Pertussis

Other names: Bordetella Pertussis Culture; Whooping Cough Tests; Bordetella Pertussis Antibodies; Bordetella Pertussis by PCR; IgA, IgG, IgM; Bordetella Pertussis by DFA

The pertussis test is used to test for the presence of an infection caused by Bordetella pertussis; this is a form of bacteria, which attacks the lungs and causes a three-stage infection, which is commonly known as whooping cough. Whooping cough is a serious respiratory illness, which is highly contagious and passes from person to person through the transfer of droplets via sneezing and coughing. The incubation period for pertussis is between three days and three weeks and symptoms vary, according to the stage of the illness; the first stage is known as the catarrhal stage, the second stage is the paroxysmal stage and the third stage is known as the convalescent stage. Symptoms start like those associated with a common cold and progress to a very severe cough, which often comes in bouts.

Nowadays, whooping cough is rare thanks to the routine vaccination programme in the UK; all babies are vaccinated against pertussis.

Why is the test used?

The test is used to diagnose a pertussis (whooping cough) infection. There are many tests which may be ordered to test for the infection, including culture tests, blood tests (to test for antibodies) and the PCR (polymerase chain reaction) test. It is important to diagnose the infection early so that treatment can be administered and the spread of the infection can be stopped.

The test is usually ordered with a patient has symptoms of a pertussis infection; symptoms include:

• Symptoms including coughing, a runny nose, sneezing, head and muscle aches and a high temperature, which are usually associated with a common cold. These symptoms appear during the catarrhal stage.
• Severe bouts of coughing, which may cause the patient to vomit and rapid coughing fits, which cause the patient to make a ’whooping noise’ between coughs (hence the name of the condition). These symptoms appear during the paroxysmal stage.

How is the test performed?

There are many different types of test that can be carried out to detect the presence of a pertussis infection.

The blood test is used to detect the presence of antibodies to the pertussis infection; the test is done by taking a sample of the patient’s blood. A needle is inserted into a vein in the arm (usually on the inside of the elbow) and the blood is collected in a syringe. Once the doctor or nurse has a sufficient sample, the blood will be bottled, labelled and sent to the laboratory for analysis.

What do the test results show?

A positive culture result indicates that a patient has been exposed to the pertussis infection.

If the results of the blood antibody test show that both IgM and IgG antibodies are present in the blood, this means that the patient has either an active or a very recent infection. If only IgG antibodies are present, this may indicate a recent infection; antibodies are also present after a vaccination.