Pertussis (Whooping cough) is a childhood infection. It is vaccine preventable. The catarrhal stage includes runny nose, conjunctival injection, low-grade fever, and sneezing. The paroxysmal stage with dry cough develops after the first week and may last 1-2 mo. Fever is often absent.
CASES/YEAR
700,000 (US); 4,900,000 (Global)
OTHER NAMES
Whooping cough; Bordetella pertussis infection;
INCUBATION
6 days to 3 weeks; average 7-10 days; [CDC Travel]
INITIAL SYMPTOMS
Paroxysmal coughing may last 1-2 mo. Sputum production & vomiting after a coughing spell; [CCDM] Catarrhal phase: mild fever; Paroxysmal phase: no fever; Best predictor in adults is prolonged coughing & vomiting. [Harrison ID, p. 504]
PRECAUTIONS
Droplet; "Single patient room preferred. Cohorting an option. Post-exposure chemoprophylaxis for household contacts and HCWs with prolonged exposure to respiratory secretions." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
FINDINGS:
The catarrhal stage includes runny nose, conjunctival injection, and sneezing. The paroxysmal stage with dry cough develops after the first week. Fever is often absent. [ID, p. 1746] In children, low-grade fever is typically present in the catarrhal stage. Complications of forceful coughing include subconjunctival hemorrhages, syncope, and rib fractures. Infants may present with gasping, cyanosis, and apnea. Encephalopathy is a rare complication (seizures, paralysis, blindness, etc.). Adults have coughing for an average of 36-48 days. [PPID, p. 2796-7] Complications in unimmunized infants and children include pneumonia, encephalopathy, seizures, weight loss, and death. [CCDM, p. 449-54] Cultures should be collected in the first 2 weeks of the illness. [Wallach, p. 1256] Infants and young children can develop pertussis pneumonia and pulmonary hypertension. [Cecil, p. 1961]
PREVENTION:
Estimated case-fatality rate is 3.7% for children younger than 1 year in developing countries. [CCDM, p. 449] "Pertussis is highly contagious; secondary attack rates exceed 80% in susceptible household contacts. . . . Pertussis should be considered for any person seeking treatment with an acute cough lasting at least 7 days, particularly if accompanied by paroxysms of coughing, inspiratory whoop, or posttussive vomiting" [Guidelines for Infection Control in Health Care Personnel. CDC. 1998] "Regardless of age, HCP should receive a single dose of Tdap as soon as feasible if they have not previously received Tdap and regardless of the time since their most recent Td vaccination. . . . Tdap is not licensed for multiple administrations;" HCP with active pertussis are excluded from duty from "beginning of catarrhal stage through third week after onset of paroxysms or until 5 days after start of effective antimicrobial therapy." Recommended antibiotics are azithromycin, clarithromycin, or erythromycin. [ACIP, 2011] Chemoprophylaxis is important for controlling hospital and community outbreaks. [Cecil, p. 1962] Whole-cell vaccines are effective and still used in many countries. Acellular vaccines have lower adverse effects. For adolescents and adults, the vaccine is given as Tdap (tetanus-diphtheria-acellular pertussis). High-risk patients in which it is important to eradicate pertussis: infants, healthcare workers, and 3rd trimester pregnant women; [ABX Guide]
LABORATORY DIAGNOSIS:
Lymphocytosis is common in young children. Culture is the gold standard. The period in which cultures are sensitive (mainly the catarrhal phase) is brief. False-positive PCRs have caused "pseudo-outbreaks." B. pertussis cultures are sensitive to drying--send specimens to the lab as soon as possible. [Harrison ID, p. 505] "Single-point serology results should be interpreted with caution as they do not differentiate between antibodies due to vaccination and those due to infection." [CCDM, p. 450]
DIAGNOSTIC
Culture (60% sensitive); PCR; DFA not recommended because of inaccuracy; Paired sera; Single point anti-PT antibodies useful; [CCDM] Culture (gold standard) w/i 2 wks of cough onset & PCR on nasopharyngeal aspirate w/i 3 wks of cough onset; [5MCC-2020]
SCOPE
Global; Highest incidence among young children in developing countries where vaccination coverage is low; [CDC Travel, p. 304]
SIGNS & SYMPTOMS
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>fatigue, weakness
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>fever
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E rhinitis
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G nausea, vomiting
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H leukocytosis
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N seizure
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O conjunctivitis, acute
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R cough
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R sputum production
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X lung infiltrates
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*blindness
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*paralysis
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*pneumonia
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*weight loss
ENTRY
Inhalation, Skin or Mucous Membranes (Includes Conjunctiva)
RISK FACTORS
- Care for patients (droplet/airborne)
- Fail to complete immunizations
- Live together in close quarters
- Travel to endemic area
- Work in a medical or research lab
TREATMENT
Antibiotics do not usually alter the course of the illness unless started before the paroxysmal phase. [Cecil, p. 1962]
REFERENCES FOR CASES/YEAR
1. (US) Published in MMWR 2011 =18,719; Cases dropped by >95% in US after universal childhood immunizations; One study in US estimated 600,000 to 800,000 cases of pertussis in adults in the US. [Harrison ID, p. 503]
2. (Global) WHO estimates 195,000 deaths in children in 2008; Immunization rates still <50% in many developing countries. [Harrison ID, p. 502] In the US before standard immunizations, 115,000 to 270,000 (average 193,000) cases per year and 5,000 to 10,000 deaths (average 7500); [ID, p. 1745] Calculate: 7500/193,000 = 4% mortality. 0.04x = 195,000; x = 4.9 million;