Pertussis, commonly known as whooping cough, is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. Although often associated with the characteristic high-pitched “whoop” heard in children, this sound is frequently absent or muted in vaccinated teenagers and adults. This difference often leads to misdiagnosis and allows the infection to spread, as adults may not suspect they have pertussis. While generally milder than in infants, the adult infection presents as a persistent, severe cough that can be debilitating and serves as a reservoir for transmission to vulnerable populations.
The Missing Whoop Sound in Adults
The classic “whoop” is a distinct, high-pitched gasp for breath following a prolonged, exhausting fit of coughing. This sound occurs when a person inhales rapidly through swollen and narrowed airways after expelling all air from their lungs during a paroxysm.
In adults and adolescents, this signature sound is often missing due to partial immunity. Childhood vaccination provides protection, even if immunity wanes, resulting in a milder infection. Furthermore, the larger, more developed airways in adults do not become as severely constricted as those in infants. This physiological difference prevents the restricted intake of air that creates the whooping noise. For many adults, the infection presents as a cough that lasts for an unusually long time, often mistaken for bronchitis or a common cold.
Characteristics of the Adult Pertussis Cough
The most distinctive feature of pertussis in adults is the coughing fit itself, known as a paroxysm. These episodes are characterized by a series of rapid, forceful coughs delivered without any breath in between.
A person experiencing a paroxysm may feel a sudden sense of strangulation or suffocation while attempting to clear their airways. The fits are often violent, uncontrollable, and can occur without warning, sometimes causing temporary loss of consciousness (syncope) due to lack of oxygen. The paroxysm may end in a deep, rattling, or choking sound as the person struggles to draw a breath. This extreme effort can also cause post-tussive emesis, or vomiting, which is a strong indicator of the infection. The cough’s persistent, hacking, and repetitive nature frequently causes complications like cracked ribs or urinary incontinence.
Other Symptoms and Disease Timeline
Pertussis infection progresses through three recognized stages. The catarrhal stage lasts one to two weeks, during which symptoms mimic a common cold, including a runny nose, sneezing, a low-grade fever, and a mild cough. This initial phase is when the patient is most contagious, as the bacteria multiply in the respiratory tract.
The infection then advances to the paroxysmal stage, where severe, characteristic coughing fits begin. This stage typically lasts one to six weeks, sometimes extending longer. Associated symptoms include extreme exhaustion following the bouts and turning red in the face.
The final phase is the convalescent stage, marked by a gradual decrease in the frequency and severity of the paroxysms. A lingering non-paroxysmal cough may persist for several months during this recovery period.
Diagnosis and Management
Diagnosing pertussis in adults requires a high degree of clinical suspicion because classic symptoms are often absent. Confirmation is primarily done through laboratory testing, often involving a nasal or throat swab. Polymerase chain reaction (PCR) testing is highly sensitive and preferred, especially within the first four weeks of the cough’s onset.
Treatment typically involves specific antibiotics, such as macrolides like azithromycin or clarithromycin, which eradicate the B. pertussis bacteria. To reduce the severity and duration of symptoms, medication must be administered early, ideally within the first week of the cough. Even when started later, antibiotics are crucial for reducing the risk of transmission to others. Patients should isolate themselves until they have completed at least five days of antibiotic treatment to prevent spreading the infection, especially to susceptible infants.