Jan 7, 2025 Pertussis

mom holding a coughing child

Renuka Verma, MDRenuka Verma, MD
Section Chief Pediatric Infectious Disease,
Monmouth Medical Center

Pertussis or whooping cough, begins with mild upper respiratory tract symptoms and progresses to cough, usually paroxysms of cough (paroxysmal stage), characterized by inspiratory whoop (gasping) after repeated cough on the same breath, which commonly is followed by post-tussive emesis. Fever is not common. Symptoms in immunized children and adults are variable. The duration of classic pertussis is 6 to 10 weeks. Complications among adolescents and adults include syncope, weight loss, sleep disturbance, incontinence, rib fractures, and pneumonia.

Pertussis is most severe in infants, particularly in preterm and unimmunized infants, and can be atypical with a short catarrhal stage, followed by gagging, gasping, bradycardia, or apnea as prominent early manifestations; absence of whoop; and prolonged convalescence. Complications among infants include pneumonia, pulmonary hypertension, and severe coughing spells with associated conjunctival hemorrhage, hernia, and hypoxia. Seizures, encephalopathy, apnea, acute respiratory distress syndrome, and death can occur in infants with pertussis.

Etiology and Pathogenesis

Bordetella pertussis, a gram-negative coccobacillus, causes pertussis through a complex interplay of virulence factors.

Key pathogenic mechanisms include:

  1. Adhesins (filamentous hemagglutinin, pertactin, fimbriae) facilitating attachment to ciliated respiratory epithelium.
  2. Toxins:
    • Pertussis toxin (PT): Leading to lymphocytosis and altered immune responses.
    • Adenylate cyclase toxin: Impairs neutrophil function and induces apoptosis in macrophages
    • Tracheal cytotoxin: Causes ciliary paralysis and epithelial damage.

Epidemiology and Transmission

  • Global resurgence noted, with significant genotypic changes in circulating strains.
  • Shift towards adolescent and adult cases due to waning immunity.
  • R0 (R- naught) estimated between 15-17, highlighting high transmissibility.
  • Asymptomatic transmission recognized as a significant factor in disease spread.

Diagnosis

  • PCR: High sensitivity, rapid results, but potential for false positives.
  • Culture: Gold standard for specificity, essential for antibiotic susceptibility and molecular epidemiology.
  • Serology: Limited utility in acute diagnosis; valuable for epidemiological studies.

Treatment Considerations

  • Macrolides remain first-line treatment and post exposure prophylaxis.
  • Azithromycin preferred due to shorter course and better compliance profile.
  • Antimicrobial resistance emerging, particularly in B. holmesii, a related species causing pertussis-like illness.

Vaccine

Five doses of pertussis containing vaccine are recommended prior to entering school. The first dose of DTaP may be administered as early as 6 weeks of age, followed by 2 additional doses at intervals of approximately 2 months. The fourth dose of DTaP is recommended at 15 through 18 months of age, and the fifth dose of DTaP is administered at 4 through 6 years of age. The fourth dose can be administered as early as 12 months of age, provided 6 months have elapsed since the third dose was administered. If the fourth dose of pertussis vaccine is delayed until after the fourth birthday, the fifth dose is not recommended.

Adverse Events After DTaP Immunization

  • Local and febrile reactions: Include redness, swelling, induration, and tenderness at the injection site as well as drowsiness and irritability.
  • Limb swelling involving the entire thigh or upper arm after administration of the fourth and fifth doses of DTaP, resolves spontaneously and has no sequelae. Entire limb swelling is not a contraindication to further DTaP, Tdap, or Td immunization.
  • Other reactions. Severe anaphylactic reactions are rare. Transient urticarial rashes that occur occasionally.

Public Health Strategies

  • Maternal immunization: Highly effective in protecting young infants, but optimal timing still under investigation.
  • Healthcare worker vaccination: Critical for nosocomial transmission prevention.

The ASP, representing pediatric providers, including pediatric infectious disease specialists and pharmacists, exchange ideas, discuss case management strategies and develop and implement guidelines to be shared system wide, as well as serve as a resource for community physicians.

For more educational information, research and best practices from the Children’s Health Network at RWJBarnabas Health, visit rwjbh.org/childrenshealthresearch.