Whooping cough, medically known as pertussis, is a highly contagious bacterial infection that affects the respiratory tract. While it’s commonly associated with children, it can affect people of all ages, especially those with weakened immunity. Early and accurate diagnosis of whooping cough is critical to ensure timely treatment and prevent its spread.
Despite the availability of vaccines, whooping cough has been making a comeback in many regions due to waning immunity and incomplete immunization. Because early symptoms can easily be mistaken for other respiratory infections like the flu or bronchitis, accurate and timely diagnosis is crucial.
What Is Whooping Cough?
Whooping cough is caused by the bacterium Bordetella pertussis. The infection begins with symptoms similar to the common cold such as runny nose, mild fever, and sneezing but can progress into severe coughing fits followed by a high-pitched “whoop” sound as the person breathes in. These coughing episodes can be intense enough to cause vomiting, broken ribs, or exhaustion.
Because its early symptoms mimic other respiratory infections, whooping cough is often misdiagnosed, especially in older children and adults. That’s why understanding the diagnostic process is so important.
Why Early Diagnosis of Whooping Cough Matters
An early diagnosis of whooping cough not only helps in managing the disease effectively but also limits the chance of spreading the infection to others. This is especially crucial for infants under 6 months who are too young to be fully vaccinated and are at the highest risk for complications like pneumonia, seizures, and even death.
When whooping cough is caught in its early stages, antibiotics can be more effective, and symptoms may be milder. Moreover, early treatment can reduce the contagious period, making it safer for those around the patient.
Clinical Evaluation: First Step Toward Diagnosis
The diagnosis of whooping cough usually begins with a clinical evaluation. The doctor will review your symptoms and medical history, and perform a physical examination. Key signs that raise suspicion of pertussis include :-
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Severe, repetitive coughing spells
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A characteristic “whooping” sound during inhalation
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Post-cough vomiting
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Symptoms lasting more than a week with no improvement
In infants and some adults, the “whoop” may not be present, making diagnosis more challenging. In such cases, lab tests become essential.
Laboratory Tests for Whooping Cough
If a doctor suspects whooping cough based on symptoms, they may order one or more of the following diagnostic tests :-
- Nasal or Throat Swab Test (PCR or Culture Test) :- The most common test for diagnosing whooping cough is a polymerase chain reaction (PCR) test, performed on a swab taken from the back of the nose or throat. This test detects genetic material from the Bordetella pertussis bacteria and provides results within a few hours to a day. A culture test is another method, where the swab is sent to a lab and observed for bacterial growth. While this test is highly specific, it takes several days to deliver results and may not detect the bacteria in later stages of infection.
- Blood Tests :- Blood tests are less commonly used but may be recommended in older patients or during later stages of infection. These tests look for elevated white blood cell counts, especially lymphocytes, which can suggest an ongoing pertussis infection.
- Serology (Antibody Test) :- Serology tests detect antibodies against Bordetella pertussis in the blood. This test is more useful in adolescents and adults who may have had symptoms for several weeks. However, it’s not as effective in early diagnosis or in children.
Who Should Get Tested?
Doctors typically recommend testing for whooping cough if :-
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You or your child has had a persistent cough lasting more than two weeks
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You’ve been in contact with someone diagnosed with pertussis
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A newborn or young child in your household develops coughing fits
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You’re a pregnant woman showing symptoms, especially in the third trimester
Testing is also prioritized during outbreaks in schools, daycare centers, or healthcare facilities.
Challenges in Diagnosis of Whooping Cough
Diagnosing whooping cough isn’t always straightforward. In its early stages, it resembles a cold or flu, making it easy to overlook. In vaccinated individuals, symptoms might be milder, leading to further confusion. Additionally, some adults and teens may never develop the hallmark “whoop” sound, which delays diagnosis.
The timing of testing also plays a role. PCR tests are most effective during the first 2–3 weeks of coughing. After that, their accuracy drops significantly. Culture tests can also return false negatives if the bacteria are no longer present in the upper airway.
Due to these limitations, doctors often rely on a combination of clinical history, physical examination, and test results to make a diagnosis.
What to Expect During Testing?
If your doctor suspects whooping cough, they may perform a nasopharyngeal swab, which can be slightly uncomfortable. A thin swab is inserted into your nostril and rotated to collect a sample from the back of your nasal passage. This may cause brief discomfort or a watery eye, but the procedure is quick.
If a blood sample is needed, it’s drawn from a vein in your arm, as with any standard blood test.
Most results from PCR tests are available within 24–48 hours, helping initiate timely treatment.
Follow-Up After Diagnosis
Once whooping cough is confirmed, treatment typically involves a 5-day course of antibiotics, usually azithromycin or clarithromycin. Early treatment may help shorten the illness and reduce contagiousness. For household contacts or people at high risk (like infants), preventive antibiotics might be recommended even if they don’t show symptoms.
Patients are generally advised to stay home for at least five days after starting antibiotics to prevent spreading the disease.
Preventing Further Infections
Vaccination is the best defense against whooping cough. The DTaP vaccine protects infants and children, while the Tdap booster is recommended for teens, adults, and pregnant women during each pregnancy.
For individuals diagnosed with whooping cough, it’s vital to avoid close contact with infants, wear a mask, and maintain good hygiene until the infection subsides.
Conclusion
Whooping cough can be a serious illness, especially in infants and unvaccinated individuals. Early diagnosis is essential for effective treatment and to protect those around you. If you or your child experiences a persistent cough that worsens over time or includes vomiting, choking, or a “whoop” sound, don’t delay consult a healthcare provider and get tested.
