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Questions and Answers
What is the meaning of the term pertussis?
Pertussis means 'intense cough'.
What type of organism is Bordetella pertussis?
Bordetella pertussis is a small, fastidious, gram-negative coccobacillus.
What is the major virulence protein expressed by B. pertussis?
The major virulence protein is pertussis toxin (PT).
What are the three clinical stages of pertussis?
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What distinguishes the paroxysmal stage of pertussis?
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What is the typical duration of the catarrhal stage of pertussis?
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How contagious is pertussis, and what is the attack rate among susceptible individuals?
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What symptom marks the onset of the paroxysmal stage of pertussis?
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What percentage of infections may remain subclinical even in vaccinated individuals after exposure?
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What kinds of symptoms are included in the catarrhal stage of pertussis?
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Study Notes
Pertussis (Bordetella pertussis)
- Pertussis is a respiratory infection caused by the bacterium Bordetella pertussis.
- The name "pertussis" means "intense cough" and is preferred over "whooping cough" as many patients don't produce the "whooping" sound.
Pathogenesis
- Bordetella organisms are gram-negative bacteria that prefer to live in the ciliated epithelium of the respiratory tract.
- The exact mechanism of how symptoms develop is still unknown.
- Bordetella species share similar virulence genes, but only B. pertussis produces pertussis toxin (PT).
- PT is a major virulence factor and plays a role in several processes like histamine sensitivity, insulin secretion, and leukocyte dysfunction.
- Pertussis is highly contagious, with almost 100% infection rates in susceptible individuals exposed to infected droplets.
- Even when vaccinated with acellular vaccines, high transmission rates are observed in a baboon model of pertussis.
- B. pertussis cannot survive long in the environment and chronic carriage by humans is not documented.
- After intense exposure, such as in households, up to 80% of fully immunized or previously infected individuals can have subclinical infections.
- Most patients typically have a symptomatic source, such as a sibling or related adult.
Clinical Manifestations
- Pertussis is a prolonged illness typically divided into three stages: catarrhal, paroxysmal, and convalescent.
- The catarrhal stage (1-2 weeks) begins after 3-12 days of incubation with mild symptoms like congestion, runny nose, low-grade fever, sneezing, watery eyes, and red eyes.
- As initial symptoms subside, coughing marks the beginning of the paroxysmal stage (2-6 weeks).
- The cough starts as a dry, intermittent, irritating cough, eventually evolving into the characteristic paroxysms of pertussis.
- During a paroxysm, a seemingly healthy child suddenly experiences a burst of uninterrupted cough with forceful exhalations, facial contortions, bulging eyes, and occasional whooping sounds due to forced inhalation.
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Description
This quiz covers the details of pertussis, including its causative agent Bordetella pertussis, symptoms, and transmission. Explore the pathogenesis of this highly contagious respiratory infection and learn about its major virulence factors, particularly pertussis toxin. Test your knowledge about this important infectious disease.
