At a Glance
Why Get Tested?
To detect and diagnose a Bordetella pertussis infection
When to Get Tested?
When you have persistent, sharp spasms or fits of coughing (paroxysms) that the doctor suspects is due to pertussis (whooping cough); when you have symptoms of a cold and have been exposed to someone with pertussis
A nasopharyngeal (NP) swab or a nasal aspirate; occasionally, a blood sample taken from a vein in your arm
Test Preparation Needed?
No test preparation is needed.
The Test Sample
What is being tested?
This is a group of tests that are performed to detect and diagnose a Bordetella pertussis infection. B. pertussis is a bacterium that targets the lungs, typically causing a three-stage respiratory infection that is known as pertussis or whooping cough. It is highly contagious and causes a prolonged infection that is passed from person to person through respiratory droplets and close contact.
The incubation period for pertussis varies from a few days to up to three weeks. The first stage of the disease, called the catarrhal stage, usually lasts about two weeks and symptoms may resemble a mild cold. It is followed by the paroxysmal stage, which may last for one or two weeks or persist for a couple of months and is characterized by severe bouts of coughing. Eventually, the frequency of the coughing starts to decrease and the infected person enters the convalescent stage, with coughing decreasing over the next several weeks. Pertussis infection, however, can sometimes lead to complications such as pneumonia, encephalitis, and seizures, and it can be deadly. Infants tend to be the most severely affected and may require hospitalization.
Pertussis infections used to be very common in the United Kingdom, averaging over one hundred thousand cases per year, with major epidemics occuring every few years. Since the introduction of a pertussis vaccine and widespread vaccination of infants, this number drastically decreased to less than a thousand cases per year in the early 2000s. However, since neither the vaccine - nor the pertussis infection - confers lifetime immunity, health professionals are still seeing periodic outbreaks of pertussis in young unvaccinated infants, in adolescents, and in adults, most recently in 2012 when there were over 6000 recorded cases in England and Wales.
Pertussis testing is used to diagnose these infections and to help minimize their spread to others. Several different types of tests are available to detect pertussis infection. Some of these include:
- Detection of pertussis genetic material (Polymerase Chain Reaction, PCR)
- Direct fluorescent antibody (DFA)
- Blood tests for pertussis antibodies, IgA, IgG, IgM
- Detection of anti-pertussis toxin IgG antibodies in oral fluid
Pertussis can be challenging to diagnose at times because the symptoms that present during the catarrhal stage are frequently indistinguishable from those of a common cold or of another respiratory illness such as bronchitis, influenza, and, in children, Respiratory Syncytial Virus (RSV). In the paroxysmal stage, many adults and vaccinated patients who have pertussis will present with only persistent coughing. Suspicion of pertussis infection is increased in patients who have the classic “whoop,” in people who have cold symptoms and have been in close contact with someone who has been diagnosed with pertussis, and when there is a known pertussis outbreak in the community. A swab for pertussis culture and/or PCR test will usually be sent from these patients but should not be performed on close contacts that do not have symptoms.
How is the sample collected for testing?
Sample collection technique is critical in pertussis testing. For a culture and/or a test for genetic material, a nasopharyngeal (pernasal) swab or aspirate is used. The nasopharyngeal swab is collected by having you tip your head back and then a Dacron swab (like a long cotton bud with a small head) is gently inserted into one of your nostrils until resistance is met. It is left in place for several seconds, then rotated several times to collect cells, and withdrawn. A nasopharyngeal aspirate is taken by using a syringe or other suction device to insert and immediately withdrawing a small amount of saline into your nose while your head is tipped back. Neither procedure should be painful, but it may tickle a bit, cause your eyes to water, and provoke a coughing reaction. Whenever possible, samples should be collected before you are given any antibiotics.
For antibody testing, a blood sample is obtained by inserting a needle into a vein in the arm.
Oral fluid is collected by brushing a swab along the gums. This can be done by a health professional, by the patient themselves or the patient’s parent or guardian.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.