What are the signs and symptoms of pertussis (whooping cough)?

Signs and Symptoms of Pertussis (Whooping Cough)

Pertussis presents with characteristic paroxysmal coughing, post-tussive vomiting, and inspiratory whooping sound, with the absence of fever being a key distinguishing feature in adults. 1

Classic Presentation of Pertussis

Pertussis infection typically progresses through three distinct phases:

1. Catarrhal Phase (1-2 weeks)

• Initial virus-like illness with nonspecific symptoms 1:
  • Nasal congestion/rhinorrhea
  • Mild sore throat
  • Mild dry cough
  • Minimal or no fever
  • Conjunctivitis
  • Malaise

2. Paroxysmal Phase (2-6 weeks)

• Characterized by worsening cough that becomes paroxysmal 1:
  • Succession of coughs without intervening inspiration
  • Paroxysms terminate with inspiratory "whoop" (high-pitched sound when gasping for breath)
  • Post-tussive vomiting (vomiting induced by coughing)
  • Coughing episodes more frequent at night
  • Exhaustion after coughing episodes
  • Patient appears relatively well between episodes

3. Convalescent Phase (weeks to months)

• Gradual recovery 1:
  • Decreasing frequency of coughing bouts
  • Non-paroxysmal cough may continue for 2-6 weeks or longer
  • Viral respiratory infections may trigger recurrence of paroxysms

Key Diagnostic Features

In Adults

• Most reliable indicators for ruling in pertussis 1:

  • Inspiratory whooping (sensitivity 29.8%, specificity 79.5%)
  • Post-tussive vomiting (sensitivity 32.5%, specificity 77.7%)

• Most reliable indicators for ruling out pertussis 1:

  • Absence of paroxysmal cough (high sensitivity 93.2%)
  • Presence of fever (pertussis typically occurs without fever)

In Children

• Most reliable indicators 1:

  • Post-tussive vomiting (sensitivity 60.0%, specificity 66.0%)
  • Paroxysmal cough
  • Inspiratory whooping

• In infants <2 years 1:

  • Vomiting or apnea more commonly seen than typical whooping
  • May initially present with apneic spells and minimal cough

Complications of Pertussis

Infants and Young Children

• Higher risk for severe complications 1, 2:
  • Apnea
  • Pneumonia
  • Seizures
  • Death (highest case-fatality ratio in neonates)

All Age Groups

• Complications from severe coughing 1:
  • Pneumothorax
  • Epistaxis (nosebleeds)
  • Subconjunctival hemorrhage
  • Subdural hematoma
  • Hernia
  • Rectal prolapse
  • Urinary incontinence
  • Rib fracture
  • Weight loss
  • Sleep disturbance

Atypical Presentations

• Milder disease in previously vaccinated individuals 1
• Whooping sound may be absent in children, adolescents, and adults with previous vaccination 1
• Adults and adolescents may present with prolonged cough as the only symptom 1
• Some infected individuals may be asymptomatic 1

Clinical Pearls

1. Pertussis should be considered in patients with cough lasting >2 weeks without another apparent cause, especially if accompanied by paroxysms, post-tussive vomiting, or inspiratory whooping 1

2. The incubation period averages 7-10 days (range: 5-21 days) and has been reported to be as long as 6 weeks 1

3. Patients are most infectious during the catarrhal stage and the first 3 weeks after cough onset 1

4. In adults with acute (<3 weeks) or subacute (3-8 weeks) cough, the presence of whooping or post-tussive vomiting should prompt consideration of pertussis, while the presence of fever makes pertussis less likely 1

5. Laboratory confirmation through culture or PCR testing of nasopharyngeal specimens is recommended, especially early in the course of illness 3

6. Prompt recognition and treatment is critical, particularly for infants who have the highest risk of severe complications and death 3

AI: I've provided a comprehensive overview of pertussis signs and symptoms, organized by disease phases and highlighting the key diagnostic features for both adults and children. I've emphasized the most reliable clinical indicators based on the most recent CHEST guidelines (2019).