Clinical Features

Tips

Once you diagnose pertussis in a household, consider pertussis in coughing close contacts.
In the youngest infants, atypical presentation is common. The cough may be minimal or absent and the primary symptom can be apnea.
Remember, infants are at risk for severe or fatal pertussis. When you suspect a case in an older child, adolescent, or adult, inquire about contact with infants and pregnant women and consider prophylaxis.

There are three stages to clinical course of pertussis:

Catarrhal
Paroxysmal
Convalescent

Pertussis symptoms usually develop within 5 to 10 days after exposure, but sometimes not for as long as 3 weeks. Pertussis has an insidious onset with catarrhal symptoms that are indistinguishable from those of minor respiratory tract infections. The cough, which is initially intermittent, becomes paroxysmal. In typical cases paroxysms terminate with inspiratory whoop and posttussive vomiting can follow.

Paroxysms of cough, which may occur more at night, usually increase in frequency and severity as the illness progresses. The cough typically persists for 1 to 6 weeks or more. The illness can be milder and the characteristic “whoop” absent in children, adolescents, and adults who were previously vaccinated. After paroxysms subside, a nonparoxysmal cough can continue for 2 to 6 weeks or longer.

Unvaccinated or incompletely vaccinated infants younger than 12 months of age have the highest risk for severe complications and death. In infants, the cough may be minimal or absent, and apnea may be the only symptom. Despite increasing awareness and recognition of pertussis as a disease that affects adolescents and adults, clinicians often overlook pertussis in the differential diagnosis of cough illness in this population. Illness is generally less severe, and the typical “whoop” less frequently seen in adolescents and adults. It is important to educate parents to consider pertussis when their child has a cough. Let them know that it can be a severe illness, especially for infants, and they should seek immediate treatment.

Three stages to clinical course of pertussis, length, and clinical features
Stage	Length	Clinical Features
Stage 1: Catarrhal	Usually 7-10 days; range of 4-21	Characterized by: Coryza Low-grade fever Mild, occasional cough (which gradually becomes more severe)
Stage 2: Paroxysmal	Usually lasts 1-6 weeks, but may persist for up to 10 weeks	Characterized by: Paroxysms of numerous, rapid coughs due to difficulty expelling thick mucus from the tracheobronchial tree Long inspiratory effort accompanied by a high-pitched “whoop” at the end of the paroxysms Cyanosis Vomiting and exhaustion Paroxysmal attacks: Occur frequently at night, with an average of 15 attacks per 24 hours Increase in frequency during the first 1-2 weeks, remain at the same frequency for 2-3 weeks, and then gradually decrease
Stage 3: Convalescent	Usually 7-10 days; range of 4-21	Characterized by: Gradual recovery Less persistent, paroxysmal coughs that disappear in 2-3 weeks Paroxysms often recur with subsequent respiratory infections for many months after the onset of pertussis.