Whooping Cough (Pertussis) Notes

Overview of Whooping Cough (Pertussis)

  • Definition: Pertussis, commonly known as whooping cough, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis.

Phases of Pertussis

  • Incubation Period: Lasts from 3 to 21 days, during which the patient may appear healthy without symptoms.

  • Catarrhal Stage (1 to 2 weeks):

    • Initial phase resembles common cold symptoms, primarily a runny nose.
    • Bacteria infect the respiratory tract and start to multiply.

  • Paroxysmal Stage:

    • Characterized by severe, uncontrollable coughing fits known as paroxysms.
    • The name "whooping cough" arises from the whooping sound made when a patient tries to inhale between coughs.
    • This stage can lead to serious complications, especially in vulnerable populations.

  • Convalescent Phase:

    • Recovery phase where the number of bacteria decreases.
    • Patients remain susceptible to other respiratory infections due to a weakened immune system following the infection.

Epidemiology

  • Historical Context: Pertussis was nearly eradicated in the 1970s following the introduction of the first vaccine in the 1950s. However, it has resurged due to fluctuating vaccination rates.
  • Presentation in Older Individuals: Adolescents and adults might experience atypical symptoms, especially if they were vaccinated as children.
    • It is estimated that 13% to 20% of bronchitis cases in adults could be misdiagnosed cases of pertussis.

Pathogen Characteristics

  • Causative Organism:
    • Bordetella pertussis, classified as a Gram-negative bacterium.
  • Virulence Factors:
    • Fimbrial Hemagglutinin: Aids in adhesion to respiratory epithelial cells.
    • Pertussis Toxin: Disrupts cellular signaling and contributes to cough severity.
    • Tracheal Cytotoxin: Destroys ciliated epithelial cells, worsening respiratory symptoms.
    • Endotoxin: Part of the bacterial structure that can provoke an immune response.

Diagnosis and Treatment

  • Diagnosis Methods:

    • Confirmed via PCR testing or culture methods on specific media such as B-G, charcoal, or potato-glycerol agar.
    • Clinical diagnosis can also be made based on characteristic coughing symptoms.

  • Prevention:

    • Use of an acellular vaccine (DTaP) is the primary preventive measure.

  • Treatment Options:

    • Antibiotics such as azithromycin or erythromycin are prescribed for affected individuals, particularly for those in close contact.
    • These medications are on the CDC's list of concerning antibiotics due to resistance patterns.

Current Trends

  • Epidemiological Features:
    • Pertussis is resurging in the United States and many other countries, with a similar gradual increase globally.
    • Awareness and vaccination practices are crucial for mitigation of outbreaks.