Whooping Cough

1. See Also
   1. Bacterial Pneumonia
2. Epidemiology
   1. Pertussis is a common cause of adult Chronic Cough
      1. With waning immunity, teens and adults are reservoir
      2. Most cases occur in over age 10 years
   2. Infants are infected by adults
      1. Infant immunity <1 year is incomplete
      2. Infants comprise >50% of all childhood infections
      3. Infection most severe in infants including death
3. Etiologies
   1. Bordetella pertussis
   2. Bordetella parapertussis
4. Pathophysiology
   1. Incubation period: 7 to 10 days
5. Signs and symptoms
   1. Catarrhal Stage (1-2 weeks)
      1. Low grade fever
      2. Malaise
      3. Mild Conjunctivitis
      4. Rhinitis
      5. Sneezing
      6. Lacrimation
   2. Paroxysmal Cough Stage (2-4 weeks with peak at 2 weeks)
      1. Infants under age 6 months
         1. Apnea
         2. Persistent cough (not in spasms)
         3. Decreased oral intake
      2. Older infants, children and adults
         1. Gradually progressive cough in spasms
         2. Inspiratory whoop (not heard in adults)
         3. Vomiting may occur with severe cough
         4. Cyanosis following coughing spasms
         5. Fine rales on lung exam
         6. CoughSyncope
   3. Convalescent Stage (1-2 weeks)
      1. Coughing spasms resolve over 1-3 months ("80 day cough")
6. Differential Diagnosis
   1. Catarrhal stage
      1. Viral Upper Respiratory Infection (e.g. Adenovirus)
   2. Paroxysmal stage
      1. Mycoplasma pneumoniae
      2. Chlamydia pneumoniae
   3. Convalescent stage with persistent cough
      1. Asthma
      2. Gastroesophageal Reflux
      3. Acute Sinusitis with post nasal drainage
7. Diagnosis
   1. See Bordetella Pertussis Test
   2. Treatment and reporting based on clinical suspicion
   3. Clinical suspicion criteria
      1. Major Criteria: Acute cough for 14 days
      2. Minor criteria (requires one)
         1. Paroxysmal cough
         2. Post-tussive Emesis
         3. Inspiratory Whoop
         4. Pertussis outbreak
8. Management
   1. Pertussis is a clinical diagnosis (see diagnosis above)
      1. Treatment and reporting based on clinical suspicion
      2. Report clinically suspected cases before confirmation
      3. Start antibiotics before confirmation if suspected
   2. Antibiotic Course
      1. Fourteen days is considered standard for Erythromycin
         1. American academy of pediatrics recommends 14 days
      2. Seven Day course appears as effective for eradication
         1. Halperin (1997) Pediatrics 100:65-71
      3. Start treatment early (best efficacy)
   3. Pediatric antibiotic dosing
      1. Azithromycin for 5 days (preferred)
      2. Clarithromycin for 14 days
      3. Erythromycin
         1. Child: 40-50 mg/kg/day divided qid for 14 days
         2. Adults: 500 mg PO qid for 14 days
      4. Bactrim (not as effective as Macrolides)
         1. Indicated for Macrolide allergy or GI intolerance
         2. Do not use in pregnancy, Lactation, age <2 months
         3. Dosing
            1. Child: 8 mg/kg Trimethoprim divided bid x14 days
            2. Adult: Bactrim DS one tablet bid for 14 days
            3. Maximum dose: 320/1600 mg TMP/SMX
9. Management: Prevention of spread
   1. Quarantine
      1. Pertussis patients are off work and out of school
      2. May return after 5 days on antibiotics or
      3. Three weeks after paroxysmal stage ends
   2. Prophyaxis: Treat close contacts with exposure within 3 weeks
      1. Contacts are positive, yet asymptomatic
      2. Use same antibiotic course as above
      3. Monitor contacts for 20 days for onset of symptoms
10. Prevention
    1. Diphtheria Tetanus Acellular Pertussis Vaccine (DTaP)
       1. Primary Series for 5 doses by age 5 years
    2. Tdap (Boostrix, Adacel)
       1. Use for 12 year old booster (instead of Td)
       2. Give Adacel once as booster in age 19-65 years
          1. Can replace one Td booster
11. Complications (usually limited to infants)
    1. Hospitalization
    2. Superimposed Bacterial Pneumonia
    3. Dehydration
    4. Encephalopathy
    5. Death (rate has rising for infants)
12. References
    1. Gilbert (2001) Sanford Antimicrobial, p. 25
    2. Birkebaek (1999) Clin Infect Dis 29:1239-42
    3. Gregory (2006) Am Fam Physician 74:420-7