid Diagnosis
Typhoid is caused by a bacterial infection Salmonella. These bacteria can be found in foods that are not cooked properly, or are not processed hygienically.
When bacteria Salmonella enters the human body, the body's defense system will respond by producing special antibodies to fight bacteria Salmonella. The Widal test is performed to determine the amount of these antibodies. An increase in the number of these antibodies can indicate the occurrence of typhoid.
How to Take and Read the Widal Test
When the symptoms that appear are suspected to be due to typhus, the first stage of diagnosis that doctors do is to trace the history of the disease. The doctor will ask about the cleanliness of food and housing, as well as a history of the appearance of complaints experienced.
Then the doctor will perform a physical examination, including checking body temperature, seeing the appearance of the surface of the tongue, examining which part of the stomach is painful, and listening to bowel sounds.
To determine whether the patient has typhus, one type of test that can be recommended by doctors is the Widal test. In the Widal examination, the patient will be asked to undergo a blood drawing process. After that, the blood sample will be sent to a laboratory for examination.
In the laboratory, the blood sample will be dripped with bacteria Salmonella which have been killed in the form of O antigens (bacterial bodies) and H antigens (bacterial tails or flagella). These two test materials are needed because the antibodies for the bacterial body and the bacterial flagellum are different.
Next, the blood sample is diluted tens to hundreds of times. If, after being diluted many times, antibodies against Salmonella tested positive, the patient can be considered to have typhoid fever or typhoid.
However, the standard reading of this test varies in different regions, depending on the level of endemic typhus in that region. In Indonesia, Widal readings can generally be considered as strong data to support the diagnosis of typhoid, when antibodies Salmonella still found at dilutions of 320 times (1:320) or more.
The diagnosis of typhoid can be confirmed through a repeat Widal test, which is performed 5-7 days after the first test. The patient is declared positive for typhoid if the antibody count is Salmonella increased to four times compared to the first test.
Are Widal Test Results Accurate?
The Widal test is actually quite accurate, but there are several factors that can affect its level of accuracy. Some of these are the quality of the blood sample and the antigen used, or the way in which the test results are examined and read.
In addition, a person can get a positive result on the Widal test even though he does not have typhus. This can happen if the patient is a carrier (carrier) of the bacteria that causes typhus or has recently been vaccinated against typhus. People who have recently recovered from typhus can also get a positive result, because of the antibodies against the bacteria Salmonella can remain in the body for up to two years.
On the other hand, a negative Widal result does not necessarily indicate a person does not have typhus. This condition can occur due to poor nutrition, long-term consumption of drugs, or suffering from certain diseases that reduce the body's resistance.
The Widal test is a quick and easy diagnosis of typhoid in areas with limited health facilities. However, in some conditions, the Widal test can give false positive or false negative results.
For more accurate results, the doctor may suggest other diagnostic tests, such as the TUBEX test, which can be performed in a hospital or laboratory with adequate facilities. So if you experience symptoms of typhoid, don't hesitate to consult a doctor so that a proper examination can be carried out and given treatment.