Pertussis, Emergency Medicine

Basics

Description

Acute respiratory tract infection spread by small respiratory droplets
Bacteria (fimbriae) attach to respiratory epithelial cells and proliferate, producing toxins:
- Ciliary dysfunction, accumulation of cellular debris, increased mucus production, lymphocytic and granulocytic infiltration
Bronchiolar congestion, obstruction, and necrosis
Obstruction of the airway due to mucus plug, leading to hypoxia and hypoventilation
Increased intrathoracic or intracranial pressure
Secondary bacterial infection may exacerbate respiratory distress/failure.
CNS injury caused by encephalitis, increased intracranial pressure, and/or hypoxia
Uncomplicated cases last 6 " “10 wk; half of the cases last <6 wk.
Mortality:
- Mortality greatest in those <1 yr
- 1.3% for patients <1 mo
- 0.3% in children 2 " “11 mo
- 90% of deaths are secondary to bacterial pneumonia
Epidemiology:
- Incubation period is 6 " “20 days, usually 7 " “10 days.
- Mostly young children; 24% in children <6 mo
- Increasing incidence in adolescents
- Adults are the primary reservoir
- Peak incidence is late summer/fall
- Preventable with diphtheria " “tetanus " “pertussis (Tdap) vaccine

Etiology

Bordetella pertussis: ‚

A fastidious, gram-negative, pleomorphic bacillus

Diagnosis

Signs and Symptoms

Generally 3 recognized phases with progression:
- Infants may have indistinct stages
Catarrhal stage:
- 1 " “2 wk duration
- Rhinorrhea
- Mild cough
- Minimal fever
Paroxysmal stage:
- 1 " “6 wk duration
- Classic "whooping " ¯ cough, increasing in severity:
  - Coughing spasm that ends with a sudden inflow of air " ”the whoop; unremitting paroxysms
- Cyanosis with respiratory distress/failure
- Apnea (infants <6 mo)
- Altered mental status secondary to hypoxia or encephalitis
Convalescent stage:
- 2 " “12 wk duration
- Waning cough
- Improving respiratory status
Atypical presentations:
- Often atypical in children <6 mo
- Partially immunized children have less severe disease
- Adult manifestations are often only rhinorrhea, sore throat, persistent cough; often in family members

History

Catarrhal phase:
- Malaise
- Low-grade fever
- Rhinorrhea
- Sore throat
Paroxysmal phase:
- "Whooping " ¯ cough
- Post-tussive cyanosis
- Post-tussive emesis
"Whooping " ¯ sound during paroxysmal phase
Catarrhal phase:
- Persistent cough

Physical Exam

Catarrhal phase:
- Low-grade fever
- Rhinorrhea
- Lacrimation
- Dry cough (late phase)
- Conjunctival inflammation
Paroxysmal phase:
- Paroxysmal whooping cough
Convalescent phase:
- Occasional paroxysmal cough

Essential Workup

The ED diagnosis should be made on clinical grounds
Attempt to establish a history of a contact
Observe the paroxysmal cough with the characteristic whoop
Use ancillary studies to further support the clinical diagnosis and exclude complications

Diagnosis Tests & Interpretation

Lab

Polymerase chain reaction:
- High sensitivity and specificity
- High sensitivity leads to more false positives
- Best practices for testing with PCR:
  - Test only those with symptoms
  - Testing after 4 weeks of cough or following antibiotics will increase false negative rate
  - Obtain samples via aspiration or posterior nasopharyngeal swab to maximize DNA recovery
- Should be used in conjunction with culture
Direct immunofluorescence assay of nasopharyngeal mucus:
- High false-positive rate
Culture of nasopharynx or cough plate on a Bordet " “Gengou medium:
- Takes 7 " “12 days
- High specificity
- Low sensitivity
  - Remains the gold standard test
Serology:
- Useful in later diagnosis
- Perform testing 2 " “8 weeks after cough onset
WBC count:
- Leukocytosis (20,000 " “50,000 cells/mm3) with marked lymphocytosis
- Normalizes during convalescent phase
- Elevation of WBC and lymphocytosis parallels severity of cough
Immunofluorescent and enzyme immunoassays to exclude respiratory syncytial virus
Done on either nasal wash or nasopharyngeal swab (Dacron)

Imaging
CXR: ‚

Most often normal
Perihilar infiltrates
Atelectasis
Occasionally characteristic "shaggy " ¯ right heart border
Secondary bacterial pneumonia

Differential Diagnosis

Infection:
- Parallel whooping cough syndrome caused by Bordetella parapertussis, Chlamydia trachomatis, Chlamydia pneumoniae, Bordetella bronchiseptica, or adenovirus
- Pneumonia:
  - Bacteria
  - Mycoplasma
  - Mycobacterium
- Bronchiolitis:
  - Respiratory syncytial virus
  - Influenza
  - Other virus
Reactive airway disease
Foreign body
Cystic fibrosis

Treatment

Pre-Hospital

Oxygen
Monitor airway
Suction

Initial Stabilization/Therapy

Oxygen and respiratory support
Suction mucous plugs

Ed Treatment/Procedures

Universal precautions:
- Specifically requires droplet precautions for 5 days after initiation of antimicrobial therapy
Maintenance of adequate hydration
Monitor oxygenation during paroxysms; supplement oxygen
Airway management may be lifesaving in younger children
Antibiotics:
- Effective in the catarrhal stage
- Prevent further transmission in the paroxysmal stage
- Azithromycin is the first-line agent
- Alternatively, clarithromycin, erythromycin, or trimethoprim " “sulfamethoxazole may be used, although the efficacy is unproven; useful if erythromycin is not tolerated
Corticosteroids and albuterol may reduce paroxysms of coughing, but further studies are required
With increasing incidence of pertussis among adolescents and adults, emergency physicians can decrease incidence of pertussis by making vaccination routine when also vaccinating against tetanus:
- Tetanus toxoid, reduced diphtheria toxoid, acellular pertussis (Tdap)

Medication

Bronchodilators and steroids are generally not recommended for pertussis ‚
First Line

Azithromycin (adult): 500 mg PO day 1, then 250 mg PO QD for 4 days
Azithromycin <5 mo: 10 mg/kg PO daily for 5 days
Azithromycin 5 mo " “adult: 10 mg/kg PO day 1 (max. 500 mg), then 5 mg/kg PO daily for 4 days (max. 250 mg daily)
Tetanus toxoid, reduced diphtheria toxoid, Tdap vaccine: 0.5 mL IM:
- Adacel: Approved for ages 11 and up
- Boostrix: Approved for ages 10 and up

Advisory Committee on Immunization Practices (ACIP) recommends Tdap for pregnant patients during each pregnancy
May be given anytime, but preference is between 27 " “36 weeks gestation

Second Line

Clarithromycin: 15 mg/kg/d div. BID for 7 days (max. 1 g/d)
Erythromycin: 40 " “50 mg/kg/d div. QID for 14 days (max. 2 g/d). Associated with risk of pyloric stenosis when administered in 1st 2 wk of life
Trimethoprim " “sulfamethoxazole: 8/40 mg/kg/d div. BID for 14 days (max. 320/1,600 mg/d):
- Not for infants <2 mo

Follow-Up

Disposition

Admission Criteria

Patients <1 yr
Apnea
Cyanosis during paroxysms of cough
Significant associated pneumonia
Encephalitis

Discharge Criteria

Children without apnea, respiratory compromise, altered mental status, or complications and respiratory distress
Warm liquids to reduce coughing spasm
Remove thick secretions with bulb suction in infants
Good hydration
Avoid cough triggers: Cigarette smoke, pollutants, perfumes
Postexposure prophylaxis is recommended to all persons with close contact (within 3 ft of a symptomatic person):
- Antibiotic recommendations are the same as those with disease
- Symptomatic children should be excluded from school or work; individuals with pertussis may return after 5 days of full treatment

Followup Recommendations

Children who are discharged need close follow-up to monitor hydration status and for respiratory compromise. ‚
Physicians are legally required to report cases of pertussis to state health department. ‚

Complications

Head, eyes, ears, neck, throat:
- Epistaxis
- Subconjunctival hemorrhage
Respiratory:
- Acute respiratory arrest
- Pneumonia caused by secondary infection
- Pneumothorax
- SC or mediastinal emphysema with crepitus
- Bronchiectasis
GI:
- Hernia: Inguinal or abdominal
- Rectal prolapse
Neurologic:
- Seizures
- Encephalitis
- Coma
- Intracranial hemorrhage
- Spinal epidural hemorrhage

The child with pertussis may have significant respiratory distress or apnea ‚

Pearls and Pitfalls

Infants ≤1 yr need admission for pertussis
Tdap should be given to eligible patients requiring tetanus prophylaxis
Droplet precautions should be implemented for 5 days after implementation of effective antimicrobial therapy
Chemoprophylaxis is recommended for all household contacts irrespective of age and immunization status

Additional Reading

Centers for Disease Control and Prevention. Pertussis (Whooping Cough); Best Practice for Health Care Professionals on the use of Polymerase Chain Reaction (PCR) for Diagnosing Pertussis. Available at: http://www.cdc.gov/pertussis/clinical/diagnostic-testing/diagnosis-pcr-bestpractices.html.
Centers for Disease Control and Prevention. Pertussis (Whooping Cough); Diagnosis Confirmation. Available at: http://www.cdc.gov/pertussis/clinical/diagnostic-testing/diagnosis-confirmation.html.
Centers for Disease Control and Prevention. Updated recommendation for use of tetanus toxoid, reduced diptheria toxoid, and acellular Pertussis (Tdap) vaccine in adults aged 65 years and older " “Advisory Committee on Immunization Practices (ACIP), 2012. MMWR. 2012;61:468 " “470.
Centers for Disease Control and Prevention. Updated recommendation for use of tetanus toxoid, reduced diptheria toxoid, and acellular Pertussis (Tdap) vaccine in pregnant women " “Advisory Committee on Immunization Practices (ACIP), 2012. MMWR. 2013;62:131 " “135.
Gregory ‚ DS. Pertussis: A disease affecting all ages. Am Fam Physician. 2006;74:420 " “426.
Klein ‚ NP, Bartlett ‚ J, Rowhani-Rahbar ‚ A, et al. Waning protection after firth dose of acellular pertussis vaccine in children. N Engl J Med. 2012;367:1012 " “1019.
McIntyre ‚ P, Wood ‚ W. Pertussis in early infancy: Disease burden and preventive strategies. Curr Opin Infect Dis. 2009;22:215 " “223.
Shah ‚ S, Sharieff ‚ GQ. Pediatric respiratory infections. Emerg Med Clin North Am. 2007;25:961 " “979.
Wood ‚ N, McIntyre ‚ P. Pertussis: Review of epidemiology, diagnosis, management and prevention. Paediatr Respir Rev. 2008;9:201 " “211.

Codes

ICD9

033.0 Whooping cough due to bordetella pertussis [B. pertussis]
033.1 Whooping cough due to bordetella parapertussis [B. parapertussis]
033.9 Whooping cough, unspecified organism
033.8 Whooping cough due to other specified organism
033 Whooping cough

ICD10

A37.00 Whooping cough due to Bordetella pertussis without pneumonia
A37.10 Whooping cough due to Bordetella parapertussis w/o pneumonia
A37.90 Whooping cough, unspecified species without pneumonia
A37.80 Whooping cough due to other Bordetella species w/o pneumonia
A37.01 Whooping cough due to Bordetella pertussis with pneumonia
A37.0 Whooping cough due to Bordetella pertussis
A37.11 Whooping cough due to Bordetella parapertussis w pneumonia
A37.1 Whooping cough due to Bordetella parapertussis
A37.81 Whooping cough due to oth Bordetella species with pneumonia
A37.8 Whooping cough due to other Bordetella species
A37.91 Whooping cough, unspecified species with pneumonia
A37.9 Whooping cough, unspecified species
A37 Whooping cough

SNOMED

27836007 Pertussis (disorder)
77116006 Infection due to Bordetella parapertussis
82670009 Whooping cough due to organism other than Bordetella pertussis (disorder)
59475000 Pneumonia in pertussis (disorder)

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