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Show detailsContinuing Education Activity
Pertussis, “a violent cough,” also known as whooping cough or “the cough of 100 days,” was first described in the Paris epidemic of 1578. Bordetella pertussis, the causative organism, was discovered in 1906, and a vaccine was developed in the 1940s. Before the pertussis vaccine was developed, pertussis was a major cause of infant morbidity and mortality. This activity describes the presentation and management of pertussis and highlights the interprofessional team's role in treating affected patients and families.
Objectives:
- Identify the etiology of pertussis.
- Assess the typical presentation of a patient with pertussis.
- Differentiate the treatment and management options available for pertussis.
- Communicate interprofessional team strategies for improving care coordination and communication to enhance the care of patients with pertussis and improve patient outcomes.
Introduction
Pertussis, “a violent cough,” also known as whooping cough or “the cough of 100 days,” was first described in the Paris epidemic of 1578. Bordetella pertussis, the causative organism, was discovered in 1906, and a vaccine was developed in the 1940s. Before the pertussis vaccine was developed, pertussis was a major cause of infant morbidity and mortality.[1][2][3] Pertussis is a serious illness with very high morbidity and mortality.
Etiology
The causative organisms of pertussis are 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 “a kennel cough.”[4][5][6]
Humans are the sole reservoir for Bordetella, which is spread via aerosolized droplets produced during a cough. The organism is highly contagious, with most cases occurring during summer.
Risk factors for acquiring pertussis include:
- Pregnancy
- Epidemic exposure
- Lack of immunization
- Close contact with an infected individual
Epidemiology
Reported pertussis cases are increasing in the United States and worldwide. The prevalence of pertussis in the United States sharply declined from 150,000 to 250,000 cases per year in the prevaccination era to 1010 cases reported in 1976. Since then, pertussis has risen, partially attributed to waning adolescent and adult immunity. Although pertussis largely remains a pediatric disease, with 38% of cases occurring in infants younger than 6 months and 71% of cases occurring in children younger than 5 years, adolescents and adults can also contract the disease and are likely contributing to the increasing number of both adult and pediatric cases seen over the past 3 decades. Worldwide, there are over 24 million cases annually, with more than 160,000 deaths. The Centers for Disease Control and Prevention (CDC) reported over 48,000 cases in the United States in 2012, the most recent year for which this data is available. Due to the difficulty in diagnosis, the CDC estimates are likely underreporting.[7]
Pathophysiology
Bordetella is a gram-negative coccobacillus that adheres to ciliated respiratory epithelial cells. Local inflammatory changes occur in the mucosal lining of the respiratory tract. Released toxins (pertussis toxin, dermonecrotic toxin, adenylate cyclase toxin, and tracheal cytotoxin) act locally and systemically. However, the organism itself does not fully penetrate the respiratory tract and rarely is found in blood cultures.
History and Physical
After an incubation period of 1 to 3 weeks, pertussis infection typically progresses through 3 distinct stages: the catarrhal phase, the paroxysmal phase, and the convalescent phase. The catarrhal phase presents similarly to other upper respiratory tract infections, with fever, fatigue, rhinorrhea, and conjunctival injection. It lasts 1 to 2 weeks and is the most infectious stage of the disease. The paroxysmal phase follows the catarrhal phase and is characterized by paroxysms of a staccato cough and the resolution of fever. The patient typically coughs repeatedly, followed by forceful inspiration, which creates the characteristic “whoop.” These episodes may be triggered by cold or noise and are more common at night. Patients are nontoxic-appearing between paroxysms, but may exhibit cyanosis, diaphoresis, or apnea during coughing episodes. Immediately following a paroxysm, patients may develop post-tussive emesis, syncope, or apnea.
Finally, during the convalescent phase, a residual cough persists for weeks to months, usually triggered by exposure to another upper respiratory infection or irritant. Atypical presentations are common in infants, and fever may not occur. Rather, the presenting features may be tachypnea, apnea, cyanosis, and episodic bradycardia. Increased intrathoracic pressure from coughing may result in petechiae above the nipple line, subconjunctival hemorrhage, and epistaxis. Breath sounds are variable. Auscultation may reveal clear lungs or rhonchi, while rales suggest superimposed pneumonia. The inspiratory whoop or gasp is usually heard in children between 6 months and 5 years old.
Evaluation
Testing for pertussis is not readily available in the emergency department. Nasopharyngeal culture and polymerase chain reaction may yield laboratory confirmation. Still, the fastidious and slow-growing Bordetella organisms require specialized media, and cultures are typically not positive for 3 to 7 days. In adults, by the time the diagnosis is suspected, cultures are typically negative (96%), and overall culture sensitivity is only 20% to 40%. Polymerase chain reaction is more sensitive and specific than culture, but testing is not widely available.[8][9][10]
In the emergency department, pertussis should be considered in patients with prolonged cough, especially in paroxysms or with whoops or post-tussive emesis. During the late catarrhal and early paroxysmal phases, leukocytosis (often 25,000 to 60,000 per mL) with lymphocytosis may raise suspicion for pertussis. In a study of 100 infants less than 120 days old and admitted to a pediatric intensive care unit, there was a significantly higher leukocytosis in the 5 fatal cases. Unfortunately, leukocytosis may be the only laboratory finding useful in the emergency department. Chest x-ray findings are nonspecific and may show peribronchial thickening, atelectasis, or infiltrates. Though not often seen, the classic association is a “shaggy” right heart border.
Treatment / Management
Treatment of pertussis is largely supportive, including oxygen, suctioning, hydration, and avoidance of respiratory irritants. Parenteral nutrition may be necessary as the disease tends to persist. Hospitalization is 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 are not fully vaccinated and carry the greatest risk of morbidity and mortality; they should be hospitalized regardless of symptoms. Neonates should be admitted to an intensive care setting as life-threatening cardiopulmonary complications and arrest can occur unexpectedly.
Antibiotic effects on the duration or severity of the disease are minimal when started in the catarrhal phase and not proven effective when started in the paroxysmal phase. Rather, the primary goal of antibiotic treatment is to decrease the carriage and spread of disease. Erythromycin (40 to 50 mg/kg per day, maximum 2 g per day, in 2 to 3 divided doses) is the first-line treatment for pertussis. Azithromycin (10 mg/kg per day on day 1 followed by 5 mg/kg on days 2 to 5) and clarithromycin (15 mg/kg per day in 2 divided doses) are alternative treatments. Trimethoprim-sulfamethoxazole (8 mg/kg per day of trimethoprim) has been used as an alternative in macrolide-allergic patients, but its efficacy has not been proven.
The macrolides are not recommended for infants less than 4 weeks old for fear that this may lead to infantile hypertrophic pyloric stenosis. Strict isolation is important while the patient remains infectious. Pertussis is contagious throughout the catarrhal phase and for 3 weeks after the onset of the paroxysmal phase. In patients treated with antibiotics, isolation should be continued for at least 5 days after initiating treatment. Postexposure prophylaxis with erythromycin is recommended for all household contacts. Corticosteroids have not shown definite benefit in reducing the severity and course of illness but are sometimes given to critically ill infants. Beta2-agonists, pertussis immune globulin, cough suppressants, and antihistamines are ineffective. Exchange blood transfusion therapy for leukocytosis with lymphocytosis may be considered.
Close contacts should be treated with azithromycin or erythromycin. Vaccination with the acellular vaccine is recommended at ages 2,4,6, 15-18 months, and 4 to 6 years. In addition, the CDC recommends a single dose of Tdap for all adults to reduce transmission to children. Adverse effects of the vaccine include crying and febrile seizures, but severe neurological effects are rare. The vaccine can also be administered to pregnant women during the third trimester without harming the fetus. DTaP is approved during the last 3 months of pregnancy to prevent pertussis in infants under 2 months old.
Differential Diagnosis
Pertussis initially presents similarly to other respiratory infections, such as viral upper respiratory infection, bronchiolitis, pneumonia, and tuberculosis. Key differentiating factors of pertussis include typical progression through the 3 phases and persistent cough without fever. Foreign body aspiration should be considered in younger patients, and chronic obstructive pulmonary disease exacerbation should be considered in older patients with the appropriate history. The striking leukocytosis may also be confused with leukemia.
Prognosis
Most people infected with pertussis fully recover, albeit usually after a prolonged illness of months. Infants and older adults tend to have the highest mortality and morbidity, respectively. The infant death rate is about 2% of cases and accounts for 96% of deaths related to pertussis. Older adults tend to have increased morbidity due to other chronic medical conditions and an increased rate of complications, such as pneumonia.[11][12][13] Secondary complications like pneumonia, seizures, and encephalopathy may occur in some patients.
Complications
Secondary pneumonia or otitis media may occur. Superimposed pneumonia is a major cause of mortality in infants and young children. It may be caused by aspiration of gastric contents during paroxysms of cough or because of decreased respiratory clearance of pathogens. Fever should subside during the catarrhal phase, and its presence during the paroxysmal phase should raise suspicion for pneumonia. The most common causes of secondary bacterial pneumonia are Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, and Staphylococcus aureus. However, viral infections with the respiratory syncytial, cytomegalovirus, and adenovirus superinfections are also common.
Rarely (less than 2% of cases) central nervous system complications such as seizures and encephalopathy can occur, likely secondary to hypoxia, hypoglycemia, toxins, secondary infections, or cerebral bleeding from increased pressure during coughing. Sudden increases in intrathoracic and intraabdominal pressures can also result in periorbital edema, pneumothorax, pneumomediastinum, subcutaneous emphysema, diaphragmatic rupture, umbilical and inguinal hernias, and rectal prolapse. Pertussis toxin also causes histamine hypersensitivity and increased insulin secretion. Infants are particularly prone to bradycardia, hypotension, and cardiac arrest from pertussis. The development of pulmonary hypertension has been increasingly recognized as a factor contributing to infantile mortality, as it may lead to worsening systemic hypotension and hypoxia.
Deterrence and Patient Education
The pertussis vaccine exists in both whole-cell and acellular forms. In 1991, the acellular formulation largely replaced the whole-cell vaccine, which was associated with acute encephalopathy and prolonged seizures. The acellular form has fewer adverse effects and is as effective as the whole-cell formulation. As a result, whole-cell preparation is only recommended when the acellular form is unavailable. Common adverse effects are mild and include fever, irritability, behavioral changes, and pain at the injection site. Less commonly, moderately severe reactions, including fever over 40 C, persistent and high-pitched crying, and seizures may occur. A recent study of over 50,000 patients vaccinated from 1981 to 2016 did not detect any new or unexpected adverse effects.
Pearls and Other Issues
Laboratory and radiographic confirmation of pertussis is challenging in the emergency department setting. It is important to maintain a low threshold of suspicion for pertussis in any patient presenting with prolonged cough, regardless of immunization status. A complete blood count with attention to leukocytosis and lymphocytosis may be the best diagnostic screening tool in the emergency department.
Enhancing Healthcare Team Outcomes
The management of pertussis is best done with an interprofessional team that includes the pharmacist and nurses. With a strong anti-vaccine movement, patient education is key. Parents and caregivers must be informed that the vaccine's adverse effects are rare. In an era of anti-vaccination sentiments, clinicians should educate the public that the vaccine is safe and effective. Pertussis immunity wanes significantly about 7 years after vaccination and 15 years after natural infection. As a result, the CDC Advisory Committee on Immunization Practices recommends routine booster immunization, starting at ages 11 to 18 years. A study of almost 70,000 patients showed no significant adverse effects for patients receiving Tdap instead of Td as a tetanus booster; in patients requiring a tetanus booster in the emergency department, adding the acellular pertussis component could be considered, especially in pregnant women. Mothers are often identified as the source of pertussis infection in newborns who have not completed their vaccination series, and preliminary data suggest that infants of mothers vaccinated against both influenza and pertussis may be at lower risk for contracting pertussis. Pertussis is a reportable infection in the US, and even 1 case must be reported immediately, and control measures to prevent transmission should be in place. Open communication between the interprofessional team is vital to ensure that patients are treated with optimal care and that vaccination protocols are in place.
Review Questions
References
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- Hotez PJ. Immunizations and vaccines: a decade of successes and reversals, and a call for 'vaccine diplomacy'. Int Health. 2019 Sep 02;11(5):331-333. [PubMed: 31034023]
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- Xu J, Liu S, Liu Q, Rong R, Tang W, Wang Q, Kuang S, Zhou C. The effectiveness and safety of pertussis booster vaccination for adolescents and adults: A systematic review and meta-analysis. Medicine (Baltimore). 2019 Apr;98(16):e15281. [PMC free article: PMC6494346] [PubMed: 31008974]
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- Dou M, Macias N, Shen F, Bard JD, Domínguez DC, Li X. Rapid and Accurate Diagnosis of the Respiratory Disease Pertussis on a Point-of-Care Biochip. EClinicalMedicine. 2019 Feb;8:72-77. [PMC free article: PMC6469871] [PubMed: 31008450]
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Disclosure: Ashley Lauria declares no relevant financial relationships with ineligible companies.
Disclosure: Christopher Zabbo declares no relevant financial relationships with ineligible companies.
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