Pertussis Signs and Symptoms
Pertussis presents with three distinct clinical stages: an initial catarrhal stage with cold-like symptoms, followed by a paroxysmal stage with severe coughing fits (often with inspiratory "whoop" and posttussive vomiting), and finally a prolonged convalescent stage lasting weeks to months. 1
Incubation Period
- Averages 7-10 days (range: 5-21 days)
- Can be as long as 6 weeks 1
Clinical Stages
1. Catarrhal Stage (1-2 weeks)
The disease begins insidiously with symptoms indistinguishable from a common cold 1:
- Nasal congestion and runny nose
- Mild sore throat
- Mild dry cough (initially intermittent)
- Minimal or no fever (important distinguishing feature)
- Conjunctivitis, rhinorrhea, malaise 2
Critical caveat: Infants may present atypically with apneic spells and minimal cough or other respiratory symptoms 1. This is the most infectious period 1.
2. Paroxysmal Stage (2-6 weeks)
The cough becomes severe and characteristic 1:
Classic paroxysm features:
- Succession of coughs following each other without inspiration
- Terminates with inspiratory "whoop" (high-pitched sound when gasping for breath)
- Followed by posttussive vomiting
- Patient appears relatively well between episodes
- Paroxysms increase in frequency and severity as illness progresses
- More frequent at night
Age-specific variations:
- Children <2 years: Vomiting or apnea more common than whooping 2
- Adolescents and adults: Illness often milder; characteristic whoop frequently absent in previously vaccinated individuals 1, 3
- Adults: May only experience protracted cough, shortness of breath, tingling sensation in throat 2
3. Convalescent Stage (2-6 weeks or longer)
- Gradual waning of illness severity
- Paroxysms subside
- Frequency of coughing decreases
- Nonparoxysmal cough can continue for 2-6 weeks or longer
- Superimposed viral respiratory infections can trigger recurrence of paroxysms 1
Associated Symptoms and Complications
Common systemic effects 1:
- Substantial weight loss
- Sleep disturbance
- Exhaustion after coughing episodes
Complications from severe coughing pressure 1, 3:
- Pneumothorax
- Epistaxis (nosebleeds)
- Subconjunctival hemorrhage
- Subdural hematoma
- Hernia (inguinal)
- Rectal prolapse
- Urinary incontinence (especially in women)
- Rib fracture
- Herniated lumbar disc
- Cough syncope (loss of consciousness)
Infectious complications 1:
- Primary or secondary bacterial pneumonia
- Otitis media
Neurologic complications (infrequent) 1:
- Seizures
- Hypoxic encephalopathy
Diagnostic Clinical Features
For adults with acute/subacute cough 4, 5:
- Rule IN pertussis: Presence of whooping OR posttussive vomiting (high specificity: 77-80%)
- Rule OUT pertussis: Absence of paroxysmal cough OR presence of fever (high sensitivity: 93% and 82% respectively)
For children with acute cough 4:
- Assess specifically for: paroxysmal cough, posttussive vomiting, inspiratory whooping
- Posttussive vomiting is moderately suggestive (60% sensitive, 66% specific) 5
High-Risk Populations
Unvaccinated or incompletely vaccinated infants <12 months have the highest risk for:
- Severe complications
- Life-threatening disease
- Death 1
Important pitfall: Despite infants having the highest incidence, adolescents and adults account for the majority of reported cases and serve as the reservoir for transmission to vulnerable infants 1. The disease is often unrecognized in these age groups because symptoms may be atypical and the diagnosis is not considered 1, 2.