test Details

Salmonella typhi, Paratyphi

The human body is programmed to consume clean food and water. But if a person consumes unclean water or food, the contamination in it can attack the body. Contaminated food substances contain various germs, viruses, and bacteria. These foreign substances affect the body’s general functioning and immunity.

Typhoid is a fever caused by the consumption of contaminated food and water. It contains the bacteria Salmonella typhi which can cause an acute illness. Salmonella paratyphi is also one of the bacteria that can cause typhoid fever but at a less severe scale.

These bacteria can contaminate food sources after being carried by a human carrier who was in contact with the bacteria. The bacteria that enter the body starts multiplying and is carried through the body attached to white blood cells. The bacteria reach the liver, bone marrow and spleen, thus resulting in typhoid fever.

The Typhi IgG test is a test used to check for antibodies against salmonella typhi. Salmonella typhi is the bacteria responsible for typhoid fever. The test checks for the levels of immunoglobulin G (IgG) to provide a positive or negative result on the presence of salmonella typhi in the body. Typhi IgG and IgM tests are conducted together to test the presence of antibodies IgG and IgM in the blood.

Typhoid is endemic in India. Poor hygiene practices and the excessive population are major causes of concern. Typhoid spreads through contaminated food and water, and in India, the majority of the population does not have access to safe and clean drinking water. Children are more susceptible to typhoid due to their lower immunity.

Other names of the typhi IgG test

• Typhidot IgG test
• TyphiDot IgG

What does the typhi IgG test detect/measure, and who is this prescribed for?

The typhi IgG test measures the levels of antibodies against Salmonella typhi in the blood.

A typhi IgG test is ordered when a patient is experiencing symptoms of typhoid fever. The typhi IgG and IgM test provide the levels of immunoglobulin G and immunoglobulin M antibodies against Salmonella typhi in the blood. Typhoid fever spreads in the body for one to two weeks, and the total duration of the fever is around three to four weeks. The early symptoms of typhoid fever IgG are as follows:

• Weakness
• Thirst
• Fatigue
• Sweating
• Stomach pain
• Loss of appetite
• Weight loss
• Diarrhoea
• Rash
• Dry cough

The later stages of typhoid bring on even more severe complications, such as becoming delirious and in a typhoid state. Typhoid state is the state of the body in which the infected lies motionless and fatigued with their eyes half-closed. During the later stage, the disease can become fatal and cause life-threatening complications. Even if the fever subsides, there is a possibility of the fever returning.

Patients with the above-mentioned conditions and symptoms are prescribed tests such as typhi IgG and IgM and widal test among other tests to diagnose the condition and confirm the presence of bacteria such as salmonella typhi and salmonella paratyphi.

The typhi IgG/IgM test does not provide quantitative values to the results. It is a qualitative rapid test that proves the presence of immunoglobulin G and immunoglobulin M in the blood test. The test provides results as positive or negative.

The results of a typhi IgG test are given out as positive or negative. There are two antibodies - immunoglobulin G (IgG) and immunoglobulin M (IgM) in the blood. These antibodies are created by the body to fight typhoid fever caused by salmonella typhi. The typhidot test checks for both of these antibodies as it provides an idea about the stage at which the infection is currently.

There are 3 bands present in the typhidot test cassette. The three indicators are denoted by C, G, and M. G stands for antibody IgG, and M stands for antibody IgM. The test can provide the following results:

● Negative or non-reactive result: In this result, only the C band turns burgundy, whereas there is no band seen on G and M. This result means there is no presence of antibodies IgM and IgG which in turn means the absence of typhoid-causing bacteria in the body.

● Positive or reactive result: In this result, there can be a variety of outcomes.

1. The C band and G band turn burgundy. This means there is a presence of antibody IgG in the body.

2. The C band and M band turn burgundy. This means there is a presence of antibody IgM in the body.

3. The C band, M band and G band turn burgundy. This means there is a presence of both IgG and IgM antibodies in the blood.

● Invalid result: If no C band is developed, this means the test has not been done properly.

There should be a C band present in the test irrespective of the G and M bands to prove the test was done properly. In case of an invalid result, the test needs to be done again to get a result.

One thing to note is that the typhi IgG/IgM test is not conclusive. This means this is just used as a basis for further testing by the physician. This is a more rapid and easy-to-interpret test than a Widal test.

A typhi IgG test is conducted through blood samples procured through a general blood test.

Test Preparation

Before the test

The typhi IgG test requires no special preparations before the test.

During the test

The typhi IgG test is done through blood samples. For extracting the sample, a medical health professional will wrap a belt around the patient’s arm. Then the blood will be extracted from the vein through a sterilized needle into a small vial. The vial is then used to run tests. This process is completed within a short span of time of usually 5 mins.

After the test

After the blood sample is submitted, there are no special procedures to be followed.

Test inclusions: What parameters are included?

The typhi IgG and IgM test provide the levels of immunoglobulin G and immunoglobulin M antibodies against Salmonella typhi in the blood. The test provides the results as negative or positive as it is not a quantitative test. It is used as a screening test and is ordered along with other tests to confirm the presence of salmonella typhi in the blood.

This test is a simpler test in comparison to other tests such as the Widal test. It provides rapid results and is used as a basis for further tests. IgM positive or IgG/IgM positive suggests the body is currently infected, whereas an IgG positive means the infection is in a later stage or the host has been infected previously by salmonella typhi.

How frequently should you take this test?

A typhi IgG test is required to be taken when the patient has symptoms of the following conditions:

• Lethargy
• Diarrhoea
• Aches and pains
• Headaches
• Poor appetite
• Chest congestion
• Abdominal pain

The typhi IgG test is prescribed by the doctor in the presence of the above-mentioned symptoms in the patient. Typhoid fever is constant and usually comes down in the third or fourth week.