Is pertussis (whooping cough) common in adults?

Whooping Cough (Pertussis) in Adults

Pertussis is increasingly common in adults, with studies showing between 3.3-8% of adults experiencing pertussis infections annually, and approximately 20% of adults with persistent cough having pertussis. 1

Epidemiology and Prevalence

• Since the early 1980s, despite widespread childhood vaccination, there has been a significant increase in pertussis incidence across all age groups, with a particularly notable increase in adolescents and adults 1
• The increase in adult cases occurs because:
  • Immunity from childhood vaccination wanes approximately 5-10 years after completion 1
  • The number of adults with natural immunity from the pre-vaccine era is progressively decreasing 1
• Adults have become a major reservoir for Bordetella pertussis and are frequently the source of infection for vulnerable infants 1
• Clinical and serologic surveys of elderly individuals living independently have shown that between 3.3% and 8% have pertussis infections each year, with only 37.5-50% of these individuals developing symptoms 1
• In a Canadian multicenter prospective study, pertussis infection was confirmed in 19.9% of adolescents and adults who met criteria for post-infectious cough 1

Clinical Presentation in Adults

• Unlike in children, adult pertussis often presents atypically:

  • The classic "whoop" sound is usually absent in adults 1, 2
  • Many adults present with only a nondistinct protracted cough as the sole manifestation 1
  • Cough is typically dry and paroxysmal rather than productive 2
  • Post-tussive emesis is common 1
  • Cough tends to be spasmodic, occurring more frequently at night and after exposure to cold air 1
  • Symptoms are typically more severe in females and non-immunized individuals 1

• Duration of illness:

  • Cough usually lasts 4-6 weeks but can persist much longer during the convalescent phase 1
  • Pertussis has been nicknamed the "hundred day cough" due to prolonged coughing episodes 1

Complications in Adults

• Adults with pertussis can experience significant complications:

  • Pneumonia (up to 5% of cases) 1
  • Rib fractures from paroxysmal coughing (up to 4%) 1, 2
  • Loss of consciousness/cough syncope (up to 6%) 1, 2
  • Urinary incontinence (common in women) 1
  • Other reported complications include pneumothorax, hernias, subconjunctival hemorrhage, and severe weight loss 1
  • Hospitalization occurs in up to 3% of adults (12% in older adults) 1

• Impact on daily life:

  • 78% of employed adults with pertussis miss work (mean 9.8 days) 1
  • Adults with pertussis often make multiple healthcare visits (mean 2.5-3.7 visits) during their illness 1

Diagnosis

• Pertussis is often overlooked in the differential diagnosis of chronic cough in adults 1
• Diagnostic methods include:
  • Culture of nasopharyngeal secretions (sensitivity 25-50%) 1
  • PCR testing (sensitivity 80-100%) 1
  • Serologic testing (most accepted: significant increase in IgG serum antibody against pertussis toxin) 1

Prevention

• Vaccination remains the cornerstone of prevention 2
• The Advisory Committee on Immunization Practices (ACIP) recommends:
  • Adults aged 19-64 years should receive a single dose of Tdap to replace tetanus and diphtheria toxoids vaccine (Td) for booster immunization 1
  • Adults who have or anticipate close contact with infants aged <12 months should receive Tdap to reduce transmission risk 1
  • Healthcare personnel with direct patient contact should receive a single dose of Tdap 1

Clinical Implications

• Pertussis should be considered in the differential diagnosis for adults with prolonged cough illness
• Early recognition during the catarrhal phase is crucial for effective antibiotic treatment, which primarily prevents transmission rather than alleviating symptoms 2
• Adults represent a significant reservoir for pertussis transmission to vulnerable populations, particularly infants who have the highest morbidity and mortality from the disease 1