Pertussis: A Reemerging Threat
Article Outline
- Abstract
- Reemergence of a Life-Threatening Disease
- A Frequently Missed Diagnosis
- Treatment
- Recent Vaccine Developments
- Conclusion
- References
- Copyright
Abstract
Pertussis, commonly known as whooping cough, is associated with high rates of morbidity and mortality in infants. Immunity to the childhood pertussis vaccine wanes over time. This creates reservoirs for disease among susceptible adults. Adult caregivers and health care workers can transmit pertussis to those infants and children not fully immunized. Two new vaccines are available for adolescents and adults to protect these age groups from pertussis and thus avoid transmission to infants. Pertussis rates in the United States are increasing dramatically. This disease can present a diagnostic dilemma to providers not accustomed to seeing this infection. Providers can now encourage older patients to receive these newly formulated vaccines and prevent the further spread of pertussis.
Keywords: immunity , pertussis , Tdap , vaccine
Melenda S. is a 20-year-old undergraduate nursing student who presents to your college health clinic complaining of a persistent cough. She has been coughing for more than 3 weeks. Her cough is shallow and dry and is characterized by repeated spasms of coughing, often initiated by deep breathing or other mild stimulation. She previously presented to your health center 2 weeks ago, after about a week of cough, low-grade fever, and coryza-like symptoms. A rapid strep test was negative. She was diagnosed with pharyngitis and because of her fever was placed on amoxicillin. Melenda states she is feeling better, but now complains that her cough is not improving and “sometimes I cough until I throw up.” Melenda is completing a 7-week pediatric rotation in a local hospital.
Physical examination reveals a nontoxic-appearing young adult. Vital signs include a temperature of 98.7°F, pulse of 92, respirations of 20, and blood pressure of 116/72 mm Hg. Tympanic membranes are somewhat injected. Oropharynx appears slightly reddened. There is minimal cervical lymphadenopathy. Chest is clear to auscultation, but the patient does indeed exhibit a rapid-fire, dry, recurring cough during the examination. The examination is otherwise unremarkable.
What will you include in your differential diagnosis?
Reemergence of a Life-Threatening Disease
Pertussis, commonly known as whooping cough, has always been associated with high morbidity and mortality, particularly in infants. The disease is caused by a gram-negative coccobacillus, Bordatella pertussis, that colonizes the respiratory tract. Classic symptoms include fever and malaise followed by paroxysmal coughing episodes that leave the infected person gasping for breath with a characteristic “whoop” followed by another coughing spasm.
Adults who contract pertussis typically experience a flulike illness followed by a protracted cough. However, complications in infants and young children can include hypoxia, apnea, pneumonia, seizure, and encephalopathy. In 2003, 13 children died of pertussis in the United States.1 Worldwide, pertussis is still a leading cause of vaccine-preventable deaths, with about 300,000 total fatalities in 2000.2 How could this happen when a pertussis vaccine has been in use since the 1940s?
Active immunity incurred from a vaccine should not be considered permanent. The duration of the protection conferred by the diphtheria, tetanus, and acellular pertussis (DTaP) vaccine commonly used is thought to be approximately 5 to 10 years.3 The whole-cell pertussis vaccine previously in use conferred immunity for about 10 to 12 years.4 Although whole-cell vaccines did confer longer immunity, they were associated with more severe adverse events and were replaced with acellular vaccines for pertussis in 1996.
The 2006 Childhood Immunization Schedule5 defines the interval for childhood pertussis immunization. According to this schedule, infants should receive an immunization containing the acellular pertussis toxoid at 2, 4, and 6 months of age. Following this, a fourth dose is given at age 15 to 18 months and a final dose at 4 to 6 years of age. Until recently, no routine recommendations for pertussis vaccine existed for persons 7 years or older.
Recognition of the temporary immunity conferred by vaccines is one of the factors that led to the recent development of pertussis vaccines for the adult population. As the immunity conferred by the childhood pertussis vaccine wanes, adolescents and adults again become susceptible to pertussis. Using the expected length of immunity described earlier, it can be expected that immunized children again become susceptible to pertussis infection between the ages of 12 and 17 years.
Illness caused by pertussis in adolescents and adults causes significant loss of school and work time. The incidence of pertussis has been increasing dramatically in the United States since the 1980s. It is estimated that there are now between 800,000 and 3.3 million cases of pertussis each year.6 One researcher suggested that 0.5% of adults in the United States have symptomatic pertussis annually.7
Adolescents and adults tend to exhibit milder symptoms of pertussis than infants (Table 1). However, the greatest danger of pertussis lies in the transmission of the bacterium from infected adults to susceptible infants, either in infants too young to start the vaccine series or before full immunity is conferred. Pertussis is highly contagious, and young children are more susceptible to the serious complications of this disease, which can include pneumonia, seizures, encephalopathy, and permanent brain damage.4 Most young infants diagnosed with pertussis must be hospitalized because of the serious expressions of the disease in this age group.
Table 1. Pertussis Presentation: Adults and Children
| Adults and Teens | Infants and Young Children |
|---|---|
| Characterized by persistent cough (>7 d) | Paroxysmal coughing with average 15 attacks in 24 h |
| Inspiratory whoop uncommon | High-pitched inspiratory whoop following paroxysmal cough |
| May present as common respiratory infection | Children often vomit and become exhausted |
| Disease often milder than in young children | Patient appears very ill and distressed |
A Frequently Missed Diagnosis
Pertussis is diagnosed by a culture of nasal secretions, generally by using a Dacron-tipped swab and solid culture medium. In diagnosing pertussis, several barriers must be overcome. The first and most important barrier is the failure of the provider to consider pertussis in the differential diagnosis. Often, only when a violent and persistent cough brings an adult patient back to the office is pertussis then considered a possibility.
When the provider fails to consider the possibility of pertussis, a patient may be placed on antibiotic therapy for another suspected condition. This results in a missed opportunity to obtain a sample of the organism, which can usually be collected from the upper respiratory tract only during the initial 10-day period of colonization.8
Problems with culture technique present a second diagnostic barrier. The technique used to collect the specimen may by inadequate to capture enough bacteria for the culture. Underdiagnosis also occurs because sensitivity of cultures can be 40% or less.9
Finally, laboratory staff unfamiliar with the procedure may not process the specimen correctly. Information specific to collection of pertussis cultures is available through hospital laboratories and state health departments.
Pertussis is included in the list of diseases reportable to public health agencies. As such, disease rates are tracked within each state. Rates of cases with culture-positive pertussis differ sharply across state lines, undoubtedly reflecting a difference in recognition of pertussis as a possibility in the differential diagnosis, rather than actual differences in disease incidence.10 Outbreaks of pertussis tend to run in 2- to 5-year cycles with peaks in the number of cases reported.
Treatment
Pertussis disease involves two stages. During the catarrhal stage, an adult experiences about a 10-day period of fever, malaise, and cough. During this phase, antibiotics can reduce the severity and duration of the disease. The second, or toxemic, phase starts gradually with a prolonged cough, often occurring in paroxysms, caused by toxins released by the B pertussis bacteria. It is at this stage that children, but generally not adults, exhibit the characteristic whoop. At this stage, antibiotics will not affect the course of the disease and the bacterium generally cannot be recovered and cultured from the patient.8 The duration of pertussis symptoms may be as long as 6 to 10 weeks.
Several antibiotics are effective against pertussis (Table 2). Erythromycin is considered first-line therapy, but it is not always selected because of the incidence of gastrointestinal side effects. Trimethoprim-sulfamethoxazole, azithromycin, and clarithromycin are also effective.3 However, if initiated after the catarrhal phase of the illness, antibiotics will not affect the cough caused by the toxins.
Table 2. Pertussis Treatment Recommendations for Adults
| Antimicrobial Agent | Dose |
|---|---|
| Azithromycin | 500 mg qd ×1 day, then 250 mg qd × 4 days |
| Erythromycin | 500 mg qid × 14 days |
| Clarithromycin | 500 mg bid × 7 days |
| TMP-SMZ | 180/800 mg bid × 14 days |
Recent Vaccine Developments
In November 2005, the Advisory Committee on Immunization Practices (ACIP) recommended that adults aged 19 to 64 years be vaccinated with the newly licensed adult booster for tetanus, diphtheria, and pertussis (Tdap)11 (Table 3). The adult Tdap vaccine is intended to replace the current tetanus and diphtheria (Td) vaccine currently used as the adult booster vaccine.
Table 3. Available Diphtheria, Tetanus, and Acellular Pertussis Vaccines by Age Group
| Age | Product | Manufacturer | Components |
|---|---|---|---|
| Childhood | Daptacel (6 wk-6 y) | Sanofi pasteur | Diphtheria and tetanus toxoids, plus 4 pertussis antigens |
| Infanrix (6 wk-6 y) | GlaxoSmithKline | Diphtheria and tetanus toxoids, plus 3 pertussis antigens | |
| Tripedia (6 wk-6 y) | Sanofi pasteur | Diphtheria and tetanus toxoids, plus 2 pertussis antigens | |
| Adolescence | Boostrix (10-18 y) | GlaxoSmithKline | Diphtheria and tetanus toxoids, plus 3 pertussis antigens |
| Adolescent/Adult | Adacel (11-64 y) | Sanofi pasteur | Diphtheria and tetanus toxoids, plus 4 pertussis antigens |
Notably, ACIP has also voted to recommend Tdap vaccination for new mothers and those adolescents and adults who are in close contact with infants. Adolescents should be vaccinated with Tdap at age 11 to 12 years. This recommendation currently applies to those adolescents who have not recently received a tetanus and diphtheria (Td) booster. Adolescents aged 13 to 18 years who missed the Tdap booster at age 11 to 12 years should also get a booster dose of Tdap to add pertussis protection.12 Tdap can be given to adolescents at the same time as the meningococcal vaccine but not in the same site. For subsequent Tdap boosters, routine recommendations include substituting each Td booster with a Tdap booster at any time a booster dose is indicated. Routine boosters are recommended every 10 years throughout adulthood.
Two brands of Tdap vaccines for adolescents and adults are currently marketed. The manufacturer of the adult vaccine, sanofi pasteur, markets the vaccine under the trade name Adacel. This product has received an indication from the Food and Drug Administration (FDA) for use in adolescents aged 11 to 18 years as well as adults aged 19 to 64 years. In addition, an adolescent Tdap vaccine manufactured by GlaxoSmithKline and marketed as Boostrix has been approved for use in adolescents aged 10 to 18 years. These are the first pertussis vaccines licensed for adolescents and adults.
These vaccines are well tolerated. Adacel compared favorably with Td vaccine in a trial of adolescents and adults to assess adverse events.13 Events most frequently reported included mild pain and localized redness and swelling. The most common systemic reactions were transient headache and fatigue. Both products require refrigeration and are administered as a 0.5-mL injection in the deltoid muscle.14
These vaccines do not appear on the current schedule of adolescent and adult immunizations,15 but they are referenced in the vaccine guidelines included with the schedule.
Conclusion
Several new developments have heightened the awareness of this growing immunization need. Nosocomial pertussis outbreaks have recently been reported.16 These outbreaks have included adult health care workers infected by infants admitted for pertussis disease. In February 2006, health care workers were added as an emphasis to the list of persons recommended to receive the Tdap booster in place of a Td booster. This recommendation is intended to potentially help prevent the spread of the disease to other vulnerable infants.
In addition, there were recent reports of variants of the pertussis toxins not covered by the pertussis vaccine.10 These and other emerging problems related to the spread of this potentially deadly disease make it even more important that providers consider pertussis in the differential diagnosis of patients with upper respiratory symptoms. Finally, providers should undertake patient education campaigns to heighten awareness of adolescent and adult vaccine availability and encourage these patients to seek initial and ongoing immunization for pertussis. By encouraging Tdap booster immunization for adolescents and adults, providers will curtail the reemergence and spread of pertussis in the United States.
References
- . Disease listing: pertussis . Atlanta, Ga: Centers for Disease Control; October 13, 2005;
- World Health Organization, Department of Vaccines and Biologicals. Pertussis surveillance: a global meeting. World Health Organization. Proceedings of meeting, Geneva, 2001.
- . Childhood malady makes grown-up return . Clin Advisor . 2004;3:61–66
- . Routine childhood vaccines, 2005 . J Fam Pract . 2005;3(special issue):S5–S6
- . Recommended childhood immunization schedule: United States . Atlanta, Ga: Centers for Disease Control; October 2005–September 2006; Available at: www.cdc.gov. Accessed June 26, 2006.
- . The epidemiology of pertussis . Pediatrics. . 2005;115(5):1422–1427
- Efficacy of an acellular pertussis vaccine among adolescents and adults . N Engl J Med. . 2005;353(15):1555–1563
- . Todar's online textbook of bacteriology. University of Wisconsin-Madison Department of Bacteriology . Available at: http://textbookofbacteriology.net/pertussis.html Accessed June 26, 2006.
- . Whooping cough, a continuing problem [editorial] . BMJ . 2002;324(7353):1537–1538
- . MMWR Morb Mortal Wkly Rep. . 2005;54(31):770
- Recommendation for adult vaccination with new tetanus, diphtheria, and pertussis vaccine (Tdap) [press release] . Atlanta, Ga: Centers for Disease Control, Advisory Committee on Immunization Practices; November 9, 2005;
- . ACIP recommends adolescent vaccination for tetanus, diphtheria, and pertussis vaccine . Available at: www.cdc.gov.nip/pr/pr_tdap_jun2005.htm June 30, 2005; Accessed June 28, 2006.
- Adacel prescribing information. sanofi pasteur, 2005.
- . Tetanus, diphtheria, acellular pertussis booster vaccination for adolescents . Pediatr Pharmacol . 2005;11(7): (New York) Available at: www.medscape.com Accessed June 28, 2006.
- . Recommended adult immunization schedule: United States, October 2005—September 2006 . MMWR QuickGuide Wkly. . 2005;54(40):1–4
- . Nosocomial pertussis: costs of an outbreak and benefits of vaccinating health care workers . Clin Infect Dis. . 2006;42(7):981–988
PII: S1555-4155(06)00674-X
doi:10.1016/j.nurpra.2006.09.001
© 2007 American College of Nurse Practitioners. Published by Elsevier Inc. All rights reserved.
