Pertussis nursing: three-stage progression, droplet precautions, and azithromycin use

LS
By Lindsay Smith, AGPCNP
Updated October 22, 2026

Reviewed for clinical accuracy · Methodology: NIH, NCBI, AANP guidelines

Pertussis – whooping cough – is caused by Bordetella pertussis, a gram-negative coccobacillus that remains one of the most contagious respiratory pathogens in human medicine, with a basic reproduction number (R0) often cited at 12–17 in unvaccinated populations. Despite widespread childhood vaccination with DTaP, pertussis never retreated to historical rarity. US reports fell to a few thousand a year during the COVID-19 pandemic, then rebounded to 35,435 provisional cases in 2024 and 28,783 in 2025, with 16 deaths in 2025, 10 of them in infants under 1 year (CDC provisional surveillance). The true incidence is estimated to be substantially higher because atypical presentations in vaccinated adolescents and adults are frequently misdiagnosed as bronchitis or prolonged viral upper respiratory infections. For nursing students, pertussis tests clinical recognition across its three distinct disease stages, infection control decision-making (the droplet vs. airborne distinction is a recurring NCLEX target), antibiotic pharmacology (the erythromycin-infantile pyloric stenosis association is frequently tested), and high-risk population management – particularly the life-threatening presentations in infants under 6 months, where the classic inspiratory whoop may be absent and apnea may be the only clinical sign.

This reference covers pathophysiology, the catarrhal-paroxysmal-convalescent stage sequence, nursing assessment priorities, isolation and infection control, medications, special populations, vaccination, complications, and six NCLEX-style practice questions with full rationales. Use alongside the tetanus nursing reference for comparison of other DTaP/Tdap vaccine-preventable diseases, the influenza nursing reference for droplet precaution comparison, the meningococcal meningitis nursing reference for another vaccine-preventable disease cluster, the pneumonia nursing reference for management of the most common pertussis complication, and the sepsis nursing reference for secondary infection risk.

Fast-scan summary: pertussis

Feature Key facts
Pathogen Bordetella pertussis – gram-negative coccobacillus; strictly human pathogen, no animal reservoir
Transmission Respiratory droplets from coughing and sneezing; highly contagious – secondary attack rates in households are high even when contacts are up to date on vaccination
Incubation period 7–10 days (range 4–21 days)
Stages Catarrhal (1–2 weeks) → paroxysmal (usually 1–6 weeks, up to 10) → convalescent (weeks to months); total duration often 6–10 weeks – hence "the 100-day cough"
Most infectious stage Catarrhal stage – patient looks like a simple URI but is shedding maximum organisms
Characteristic finding Inspiratory whoop following paroxysm of coughs; post-tussive vomiting; lymphocytosis on CBC
Isolation precautions Standard plus droplet precautions until 5 days of effective antibiotic therapy; some facilities add respirators for aerosol-generating procedures
First-line treatment Azithromycin (drug of choice under 1 month; a preferred macrolide at all ages); reduces contagiousness but does NOT shorten an established paroxysmal stage
Vaccine DTaP (children); Tdap booster (adolescents, adults, pregnant women 27–36 weeks); no lifelong immunity – both vaccine and natural infection provide waning protection
Most dangerous in Infants < 6 months – highest hospitalization and mortality; apnea, rather than a whoop, may be the presenting sign
Most common complication In infants under 12 months, CDC lists apnea (68%) and pneumonia (22%) as the most common complications

Pathophysiology

The organism

Bordetella pertussis is a small, gram-negative coccobacillus that is an obligate human pathogen – it has no animal reservoir, and all transmission is person to person via respiratory secretions. Unlike many gram-negative bacteria that primarily cause disease through endotoxin (lipopolysaccharide), B. pertussis is a virulence-factor-rich organism that uses a coordinated suite of adhesins and toxins to colonize the respiratory epithelium and evade host immune responses.

The two virulence factors most clinically important for nursing students are:

Filamentous hemagglutinin (FHA): The primary adhesin. FHA is a long, filamentous surface protein that binds the organism tightly to ciliated respiratory epithelial cells, particularly in the trachea and bronchi. This attachment is what initiates colonization and protects B. pertussis from mucociliary clearance. FHA also helps the organism bind to macrophages in a way that suppresses macrophage killing – a key immune evasion strategy.

Pertussis toxin (PT): The principal toxin responsible for the systemic effects of pertussis. Pertussis toxin is an ADP-ribosyltransferase that inactivates Gi-coupled signaling proteins in host cells. Two consequences are especially clinically significant:

  1. Airway epithelial damage: Tracheal cytotoxin, a fragment of the bacterial cell wall, damages and kills ciliated epithelial cells, and the organism’s toxins together impair the mucociliary escalator – the airway’s primary clearance mechanism. Mucus and debris accumulate in the airways. The exact trigger of the paroxysmal cough is still under study and appears to be toxin-mediated. Recovery of the damaged epithelium takes weeks, which is the usual explanation for why coughing persists through the convalescent stage long after bacteria are cleared.

  2. Lymphocytosis: Pertussis toxin blocks lymphocyte trafficking by inhibiting Gi-coupled chemokine receptors on lymphocytes. Lymphocytes cannot exit the bloodstream to migrate into tissues, and they cannot leave lymph nodes normally. The result is an accumulation of lymphocytes in the peripheral blood – a characteristic lymphocytosis. Because it is a direct toxin effect, a high lymphocyte count in a coughing infant should point toward pertussis rather than be dismissed as a viral picture. It is most pronounced in unvaccinated infants and young children, and is often mild or absent in adolescents, adults, and vaccinated patients.

Why the cough is paroxysmal

The inspiratory whoop of pertussis is the forceful inspiratory effort that follows a paroxysm (a rapid burst of coughs on a single exhalation). During a paroxysm, the patient expels air repeatedly until forced to inhale. The sudden inhalation through a partially obstructed, mucus-laden upper airway against the background of ciliostasis-induced secretion accumulation produces the high-pitched “whoop.” Not all patients produce an audible whoop: young infants often lack the strength to generate one and may gag, gasp, or stop breathing instead, and vaccinated adolescents and adults may have attenuated disease without the classic sound.


The three clinical stages

Pertussis progresses through three distinct stages. Stage recognition is a core NCLEX competency because nursing interventions, infection control priorities, and diagnostic yield differ by stage.

Catarrhal stage (weeks 1–2)

The catarrhal stage is clinically indistinguishable from a common cold or mild upper respiratory infection. The patient presents with:

  • Low-grade fever (often absent or minimal)
  • Coryza (runny nose)
  • Lacrimation
  • Mild cough, progressively worsening
  • No characteristic whooping at this stage

This stage represents the greatest infection control threat. B. pertussis is present at maximum density in respiratory secretions, yet the patient appears to have an ordinary cold. Household transmission and healthcare worker exposure most commonly occur here, before the diagnosis is even considered. Any patient presenting with URI symptoms who has known contact with a confirmed pertussis case, who is unvaccinated or incompletely vaccinated, or who is an infant without age-appropriate vaccination must trigger prompt isolation and consideration of empirical antibiotic treatment.

Antibiotics initiated during the catarrhal stage can abort or significantly attenuate disease progression.

Paroxysmal stage (usually 1–6 weeks, up to 10)

The paroxysmal stage is the classic phase of pertussis and the one nursing students are expected to recognize in clinical scenarios. Defining features:

Coughing paroxysms: Rapid, staccato bursts of coughs without inhalation between each one. CDC describes an average of about 15 attacks per 24 hours, often worse at night, increasing over the first 1–2 weeks and staying at that frequency for 2–3 weeks before gradually easing. Paroxysms are exhausting and can be triggered by feeding, crying, cold air, activity, or suction. Patients may appear well between episodes.

Inspiratory whoop: The characteristic high-pitched sound on forceful inhalation immediately following a paroxysm. More common in school-age children than in infants or adults. Its absence does not exclude the diagnosis.

Post-tussive vomiting: Vomiting that occurs immediately after a paroxysm (from gagging on mucus and the physical effort of coughing) is common and is an important clinical clue – especially in adults where the whoop may be absent.

Cyanosis: During severe paroxysms, particularly in infants, patients may become cyanotic from hypoxia. In young infants, apnea, sometimes with little or no cough, may be the primary presentation, occurring during or after paroxysms.

Between episodes: Patients are often afebrile and appear well between paroxysms, which can mislead clinicians into underestimating severity.

Antibiotics started during the paroxysmal stage reduce contagiousness (bacterial shedding ceases within 5 days) but do not shorten the duration of paroxysms. The cough paroxysms persist because toxin-mediated airway damage outlasts the bacteria themselves. This distinction is high-yield for NCLEX.

Convalescent stage (weeks to months)

The convalescent stage is defined by gradual improvement in cough frequency and severity. CDC describes less persistent paroxysms that disappear over 2–3 weeks, although a milder cough can linger for months. Coughing episodes may recur or worsen transiently during subsequent respiratory infections because the recovering airway remains sensitive during intercurrent illnesses.

The term “100-day cough” refers to the historical observation that symptoms can persist for approximately 100 days (roughly 14 weeks) from onset – a duration that far exceeds what most clinicians or patients expect from a respiratory infection, and that often leads to delayed diagnosis.


Nursing assessment

Vital signs and respiratory monitoring

  • Temperature: Often normal or low-grade, especially in vaccinated patients. High fever should prompt evaluation for secondary bacterial pneumonia.
  • Respiratory rate: Monitor closely before, during, and after paroxysms. Sustained tachypnea between paroxysms suggests developing pneumonia or hypoxemia.
  • Oxygen saturation: Continuous pulse oximetry in hospitalized patients, particularly infants. Desaturation during paroxysms is expected; persistent hypoxemia between episodes is a warning sign.
  • Heart rate: Bradycardia during paroxysms in infants is an ominous sign associated with hypoxic cardiovascular compromise.

Respiratory assessment priorities

  • Character and frequency of coughing episodes – document paroxysm duration, post-tussive vomiting, presence/absence of whoop
  • Work of breathing between paroxysms – retractions, nasal flaring, accessory muscle use
  • Breath sounds – decreased aeration or new crackles suggest developing pneumonia
  • Mucus color and quantity – thick, ropy secretions typical; purulent sputum suggests secondary infection
  • Cyanosis – perioral cyanosis or central cyanosis during paroxysms requires immediate intervention

Laboratory findings

CBC with differential: The hallmark laboratory finding in pertussis is leukocytosis with lymphocytosis, especially in young, unvaccinated children:

  • The lymphocytosis is a direct effect of pertussis toxin, so it should not be written off as a co-existing viral illness
  • A normal count does not exclude pertussis, particularly in adolescents, adults, and vaccinated patients
  • In young infants, a rapidly rising white count is a severity marker: in a Southern California PICU series, infants who died or developed pulmonary hypertension exceeded a WBC of 30,000/μL, a heart rate of 170, and a respiratory rate of 70 sooner after cough onset than other infants (Murray 2013)
  • An unexplained lymphocytosis in a patient with paroxysmal cough should raise strong clinical suspicion for pertussis

Nasopharyngeal culture or PCR: PCR from a nasopharyngeal swab or aspirate is the most widely used test and performs best in the first 3 weeks of cough. Culture is the traditional gold standard and is highly specific, but it needs special media, is less sensitive, and takes up to a week or more. Serology (anti-PT IgG) is useful later in the illness when PCR yield declines.

Infant vs. adult presentation differences

Feature Infants (< 6 months) Older children and adults
Whoop Often absent – may gag, gasp, or become apneic instead Present in classic cases; may be absent in vaccinated adults
Apnea Common, may be primary presentation Rare
Post-tussive vomiting Common Common, and a useful clue when there is no whoop
Cyanosis Common during paroxysms Less common; occurs in severe episodes
Hospitalization About a third of infants under 12 months need hospital care (CDC); 41% of reported cases under 6 months were hospitalized in 2025 Usually outpatient if no complications
Mortality risk Highest – about 90% of US pertussis deaths occur in young infants (Paddock 2008) Low in otherwise healthy adults
Lymphocytosis Can be extreme; a WBC above 30,000/μL soon after cough onset marks infants at risk of pulmonary hypertension and death Present but typically less pronounced

High-risk groups

  • Infants under 6 months: Too young to have completed primary DTaP series; highest mortality group
  • Unvaccinated or incompletely vaccinated individuals of any age
  • Vaccinated adolescents and adults with waning immunity: Pertussis immunity from both natural infection and vaccination is not lifelong; protection wanes significantly within 4–12 years
  • Immunocompromised patients: May have prolonged shedding and atypical presentations
  • Pregnant women: Severe coughing is distressing and can transmit infection to the newborn at delivery; Tdap in pregnancy protects the newborn through passive antibody transfer before the infant can receive their own primary series

Nursing interventions

Airway management

Airway management is the central nursing priority in pertussis, particularly for hospitalized infants and young children.

Cluster care: Paroxysms are triggered by stimulation. Cluster all nursing interventions – vital signs, medication administration, repositioning, feeding – to minimize the number of times the patient is disturbed. Each unnecessary interruption risks triggering a coughing episode.

Suction equipment at bedside: Thick mucus secretions combined with post-tussive vomiting create aspiration risk. Have suction equipment set up and immediately accessible. Suction only as needed – excessive suctioning triggers additional paroxysms.

Positioning: Elevate the head of the bed. For infants, positioning in a semi-upright or lateral position during and after feedings reduces aspiration risk from post-tussive vomiting.

Oxygen therapy: Administer supplemental oxygen as needed to maintain the ordered target saturation (follow neonatal parameters for premature infants). High-flow nasal cannula or non-rebreather mask may be required during severe paroxysms. Be prepared for rapid desaturation.

Resuscitation readiness: For infants, have resuscitation equipment immediately accessible at the bedside. Bradycardia and apnea can be sudden. Brief stimulation (tactile) is often sufficient to restart breathing in mild apnea episodes; have bag-valve-mask available for events that do not self-terminate.

Infection control

Pertussis is highly contagious. Implement precautions immediately on clinical suspicion – do not wait for laboratory confirmation.

Droplet precautions: CDC isolation guidance assigns pertussis to standard plus droplet precautions. This requires:

  • Surgical mask for healthcare workers on entering the patient’s room
  • Private room or cohorting with other confirmed pertussis patients
  • Gloves and gown under standard precautions whenever contact with respiratory secretions or vomit is anticipated

Aerosol-generating procedures: CDC’s isolation Appendix A lists no airborne upgrade for pertussis, and CDC’s 2024 pertussis guidance for healthcare personnel does not mention respirators or aerosol-generating procedures. If your facility adds an N95 during suctioning or bronchoscopy, that is a local policy layered on top of the CDC Droplet baseline.

Discontinuation criteria: Droplet precautions continue until 5 days of effective antibiotic therapy have been completed. CDC Appendix A gives no endpoint for untreated patients. CDC’s 2024 healthcare personnel guidance describes communicability as lasting up to 3 weeks after the onset of paroxysms, and it uses 21 days from cough onset for excluding symptomatic staff who do not take antibiotics. Follow your infection prevention team.

Contact tracing and chemoprophylaxis: CDC supports post-exposure prophylaxis for all asymptomatic household contacts within 21 days of cough onset in the index patient, and for people at high risk of severe pertussis (such as young infants and women in the third trimester) and their close contacts. Vaccination status does not change this, because secondary attack rates are high even among vaccinated household contacts.

Nutrition and hydration management

Post-tussive vomiting combined with anorexia from the exhaustion of repeated paroxysms creates significant nutritional and hydration risk.

  • Offer small, frequent, high-calorie feedings; avoid large-volume meals that fill the stomach and worsen vomiting
  • Time feedings for immediately after a paroxysm, when the next episode is least likely
  • In infants with significant vomiting or poor oral intake, IV fluids or nasogastric feeding may be required to maintain hydration and caloric goals
  • Monitor weight daily in hospitalized infants
  • Document intake and output carefully; dehydration is a complication that compounds respiratory compromise

Monitoring for complications

  • Vital signs and oxygen saturation every 2–4 hours minimum; continuous pulse oximetry for infants
  • Respiratory assessment before and after each paroxysm
  • Neuro checks in infants for signs of encephalopathy (altered consciousness, seizures)
  • Report new fever, purulent sputum, or worsening respiratory status immediately – these suggest secondary pneumonia
  • Daily weight in pediatric and infant patients

Medications

Medication Class / mechanism Use Key nursing considerations
Azithromycin Macrolide antibiotic; inhibits 50S ribosomal subunit, blocking bacterial protein synthesis Drug of choice for infants < 1 month and a preferred macrolide at all ages; 5-day course Preferred macrolide in pregnancy; IHPS has also been reported after azithromycin in young infants, so monitor infants < 1 month for projectile vomiting; QT prolongation risk – monitor ECG in high-risk patients; better tolerated than erythromycin; does not shorten an established paroxysmal stage
Clarithromycin Macrolide antibiotic Alternative to azithromycin; recommended only for infants ≥ 1 month; 7-day course Generally avoided in pregnancy; drug interactions via CYP3A4; GI side effects common; refrigerate oral suspension
Erythromycin Macrolide antibiotic (older agent) Historical first-line; now rarely used due to inferior tolerability Not preferred for infants < 1 month: early-life exposure is associated with infantile hypertrophic pyloric stenosis (IHPS), with a nearly 8-fold risk after exposure in days 3–13 of life in one cohort (Cooper 2002). This is a high-yield NCLEX association. 14-day course; GI side effects common in all age groups.
TMP-SMX (trimethoprim-sulfamethoxazole) Antifolate combination; inhibits sequential steps in folate synthesis Alternative for patients ≥ 2 months who cannot take macrolides or when macrolide resistance is suspected Not recommended in pregnancy or while nursing an infant; contraindicated in infants < 2 months (risk of kernicterus); monitor CBC for hematologic effects; adequate hydration to prevent crystalluria
Supplemental oxygen Supportive care Hypoxemia during or between paroxysms Titrate to the ordered SpO2 target (follow neonatal protocol for premature infants); CDC lists Droplet only; some facilities add an N95 for high-flow devices as local policy
IV fluids Supportive care Dehydration secondary to post-tussive vomiting and poor oral intake Isotonic fluid typically; monitor for fluid overload in infants with pulmonary compromise; assess urine output every shift

See the medication rights nursing reference for antibiotic administration safety practices.

Critical pharmacology point: Antibiotics in pertussis serve primarily to reduce transmission (by eliminating B. pertussis from respiratory secretions) and, if given in the catarrhal stage, to attenuate disease. They do not reverse the toxin-mediated ciliostasis that causes paroxysmal coughing. Once the paroxysmal stage is established, patients will continue coughing for weeks regardless of antibiotic treatment. Explain this clearly to patients and families so they understand the cough will continue and do not request repeated antibiotic courses. CDC advises treating within 3 weeks of cough onset for people aged 1 year and older, and within 6 weeks for infants under 1 year and pregnant women near term.


Special populations

Infants under 6 months

Infants younger than 6 months carry the highest burden of pertussis mortality and severe morbidity in the United States. Several factors compound their vulnerability:

  • No completed primary series: The DTaP schedule begins at 2 months; infants younger than this are completely unprotected by vaccine, and even infants who have received one or two doses have not achieved full immunity.
  • Atypical presentation: The classic whoop is usually absent. Apnea – episodes of cessation of breathing, sometimes without coughing at all – may be the initial or dominant presentation. Infants can be brought in for “breathing problems” or brief resolved unexplained events (BRUEs) before pertussis is considered.
  • Extreme lymphocytosis: Counts above 50,000 cells/μL occur in severe infant pertussis and are associated with leukostasis, pulmonary hypertension, and cardiovascular collapse. Exchange transfusion or leukoreduction has been used in extreme cases, though evidence for mortality benefit is limited.
  • ICU admission: A subset of hospitalized infants need intensive care. In US discharge data from 1993–2004, 86% of infant pertussis hospitalizations were in infants 3 months or younger, as were 95% of those ventilated and every infant who died (Cortese 2008).

For nursing students, the key takeaway is that any infant with paroxysmal cough, apnea, or post-tussive vomiting, especially with a coughing household contact, should be considered for pertussis until proven otherwise. Household members, most often mothers, are a common identified source (Bisgard 2004).

Pregnancy

  • A mother with pertussis around delivery can pass the infection to her newborn, which is why CDC extends the treatment window to 6 weeks of cough for women in the third trimester.
  • Azithromycin is the preferred antibiotic in pregnancy.
  • Tdap vaccination at 27–36 weeks of every pregnancy has been recommended by ACIP (Advisory Committee on Immunization Practices) since 2012, regardless of prior Tdap vaccination history (MMWR 2013). This timing maximizes transplacental antibody transfer to the infant, providing passive protection during the first weeks of life before the primary DTaP series can begin.

Adults with waning immunity

Adolescents and adults who received childhood DTaP, or who had a previous natural infection, are not permanently protected. Vaccine-derived immunity declines significantly over 4–12 years. Adults who develop pertussis typically present with a prolonged cough illness lasting weeks, often without the dramatic whoop, leading to misdiagnosis as bronchitis, post-nasal drip, or atypical pneumonia. Adults are often the source of transmission to unvaccinated or incompletely vaccinated infants in the household.


Vaccination

Primary series (children): DTaP

DTaP (diphtheria, tetanus, acellular pertussis) is an inactivated combination vaccine containing acellular pertussis antigens – including detoxified pertussis toxin and filamentous hemagglutinin – rather than whole killed organisms (as in the older DTP vaccine). The acellular formulation has substantially fewer systemic side effects than whole-cell DTP while maintaining good immunogenicity.

The recommended primary series schedule:

  • 2 months
  • 4 months
  • 6 months
  • 15–18 months
  • 4–6 years

The first three doses form the primary series, and the 15–18 month and 4–6 year doses are boosters; all five are needed to complete the childhood schedule. Children who miss doses should have vaccination resumed without restarting the series.

See the tetanus nursing reference for complementary detail on the diphtheria and tetanus components of this combined vaccine.

Tdap booster (adolescents and adults)

Tdap (tetanus, reduced-dose diphtheria, acellular pertussis) is the adult/adolescent formulation. It contains lower antigen doses than DTaP. The lower pertussis antigen dose is deliberate – higher doses cause unacceptably high rates of local reactions in older individuals who have had prior antigen exposure.

  • One dose of Tdap recommended at 11–12 years for adolescents
  • Adults who have never received Tdap should receive one dose, then Td or Tdap every 10 years (ACIP 2019 update, Havers 2020)
  • Pregnant women: one Tdap dose at 27–36 weeks of every pregnancy, regardless of prior Tdap or Td history
  • Healthcare workers: Tdap recommended if not previously received; critical for workers in neonatal and pediatric units (cocoon strategy)

The cocoon strategy

The cocoon strategy refers to vaccinating all close contacts of a newborn infant – parents, siblings, grandparents, household members, and regular caregivers – with Tdap before or immediately after the infant’s birth. The goal is to surround (“cocoon”) the infant with immune individuals during the window of maximum vulnerability before the primary DTaP series is completed. Healthcare workers in neonatal units are considered part of this strategy.

Limitations of the cocoon strategy: it requires vaccinating multiple individuals, compliance is imperfect, and protection is indirect. Maternal Tdap in pregnancy (described above) provides more reliable passive protection to the infant through transplacental IgG transfer and is now the main strategy.


Isolation and infection control

Precaution type

The CDC recommends droplet precautions as the standard isolation category for pertussis. Key elements:

  • Private room preferred; cohorting with other confirmed pertussis patients is acceptable
  • Healthcare workers wear a surgical mask on entering the room
  • Use gloves and gown under standard precautions when contact with secretions is likely

CDC Appendix A assigns Droplet + Standard for pertussis until 5 days after effective antibiotic therapy begins and lists no airborne upgrade for aerosol-generating procedures. NCLEX questions follow this CDC standard; any extra respiratory protection a facility adds during procedures is local policy.

Isolation discontinuation

A patient with pertussis may be removed from isolation when either of the following criteria is met:

  • 5 days after effective antibiotic therapy has begun (macrolides clear the organism from the nasopharynx within about 5 days)
  • If antibiotics were not given, after the infectious period has passed. CDC describes communicability as lasting up to 3 weeks after paroxysm onset (CDC uses 21 days from cough onset for excluding symptomatic staff); confirm with infection prevention

Reporting requirements

Pertussis is a nationally notifiable disease. Confirmed and probable cases must be reported to the local or state health department, which will initiate contact tracing and coordinate post-exposure prophylaxis for close contacts.


Complications

Complication Mechanism Notes
Pneumonia B. pertussis pneumonia itself or secondary bacterial pneumonia; impaired mucociliary clearance allows infection to descend into the lower airways Occurs in 22% of infants under 12 months with pertussis (CDC); fatal infant cases show necrotizing bronchiolitis and pneumonia (Paddock 2008); see pneumonia nursing reference
Apnea Cough-induced hypoxia or post-paroxysmal airway fatigue; central or obstructive in infants The most common complication in infants under 12 months (68%, CDC); a key reason young infants are admitted and monitored
Encephalopathy Hypoxia from prolonged apnea or cyanotic episodes; possible direct effect of pertussis toxin on CNS Manifests as seizures, altered consciousness; rare but associated with high morbidity
Pulmonary hypertension Leukocyte aggregates in small pulmonary vessels plus hypoxic pulmonary vasoconstriction, creating a cycle of refractory pulmonary hypertension (Paddock 2008) Occurs in infants with extreme lymphocytosis; associated with high mortality
Rib fractures Mechanical force of violent coughing paroxysms in adults More common in adults with osteoporosis; presents as pleuritic chest pain worsening with cough
Subconjunctival hemorrhage Markedly elevated intrathoracic pressure during cough paroxysm ruptures conjunctival blood vessels Painless; bilateral or unilateral; resolves without treatment; also seen with severe vomiting
Urinary incontinence Repeated coughing paroxysms overwhelm urinary sphincter control Common in adult women with multiparity or pre-existing stress incontinence; rarely discussed but significant quality-of-life impact
Weight loss / failure to thrive Post-tussive vomiting and anorexia reduce caloric intake over weeks Monitor weight in infants; NG feeding may be required

NCLEX practice questions

Question 1

A nurse is caring for a 2-month-old infant admitted with a 10-day history of cough episodes followed by brief apnea. The mother reports the infant becomes blue during coughing episodes and vomits afterward. Which isolation precaution should the nurse initiate immediately?

A. Standard precautions only B. Airborne precautions C. Droplet precautions D. Neutropenic precautions

Reveal answer and rationale

Correct answer: C – Droplet precautions

B. pertussis is transmitted primarily via respiratory droplets (large particles that travel a short distance). CDC recommends standard plus droplet precautions for pertussis. This includes a surgical mask for healthcare workers on entering the room, and a private room where available. Airborne precautions (N95, negative-pressure room) are required for diseases transmitted by airborne particles – such as tuberculosis, measles, and varicella – and are not the standard for pertussis (CDC lists no airborne upgrade for pertussis, though some facilities add an N95 for aerosol-generating procedures as local policy). Standard precautions alone are insufficient. Neutropenic precautions protect the patient from external infection and are irrelevant here.


Question 2

A nurse is reviewing the complete blood count (CBC) of a patient with a 3-week history of severe paroxysmal cough. The results show: WBC 38,000 cells/μL with 75% lymphocytes. Which interpretation is most accurate?

A. This finding is inconsistent with pertussis and suggests a concurrent viral infection B. This marked lymphocytosis is a characteristic finding in pertussis caused by pertussis toxin blocking lymphocyte trafficking C. The patient likely has leukemia, which should be the primary diagnosis D. This is a normal finding in a patient with any respiratory infection

Reveal answer and rationale

Correct answer: B – This marked lymphocytosis is a characteristic finding in pertussis caused by pertussis toxin blocking lymphocyte trafficking

Pertussis toxin inhibits Gi-coupled chemokine receptors on lymphocytes, preventing them from exiting the bloodstream and lymph nodes into peripheral tissues. This causes an accumulation of lymphocytes in the peripheral blood. A WBC of 38,000 with lymphocyte predominance in the context of paroxysmal cough is a classic pertussis finding, and pertussis toxin explains it better than viral co-infection or a hematologic malignancy. While leukemia can cause marked lymphocytosis, the clinical context (paroxysmal cough, duration of illness) makes pertussis the priority diagnosis. This finding supports the diagnosis and should prompt nasopharyngeal PCR confirmation.


Question 3

A nurse is preparing to administer antibiotics to a 3-week-old infant diagnosed with pertussis. Which antibiotic order requires the nurse to immediately clarify with the prescriber before administration?

A. Azithromycin oral suspension B. Erythromycin ethylsuccinate C. Clarithromycin oral suspension D. TMP-SMX oral suspension

Reveal answer and rationale

Correct answer: B – Erythromycin ethylsuccinate

Erythromycin given in the first weeks of life is associated with infantile hypertrophic pyloric stenosis (IHPS). IHPS is a life-threatening condition involving hypertrophy of the pyloric muscle, causing gastric outlet obstruction that presents with forceful (projectile) vomiting and can lead to severe dehydration, metabolic alkalosis, and death if untreated. CDC names azithromycin the drug of choice for infants under 1 month, while still advising monitoring because IHPS has also been reported with azithromycin. Clarithromycin is not recommended under 1 month, and TMP-SMX is contraindicated under 2 months because of kernicterus risk, but the classic NCLEX association, and the order to question first, is erythromycin in a neonate. For a 3-week-old infant, azithromycin is the correct choice.


Question 4

A parent asks the nurse why their child who completed the DTaP series at age 6 was still diagnosed with pertussis at age 16. Which response is most accurate?

A. “The DTaP vaccine provides only 30% protection – most vaccinated children still get whooping cough.” B. “Your child likely received a counterfeit vaccine. The real DTaP would have provided complete lifelong protection.” C. “Immunity from both the DTaP vaccine and natural infection wanes over time. Protection typically declines significantly within 4–12 years, which is why a Tdap booster is recommended at age 11–12.” D. “Your child’s immune system did not respond to the vaccine – this is a known failure in approximately half of all recipients.”

Reveal answer and rationale

Correct answer: C – Immunity from both the DTaP vaccine and natural infection wanes over time

A key clinical fact about pertussis immunity is that it wanes, whether derived from vaccination or natural infection. DTaP-induced immunity wanes substantially over 4–12 years, explaining why vaccinated adolescents and adults are susceptible. This is why ACIP recommends a Tdap booster at age 11–12, with additional doses for adults (especially pregnant women and healthcare workers). The vaccine is effective when immunity is active – option A significantly understates its early efficacy. Options B and D contain clinical inaccuracies. The waning immunity phenomenon is the public health explanation for why pertussis cycles persist despite high childhood vaccination rates.


Question 5

A nurse caring for a hospitalized child in the paroxysmal stage of pertussis is developing a care plan. Which intervention is the highest priority?

A. Schedule all nursing care activities together to minimize patient stimulation between paroxysms B. Perform hourly suctioning to remove secretions and prevent airway obstruction C. Place the child in Trendelenburg position to facilitate postural drainage D. Encourage aggressive oral hydration during paroxysms to replace losses from vomiting

Reveal answer and rationale

Correct answer: A – Schedule all nursing care activities together to minimize patient stimulation between paroxysms

Clustering care is the key nursing strategy in the paroxysmal stage. Pertussis paroxysms are triggered by external stimulation – handling, suctioning, feeding, procedures, or crying. By grouping all necessary interventions and minimizing disturbance between clusters, the nurse reduces the frequency of triggered paroxysms. Hourly suctioning (option B) would itself be a repeated trigger – suction only as needed. Trendelenburg positioning (option C) increases risk during coughing paroxysms and is not recommended. Oral hydration during paroxysms (option D) dramatically increases aspiration risk – feedings should be timed for immediately after a paroxysm, not during one.


Question 6

A nurse is assessing a 6-week-old infant admitted for evaluation of “breathing pauses.” The parent reports a mild runny nose for one week, followed by episodes where the infant stops breathing for 15–30 seconds. The infant has not received any vaccinations. Which assessment finding best supports a diagnosis of pertussis?

A. Temperature of 39.8°C (103.6°F) B. WBC 52,000 cells/μL with lymphocyte predominance on differential C. Prominent inspiratory whoop on auscultation during coughing D. Purulent nasal discharge

Reveal answer and rationale

Correct answer: B – WBC 52,000 cells/μL with lymphocyte predominance on differential

In infants under 6 months, the classic inspiratory whoop (option C) is typically absent because infants cannot generate sufficient airway pressure to produce the sound – making it an unreliable diagnostic sign in this age group. High fever (option A) is atypical in pertussis; the catarrhal stage is characterized by low-grade or absent fever. Purulent discharge (option D) points toward a secondary bacterial infection rather than classic pertussis. Marked lymphocytosis is the characteristic laboratory finding of B. pertussis infection – caused by pertussis toxin blocking lymphocyte trafficking – and a count this high in a young infant is also a warning sign of severe disease. In the context of apnea episodes, catarrhal prodrome, and absent vaccination history, strongly supports the diagnosis. Nasopharyngeal PCR should be sent immediately.


This reference was written by Lindsay Smith, AGPCNP. Clinical information is sourced from CDC Pertussis guidelines, ACIP vaccine recommendations, and peer-reviewed literature on Bordetella pertussis pathophysiology and clinical management. For complete antibiotic dosing, consult current institutional formulary guidelines.

References

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