Applied Evidence

Staying ahead of pertussis

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In recent years, pertussis has been on the rise. Here’s what you can do to help limit the spread of the disease, and how to promptly diagnose and treat it.


 

References

PRACTICE RECOMMENDATIONS

› Recommend a
 one-time Tdap (tetanus-diphtheria-acellular pertussis) combination vaccine for adults younger than age 64 who need tetanus booster vaccination. A
› Suspect pertussis in a patient who presents with a persistent, paroxysmal cough, with an inspiratory “whoop,” that has lasted for at least
 2 weeks. B
› Prescribe a macrolide antibiotic as a first-line treatment for infants, children, and adults who have pertussis. A

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

Despite a high vaccination rate, pertussis is the only vaccine-preventable disease whose incidence is on the rise.1-3
 The Centers for Disease Control and Prevention (CDC) reported 48,277 laboratory-confirmed cases in 2012—the most since 1955—and 20 pertussis-related deaths.4 And while only 28,639 pertussis cases were reported in 2013, more than 17,000 cases had already been reported through August 15, 2014, suggesting that the incidence may again be on the rise this year.4

This uptick is likely due to a combination of factors, including a growing awareness of pertussis, and therefore a lower threshold for physicians to test for it. In addition, there’s some evidence that the immunity provided by the currently used pertussis vaccines may wane over time. Recently reported epidemics, including those in California this year and in 2010, as well as in Washington in 2011, have added to this concern.5 This article outlines what you can do to improve prevention, diagnosis, and treatment of pertussis.

A 3-stage course of disease

Bordetella pertussis is an aerobic, gram-negative bacterium that causes symptoms by producing multiple antigenic and biologically active components, including pertussis toxin, filamentous hemagglutinin, and agglutinogens. The bacteria adhere to the cilia in the respiratory tract and initiate an inflammatory cascade that paralyzes the cilia and inhibits the respiratory functions responsible for clearing secretions, largely through an immune-mediated response.

Pertussis has an incubation period of approximately 7 days, but this can last as long as 3 to 6 weeks. The 3 stages in the course of the disease are:6

  • Catarrhal. This stage lasts 1 to 2 weeks and is characterized by coryza, sneezing, and a mild, occasional cough.
  • Paroxysmal. This stage lasts 1 to 6 weeks, and is characterized by periods of severe coughing “fits” that include the inspiratory "whoop." These coughing episodes may occur more often at night and may worsen in intensity and frequency in the first 2 to 3 weeks and then gradually decrease. This stage also may include posttussive vomiting.
  • Convalescent. During this stage, the cough begins to wane.

Vaccination: Don’t forget adults

The 2 vaccines used to prevent pertussis are DTaP (diphtheria-tetanus-acellular pertussis) and Tdap (tetanus-diphtheria-acellular pertussis). The difference between the 2 is that the Tdap vaccine contains a reduced dose of the diphtheria and acellular pertussis vaccines. DTaP is designed primarily for children younger than 7 years of age. Tdap is given to older children and adults. The CDC and Advisory Committee on Immunization Practices recommend that children receive 5 doses of DTaP, one dose at each of the following ages: 2, 4, 6, and 15 to 18 months and at 4 to 6 years.7 All adults 19 years of age and older who have not yet received a dose of Tdap should receive a single dose regardless of when they last received any immunization for tetanus or diphtheria.7-10 A one-time Tdap booster should be given to all adults in place of a tetanus booster (TABLE 1).7-10

What about pregnant women? Tdap should be administered to every pregnant woman between 27 to 36 weeks gestation regardless of Tdap history.7,11 This strategy allows maternal antibodies to transfer to the infant, thus providing some protection to the newborn prior to pediatric vaccinations.

All adults ages ≥19 years who have not yet received a dose of Tdap should receive a single dose regardless of when they last received any immunization for tetanus or diphtheria. Is the vaccine becoming less effective? Since 1991, the number of cases of pertussis reported in previously vaccinated adolescents and adults has increased, which suggests waning immunity.12,13 Another recent trial investigating the acellular pertussis vaccine found that immunity decreases dramatically 5 years after the fifth dose.14

Recommendations on who should receive pertussis vaccination have been expanded to include adolescents and adults, including pregnant women and those ages 65 and older in close contact with infants, and this should decrease the overall incidence of disease through decreased communicability.15 Current recommendations call for a single adult vaccination; however, ongoing studies are evaluating whether a booster later in life might be necessary.15

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