Pertussis

Background

  • “Whooping cough”. The “whoop” is caused on inspiration between coughs.[1]
  • Most common in kids < 1yo, because they haven’t completed the whole vaccine series, AND adults, who have waning immunity.
  • One of the only vaccine preventable diseases that has increased in prevalence recently
  • Up to 20% of adults with cough >2 weeks have serologic evidence of pertussis[2]
  • Bordetella pertussis, a gram-negative coccobacillus


Pathophysiology

  • Transmitted by aerosolized droplets, extremely contagious
  • Infects ciliated respiratory cells (rarely goes hematogenous), creates toxins damaging respiratory epithelium.

Clinical Features[3]

A young boy coughing due to pertussis.
  • Incubation period several days-3 weeks
  • 3 stages:
    • Catarrhal phase: lasts 1-2 wks. Clinically indistinguishable from other URIs; dry cough starts near the end. Greatest infectivity phase.
    • Paroxysmal phase: lasts 2-4 weeks => fever improves, cough worsens. Staccato cough + whoop (present in 1/3 kids), post-tussive emesis (often in adolescents, adults). Infants can present as apnea. Patients often appear well between coughing episodes.
      • Petechiae, epistaxis, pneumothorax, and/or subconjunctival hemorrhage may occur due to high intrathoracic pressures during coughing.
    • Convalescent phase: lasts weeks-months; residual cough

Sequelae

  • Pneumonia superinfections
  • Rib fracture
  • Pneumothorax
  • Aspiration of gastric contents
  • CNS complications
  • Mucous plugs, obstructed airway
  • Secondary bacterial infection
  • Increased intrathoracic pressures
    • Rectal prolapse
    • Ruptured diaphragm
    • Hernia

Differential Diagnosis

Pediatric fever

Evaluation

  • WBC elevated in infants (20-100) with large amount of lymphs (85%), adults and infants < 6 mo may be WNL
  • CXR with peribronchial thickening, atelectasis, and/or consolidation
  • Nasopharyngeal swab can identify it in 3-7 days; often neg in adults.
  • Cough for >2 weeks, post tussive emesis, feeling well otherwise, treat them empirically. Especially if infant or pregnant people at home.

Management[4]

Acute Disease

  • Supportive
    • Suction in infants, hydration. Neonates with apnea should be admitted to the ICU.

Antibiotics

  • Antibiotics do not help with severity or duration but may decrease infectivity.
  • A reasonable guideline is to treat persons aged >1 year within 3 weeks of cough onset and infants aged <1 year and pregnant women (especially near term) within 6 weeks of cough onset. [5]
  • TMP--SMZ should not be administered to pregnant women, nursing mothers, or infants aged <2 months.[6]
  • The following regemins are for active disease or postexposure prophylaxis. If a patient is has confirmed disease and is likely to be in contact with infants or pregnant women then the patient should be treated as up to 6-8 weeks after the onset of their illness.

< 1 month old

Same antibiotics for active disease and postexposure prophylaxis

>1 month old

  • Azithromycin 10mg/kg (max 500mg/day) daily x 5 days
    • if > 6 months old then day 2-5 of treatment should be reduced to 5mg/kg (250mg/day max)
  • TMP/SMX 4mg/kg PO BID daily for 14 days (if > 2 months old)

Adults

andy of the following antibiotics are acceptable although azithromycin is most commonly prescribed

Isolation

  • Droplet

Post-Exposure Prophylaxis[7]

  • Prophylaxis for all household exposures of known Pertussis
  • High risk people exposed to pertussis: infants, women in 3rd trimester of pregnancy, immunocompromised, severe asthma, people with close contact to infants <1year, people who work in neonatal ICUs / maternity wards.
  • Patients are considered considerably less infectious 3 wks after start of paroxysmal phase, or after 5 days of antibiotics

Prevention

  • Vaccinate women during each pregnancy preferably between 27-36 wks, regardless of previous Tdap admin
  • Immunity wanes 8 y after immunization. Often elderly will get the disease and transmit it to young unimmunized infants.

Tetanus Vaccine Selection Guide

Age If No Pertussis Contraindications If Pertussis Contraindicated Comments
2mo - 7yrs DTaP DT DT available from pharmacy
7yrs - 10yrs Td Td
10yrs Tdap(Adacel)^ Td ^Off label use, but appears safe and immunogenic
11yrs - 16yrs Tdap(Adacel) Td
16yrs - 65 Tdap(Adacel)^^ Td ^^Use Td if patient is known to have received prior Tdap
65yrs + Td
Td
Consider TIG for tetanus prone wound plus Td(tetanus immune globulin)

Caveats

  • Adolescents who have already gotten a booster dose of Td are encouraged to get a dose of Tdap as well. Waiting 5 years after their last Td is encouraged but not required. A period of at least 2 years between Td and Tdap is recommended in these cases.
  • Pregnancy is not a contraindication to Tdap.
  • Stable neurologic disorders and family history of vaccine reactions are not contraindications to receiving these vaccines.
  • No vaccine has ever been shown to play any role in the development of autism or autism spectrum disorders.

See Also

References

  1. Frumkin K. Pertussis and persistent cough: practical, clinical and epidemiologic issues. J Emerg Med. 2013 Apr;44(4):889-95.
  2. Trends in hospitalizations and resource utilization for pediatric pertussis. Hosp Pediatr. 2014 Sep;4(5):269-75
  3. “Pertussis: Clinical Features”. Centers for Disease Control and Prevention. http://www.cdc.gov/pertussis/clinical/features.html. Sept 4, 2014
  4. *“Pertussis Treatment Options”. British Medical Journal Best Practice. http://bestpractice.bmj.com/best-practice/monograph/682/treatment.html. Sept 3, 2014.
  5. CDC - Pertussis http://www.cdc.gov/pertussis/clinical/treatment.html
  6. CDC MMWR Pertusis http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5414a1.htm
  7. “ Pertussis Postexposure Antimicrobial Prophylaxis”. Centers for Disease Control and Prevention. http://www.cdc.gov/pertussis/outbreaks/pep.html. Aug 28, 2013