Pertussis (Whooping Cough)

What is Pertussis?

Pertussis (whooping cough) is a respiratory tract infection marked by a paroxysmal cough.

• First identified in the 16th century. In 1906, Bordet isolated the most common causative organism, Bordetella pertussis.
• Vaccination cut reported cases by more than 99% from the 1930s to the 1980s.
• It remains a significant cause of morbidity and mortality in infants younger than 2 years.

Pathophysiology

Humans are the sole reservoir for B pertussis and B parapertussis.

• Bordetella pertussis, a gram-negative pleomorphic bacillus, is the main causative organism.
• It spreads via aerosolized droplets from an infected person's cough, attaching to and damaging ciliated respiratory epithelium from the nasopharynx down to the bronchi and bronchioles.
• A mucopurulent sanguineous exudate forms in the respiratory tract, compromising the small airways and predisposing to atelectasis, cough, cyanosis, and pneumonia.
• Transmission occurs through face-to-face contact, shared confined space, or contact with oral, nasal, or respiratory secretions.

Statistics and Incidences

Since the early 1980s, pertussis incidence has cycled upward, with peaks every 2-5 years.

• After dropping sharply during the COVID-19 pandemic, US cases rebounded in 2024: the CDC reported more than 35,000 cases, over six times the roughly 7,000 reported in 2023 and a return to the pre-pandemic pattern of more than 10,000 cases a year (CDC pertussis surveillance).
• Declining vaccination coverage is a driver. In the 2023 to 2024 school year, kindergarten coverage for the pertussis-containing (DTaP) vaccine fell below 93%, down from about 95% in 2019 (CDC).
• Infants younger than 1 year carry the highest risk of hospitalization and death, and pertussis deaths in the US are concentrated in this age group.
• Worldwide, pertussis remains a major cause of vaccine-preventable death in young children, with hundreds of thousands of deaths estimated each year.

Clinical Manifestations

The incubation period is 3-12 days. Pertussis runs about 6 weeks, divided into catarrhal, paroxysmal, and convalescent stages, each lasting 1-2 weeks.

• Stage 1, catarrhal phase. Nasal congestion, rhinorrhea, and sneezing, variably with low-grade fever, tearing, and conjunctival suffusion. Pertussis is most infectious during this phase but can stay communicable for 3 or more weeks after the cough starts.
• Stage 2, paroxysmal phase. Paroxysms of intense coughing lasting up to several minutes. This stage typically runs 1 to 6 weeks but can last up to 10 weeks (CDC). In older infants and toddlers, paroxysms are occasionally followed by a loud whoop; posttussive vomiting and turning red with coughing are common. Infants may not whoop at all and can instead present with apnea (pauses in breathing), the most dangerous sign in this age group.
• Stage 3, convalescent phase. Gradual recovery over roughly 2 to 3 weeks, with a chronic cough that may linger for weeks.

Assessment and Diagnostic Findings

The criterion standard for diagnosis is isolation of B pertussis in culture.

• Chest radiography. May reveal perihilar infiltrates or edema with variable atelectasis.
• Blood work. Leukocytosis with absolute lymphocytosis occurs during the late catarrhal and paroxysmal phases. In infants aged 90 days or younger, serial WBC monitoring is crucial for risk and prognosis.
• Cultures. Blood cultures are uniformly negative because B pertussis grows only in respiratory epithelium. Recovery rates are highest during the catarrhal or early paroxysmal phase and low after the fourth week of illness.
• PCR assay and ELISA. PCR and antigen detection are increasingly used: greater sensitivity, faster results, and usable later in the course. A positive PCR or culture is the case definition for reporting to the CDC or WHO, though some recommend confirming with ELISA before declaring an epidemic.

Medical Management

Supportive therapy is the mainstay in active infection.

• Hospitalization. Strongly consider it for patients at risk for severe disease and complications.
• Diet. No special diet, but maintain a clinically age-appropriate one.
• Activity. Guided by clinical course; in general, activity as tolerated.
• Monitoring. Most patients older than 1 year can be treated as outpatients if they do not meet admission criteria.

Pharmacological Management

Antimicrobials given during the catarrhal phase may ameliorate the disease.

• Antibiotics. Macrolides are first-line for treatment and post-exposure prophylaxis. Azithromycin is generally preferred, with clarithromycin and erythromycin as alternatives; azithromycin is favored in infants younger than 1 month because erythromycin is linked to infantile hypertrophic pyloric stenosis (CDC). Starting treatment in the first 1 to 2 weeks, before paroxysms begin, can lessen symptoms; given later it does little for the cough but still limits spread. Treat household and close contacts promptly to curb secondary transmission.
• Vaccines. Active immunization is the most effective prevention. DTaP is given to children younger than 7 years and Tdap to adolescents, adults, and pregnant patients (a dose in each pregnancy protects the newborn). Vaccines consist of cellular components that act as antigens to build resistance.

Nursing Management

Nursing Assessment

• Airway patency. A patent airway is always the first priority.
• Auscultation. Listen for normal or adventitious breath sounds.
• Respirations. Note quality, rate, pattern, depth, nasal flaring, dyspnea on exertion, splinting, accessory muscle use, and the position the patient takes to breathe.

Nursing Diagnosis

• Ineffective airway clearance related to copious, tenacious bronchial secretions.
• Impaired breathing pattern related to decreased airway patency.

Nursing Care Planning and Goals

• Maintain clear, open airways with normal breath sounds, normal rate and depth, and effective cough after treatments and deep breaths.
• Demonstrate increased air exchange.
• Identify methods to improve secretion removal.
• Recognize the significance of sputum changes (color, character, amount, odor).
• Identify and avoid factors that inhibit airway clearance.

Nursing Intervention

• Teach coughing and breathing. Take a deep breath, hold for 2 seconds, then cough two or three times in succession.
• Promote effective coughing. Teach optimal positioning (sitting), pillow or hand splints, use of abdominal muscles, quad and huff techniques, incentive spirometry, and the value of ambulation and frequent position changes.
• Position the patient. Upright if tolerated; check regularly to prevent sliding down in bed.
• Push fluids. Encourage oral intake up to 3 liters per day within cardiac and renal limits.
• Give medications as prescribed. Antibiotics, mucolytics, bronchodilators, and expectorants; note effectiveness and side effects.
• Chest physiotherapy. Postural drainage, percussion, and vibration as ordered.

Evaluation

Goals are met when the patient maintains clear airways with normal breath sounds and effective cough, shows increased air exchange, identifies methods to improve secretion removal, recognizes sputum changes, and avoids factors that inhibit airway clearance.

Documentation

• Individual findings: factors affecting the patient, interactions, social exchanges, specifics of behavior.
• Cultural and religious beliefs and expectations.
• Plan of care.
• Teaching plan.
• Responses to interventions, teaching, and actions performed.
• Attainment or progress toward desired outcomes.

Frequently Asked Questions

What causes whooping cough? Pertussis is a respiratory infection caused mainly by the gram-negative bacterium Bordetella pertussis. It spreads through aerosolized droplets when an infected person coughs or sneezes, and humans are the only reservoir.

What are the three stages of pertussis? The catarrhal stage (1 to 2 weeks) looks like a common cold and is the most contagious. The paroxysmal stage (1 to 6 weeks, up to 10) brings the violent coughing fits and the classic whoop. The convalescent stage (2 to 3 weeks) is gradual recovery with a lingering cough (CDC).

Why is pertussis so dangerous for infants? Babies younger than 1 year have the highest risk of severe disease, hospitalization, and death. They often do not whoop and may instead stop breathing (apnea), so close airway and breathing monitoring is critical.

What antibiotic treats whooping cough? Macrolides are first-line, with azithromycin generally preferred. It works best when started in the first 1 to 2 weeks; given later it does not shorten the cough but still reduces spread to others (CDC).

Can vaccinated people still get pertussis? Yes. Protection from DTaP and Tdap wanes over time, so vaccinated people can still catch and spread pertussis, though usually with milder illness. This is why booster doses and a Tdap dose during each pregnancy matter.

Why are whooping cough cases rising again? US cases topped 35,000 in 2024, a return to pre-pandemic levels and over six times the 2023 count, alongside a drop in kindergarten DTaP coverage to below 93% (CDC).