Comments
INITIAL SYMPTOMS:
Paroxysmal coughing may last 1-2 months. Sputum production & vomiting after a coughing spell; [CCDM] Catarrhal phase: mild fever; Paroxysmal phase: no fever; Best predictor in adults is prolonged coughing with vomiting. [Harrison ID]
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. 2622-3] 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. 677] Infants and young children can develop pertussis pneumonia and pulmonary hypertension. [Cecil, p. 1901]
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. In the future, booster doses of vaccines to adolescents and adults will control pertussis in well-immunized populations. [Cecil, p. 1902] 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. 528-9] "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]
For updated text and symptoms of infectious diseases, see iddx.com.