Pertussis Infection and Immunity

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Questions and Answers

Which of the following organisms is commonly known as 'kennel cough'?

Bordetella bronchiseptica (correct)

Bordetella catarrhalis

Bordetella pertussis

Bordetella parapertussis

What is the percentage of non-immune household contacts that are affected by pertussis?

75%

100% (correct)

50%

80%

After completing a vaccination series, what percentage of immunity wanes after 12 years?

30%

50% (correct)

75%

20%

What is the primary mode of transmission of Bordetella?

Airborne droplets Signup and view all the answers

What is the typical duration of the catarrhal phase of pertussis?

1 to 2 weeks Signup and view all the answers

What is the characteristic sound heard during paroxysms of coughing in pertussis?

Whoop Signup and view all the answers

What is the typical trigger for episodes of paroxysmal coughing in pertussis?

Cold or noise Signup and view all the answers

What is the typical duration of the residual cough in the convalescent phase of pertussis?

Weeks to months Signup and view all the answers

What is the typical age range for the inspiratory whoop or gasp in children?

6 months to 5 years old Signup and view all the answers

What is the sensitivity of nasopharyngeal cultures in diagnosing pertussis?

20% to 40% Signup and view all the answers

What is the primary goal of antibiotic treatment in pertussis?

To decrease the carriage and spread of disease Signup and view all the answers

What is the typical range of leukocytosis in patients with pertussis?

25,000 to 60,000 per mL Signup and view all the answers

What is the indication for hospitalization in patients with pertussis?

For patients with hypoxia, central nervous system complications, or who are unable to tolerate nutrition and hydration by mouth Signup and view all the answers

What is the recommended treatment for pertussis in macrolide-allergic patients?

Trimethoprim-sulfamethoxazole Signup and view all the answers

What is the recommended duration of isolation for patients treated with antibiotics?

At least 5 days Signup and view all the answers

What is the recommended postexposure prophylaxis for household contacts?

Erythromycin Signup and view all the answers

What is the characteristic chest x-ray finding in pertussis?

A 'shaggy' right heart border Signup and view all the answers

Why are macrolides not recommended for infants less than 4 weeks old?

Fear of infantile hypertrophic pyloric stenosis Signup and view all the answers

What is the primary reason for vaccination with the acellular vaccine at ages 2, 4, 6, 15-18 months, and 4 to 6 years?

To protect against pertussis in children under 2 months old Signup and view all the answers

What is the main complication of pertussis that can lead to worsening systemic hypotension and hypoxia in infants?

Pulmonary hypertension Signup and view all the answers

What is the effect of pertussis toxin on histamine?

Hypersensitivity Signup and view all the answers

What is the recommended treatment for close contacts of pertussis patients?

Azithromycin or erythromycin Signup and view all the answers

What is the main cause of mortality in infants and young children with pertussis?

Superimposed pneumonia Signup and view all the answers

What is the recommended timing for DTaP vaccination during pregnancy?

During the last 3 months of pregnancy Signup and view all the answers

What is the effect of pertussis toxin on insulin secretion?

Increased insulin secretion Signup and view all the answers

What is the complication of pertussis that can result in subcutaneous emphysema?

Sudden increase in intrathoracic pressure Signup and view all the answers

Study Notes

Etiology

Causative organisms of pertussis: Bordetella pertussis and Bordetella parapertussis
Bordetella is spread by airborne droplets and is highly contagious
Pertussis often affects 100% of non-immune household contacts
Immunity wanes to 50% 12 years after completing a vaccination series
Immunocompromised persons can also contract Bordetella bronchiseptica, which typically affects animals and is commonly known as “kennel cough”

History and Physical

Incubation period: 1 to 3 weeks
Three distinct stages: catarrhal phase, paroxysmal phase, and convalescent phase
Catarrhal phase: fever, fatigue, rhinorrhea, and conjunctival injection, lasts 1 to 2 weeks
Paroxysmal phase: paroxysms of staccato cough, resolution of fever, and characteristic “whoop”
Patients are nontoxic-appearing between paroxysms, but may exhibit cyanosis, diaphoresis, or apnea during coughing episodes
Convalescent phase: residual cough persists for weeks to months, triggered by exposure to another upper respiratory infection or irritant
Atypical presentations common in infants: tachypnea, apnea, cyanosis, and episodic bradycardia
Increased intrathoracic pressure from coughing may result in petechiae, subconjunctival hemorrhage, and epistaxis

Evaluation

Testing for pertussis: not readily available in the emergency department
Nasopharyngeal culture and polymerase chain reaction may yield laboratory confirmation
Cultures require specialized media, typically not positive for 3 to 7 days
Polymerase chain reaction is more sensitive and specific than culture
Leukocytosis with lymphocytosis may raise suspicion for pertussis
Chest x-ray findings: nonspecific, may show peribronchial thickening, atelectasis, or infiltrates

Treatment / Management

Treatment is largely supportive: oxygen, suctioning, hydration, and avoidance of respiratory irritants
Parenteral nutrition may be necessary
Hospitalization indicated for patients with superimposed pneumonia, hypoxia, central nervous system complications, or who are unable to tolerate nutrition and hydration by mouth
Patients less than 1 year old: should be hospitalized regardless of symptoms
Neonates: should be admitted to an intensive care setting
Antibiotics: decrease the carriage and spread of disease, not proven effective when started in the paroxysmal phase
First-line treatment: erythromycin (40 to 50 mg/kg per day, maximum 2 g per day, in 2 to 3 divided doses)
Alternative treatments: azithromycin, clarithromycin, and trimethoprim-sulfamethoxazole
Macrolides not recommended for infants less than 4 weeks old
Strict isolation important while the patient remains infectious
Postexposure prophylaxis with erythromycin recommended for all household contacts

Complications

Secondary pneumonia or otitis media may occur
Superimposed pneumonia: a major cause of mortality in infants and young children
Fever should subside during the catarrhal phase, and its presence during the paroxysmal phase should raise suspicion for pneumonia
Central nervous system complications: seizures, encephalopathy, and cerebral bleeding
Rare complications: periorbital edema, pneumothorax, pneumomediastinum, subcutaneous emphysema, diaphragmatic rupture, umbilical and inguinal hernias, and rectal prolapse
Pertussis toxin causes histamine hypersensitivity and increased insulin secretion
Infants are particularly prone to bradycardia, hypotension, and cardiac arrest
Development of pulmonary hypertension: a factor contributing to infantile mortality

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Description

Learn about the causes and transmission of pertussis, a contagious respiratory disease, and how immunity works against it.