Question

Which of the following statements about Bordetella pertussis infection is true? A. Infection causes a leukocytosis characterized primarily by a marked elevation in polymorphonuclear leukocytes. B. Isolation of the organism from clinical specimens is greatest during the early stages of illness. C. Clinical diagnosis of whooping cough can usually be made within a few days of onset of initial symptoms. D. Children who receive a full series of immunizations with the pertussis vaccine generally develop solid, lifelong immunity to pertussis. E. The organism can be cultured on standard laboratory media such as sheep blood agar.

Short answer

The correct statement about Bordetella pertussis infection is: Isolation of the organism from clinical specimens is greatest during the early stages of illness.

Step-by-step solution

Analyze each statement based on known facts about Bordetella pertussis and its associated infection

A) Bordetella pertussis infection does cause leukocytosis but it's characterized by a marked elevation in lymphocytes, not polymorphonuclear leukocytes. So, this statement is incorrect. B) The isolation of Bordetella pertussis is indeed greater during the early stages of the disease. The bacterium can most likely be isolated in the catarrhal stage and at the beginning of the paroxysmal stage. Therefore, this statement is correct. C) The clinical diagnosis of whooping cough isn't easily made within a few days of onset of initial symptoms because these symptoms are nonspecific and resemble those of common colds. So, this statement isn't true. D) Immunization against pertussis does provide initial immunity but this immunity wanes after 5-10 years, hence lifelong immunity isn't ensured. This statement is therefore incorrect. E) Bordetella pertussis is not easily cultured on standard lab media. It requires a special medium called Bordet-Gengou medium. Hence, this statement is incorrect.

Validate the correct statement

Statement B is the only correct statement among the given set of statements about Bordetella pertussis infection.

Key concepts

Leukocytosis in Infection

Leukocytosis refers to an increased white blood cell count, which often occurs as a response to infection. In the case of Bordetella pertussis infection, commonly known as whooping cough, this leukocytosis is characterized by an elevation in lymphocytes. Unlike other bacterial infections where there is a rise in polymorphonuclear leukocytes (like neutrophils), whooping cough uniquely causes a lymphocytosis. This is a key point to remember as it helps in distinguishing Bordetella pertussis from other infections when analyzing blood test results.
Bordetella pertussis impacts the lymphatic system, causing an immune reaction that results in this increase in lymphocytes. It's part of the body's immune response aiming to fight the infection, which can be a useful indicator for medical professionals when they suspect whooping cough.

Early Stage Isolation

Isolating Bordetella pertussis is most successful during the early stages of the infection. Specifically, the bacterium can be isolated most easily during the catarrhal stage, which is the first phase of the illness. During this time, patients might display symptoms akin to a common cold, making a swift diagnosis challenging.
Early isolation is crucial because it facilitates the accurate identification of the bacterium through laboratory cultures. This is not only important for confirming the diagnosis but also for controlling the spread of the infection since Bordetella pertussis is highly contagious.

• Catarrhal stage: Best time for isolation
• Driven by early symptoms like sneezing and runny nose

Once the paroxysmal stage begins, which is characterized by severe coughing fits, the chances of isolating the bacterium decrease.

Clinical Diagnosis Challenges

Diagnosing Bordetella pertussis in its early stages poses significant challenges. Initial symptoms often mimic those of a cold or a mild respiratory infection. These include runny nose, mild cough, and sneezing, which are non-specific and do not immediately suggest whooping cough.
This overlap in symptoms with more common infections leads to potential misdiagnosis, delaying appropriate treatment and isolation. As the disease progresses into the paroxysmal stage, the hallmark coughing fits become more apparent, aiding clinical diagnosis. However, by this time, early containment and prevention of the spread are harder to manage.
To aid early diagnosis, health professionals often rely on laboratory testing and carefully assessing symptoms as they emerge, although definitive tests such as cultures or PCR may take time.

Pertussis Vaccine Immunity

The pertussis vaccine is instrumental in controlling the spread of Bordetella pertussis infections. However, it's important to understand that it does not provide lifelong immunity. Most childhood vaccines require booster doses to maintain immunity, and the pertussis vaccine is no different.
Initial immunity achieved through vaccination wanes after 5 to 10 years. Consequently, individuals may become susceptible to whooping cough again, emphasizing the need for booster vaccinations. This is why booster shots are recommended, especially in adolescents and adults, to prevent outbreaks.

• Initial vaccines provide strong protection
• Immunity decreases over time
• Regular booster shots are crucial

This information is vital in public health planning and for individuals to take proactive steps in maintaining their immunity against pertussis over their lifetime.