Staying ahead of pertussis

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Applied Evidence

Staying ahead of pertussis

J Fam Pract. 2014 November;63(11):658-659,666-669

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References

1. Orenstein WA. Pertussis in adults: epidemiology, signs, symptoms, and implications for vaccination. Clin Infect Dis. 1999;28 suppl 2:S147-S150.

2. Tanaka M, Vitek CR, Pascual FB, et al. Trends in pertussis among infants in the United States, 1980-1999. JAMA. 2003;290:2968-2975.

3. Vitek CR, Pascual FB, Baughman AL, et al. Increase in deaths from pertussis among young infants in the United States in the 1990s. Pediatr Infect Dis J. 2003;22:628-634.

4. Centers for Disease Control and Prevention. Pertussis outbreak trends. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc.gov/pertussis/outbreaks/trends.html. Accessed October 10, 2014.

5. Shapiro ED. Acellular vaccines and resurgence of pertussis. JAMA. 2012;308:2149-2150.

6. Centers for Disease Control and Prevention. Pertussis. In: Epidemiology and Prevention of Vaccine-Preventable Diseases. The Pink Book. 2012. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html. Accessed October 10, 2014.

7. Centers for Disease Control and Prevention. Pertussis: Summary of vaccine recommendations. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc.gov/vaccines/vpd-vac/pertussis/recs-summary.htm. Accessed October 10, 2014.

8. Lee GM, Murphy TV, Lett S, et al. Cost effectiveness of pertussis vaccination in adults. Am J Prev Med. 2007;32:186-193.

9. Pertussis vaccines: WHO position paper. Wkly Epidemiol Rec. 2010;85:385-400.

10. Kretsinger K, Broder KR, Cortese MM, et al; Centers for Disease Control and Prevention; Advisory Committee on Immunization Practices; Healthcare Infection Control Practices Advisory Committee. Preventing tetanus, diphtheria, and pertussis among adults: use of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine recommendations of the Advisory Committee on Immunization Practices (ACIP) and recommendation of ACIP, supported by the Healthcare Infection Control Practices Advisory Committee (HICPAC), for use of Tdap among healthcare personnel. MMWR Recomm Rep. 2006;55(RR-17):1-37.

11. English P. Pertussis vaccination in pregnant women will protect neonates. Practitioner. 2012;256:5.

12. Winter K, Harriman K, Zipprich J, et al. California pertussis epidemic, 2010. J Pediatr. 2012;161:1091-1096.

13. Centers for Disease Control and Prevention (CDC). Pertussis epidemic—Washington, 2012. MMWR Morb Mortal Wkly Rep. 2012;61:517-522.

14. Klein NP, Bartlett J, Rowhani-Rahbar A, et al. Waning protection after fifth dose of acellular pertussis vaccine in children. N Engl J Med. 2012;367:1012-1019.

15. Centers for Disease Control and Prevention (CDC). Updated recommendations for use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine in adults aged 65 years and older - Advisory Committee on Immunization Practices (ACIP), 2012. MMWR Morb Mortal Wkly Rep. 2012;61:468-470.

16. Cherry JD, Tan T, Wirsing von Konig C, et al. Clinical definitions of pertussis: Summary of a global pertussis initiative roundtable meeting, February 2011. Clin Infect Dis. 2012;54:1756-1764.

17. Zouari A, Smaoui H, Kechrid A. The diagnosis of pertussis: which method to choose?. Crit Rev Microbiol. 2012;38:111-121.

18. Loeffelholz MJ, Thompson CJ, Long KS, et al. Comparison of PCR, culture, and direct fluorescent-antibody testing for detection of Bordetella pertussis. J Clin Microbiol. 1999;37:2872-2876.

19. Tozzi A, Celentano L, Ciofi degli Atti ML, et al. Diagnosis and management of pertussis. CMAJ. 2005;172:509-515.

20.  von König CH, Halperin S, Riffelmann M, et al. Pertussis of adults and infants. Lancet Infect Dis. 2002;2:744-750.

21. Cattaneo LA, Edwards KM. Bordetella pertussis (whooping cough). Semin Pediatr Infect Dis. 1995;6:107-117.

22. Hoppe JE, Eichhorn A. Activity of new macrolides against Bordetella pertussis and Bordetella parapertussis. Eur J Clin Microbiol Infect Dis. 1989;8:653-654.

23. Bass JW. Erythromycin for treatment and prevention of pertussis. Pediatr Infect Dis. 1986;5:154-157.

24. Health Protection Surveillance Centre. Guidelines for the Public Health Management of Pertussis: Public Health Medicine Communicable Disease Group HSE—October 2013. Health Protection Surveillance Centre Web site. Available at: http://www.hpsc.ie/A-Z/VaccinePreventable/PertussisWhoopingCough/InformationforHealthcareWorkers/File,13577,en.pdf. Accessed October 2, 2014.

25. Dodhia H, Miller E. Review of the evidence for the use of erythromycin in the management of persons exposed to pertussis. Epidemiol Infect. 1998;120:143-149.

26. Altunaiji S, Kukuruzovic R, Curtis N, et al. Antibiotics for whooping cough (pertussis). Cochrane Database Syst Rev. 2007;(3):CD004404.

27. Prophylactic erythromycin for whooping-cough contacts. Lancet. 1981;1:772.

28. Halperin SA, Bortolussi R, Langley JM, et al. A randomized, placebo-controlled trial of erythromycin estolate chemoprophylaxis for household contacts of children with culture-positive bordetella pertussis infection. Pediatrics. 1999;104:e42.

29. Langley JM, Halperin SA, Boucher FD, et al; Pediatric Investigators Collaborative Network on Infections in Canada (PICNIC). Azithromycin is as effective as and better tolerated than erythromycin estolate for the treatment of pertussis. Pediatrics. 2004;114:e96-e101.

30. Tiwari T, Murphy TV, Moran J; National Immunization Program, CDC. Recommended antimicrobial agents for the treatment and postexposure prophylaxis of pertussis: 2005 CDC Guidelines. MMWR Recomm Rep. 2005;54(RR-14):1-16.

Diagnosis needs to be  confirmed by lab testing 

Any patient who reports having a persistent cough should be considered for pertussis testing and treatment, and any clinician who triages such patients should ask detailed questions about the characteristics and duration of the patient’s symptoms. Antibiotics do not appear  to shorten the duration of pertussis symptoms unless given  in the catarrhal phase. However, while a prolonged cough is the hallmark of pertussis, there are many other potential causes of this symptom. Therefore, diagnosis of pertussis requires a combination of clinical and laboratory testing, because clinical parameters alone are neither sensitive nor specific enough for pertussis infection.

TABLE 2¹⁶outlines the clinical and laboratory diagnostic criteria for pertussis from the CDC and the World Health Organization. Suspect pertussis in a patient who’s had a cough for more than 14 days that includes an inspiratory “whoop.” In infants, pertussis should be suspected in those with symptoms that suggest cough and associated apnea.¹⁶Order laboratory testing for any patients who have clinical signs or symptoms of pertussis.

Four methods of lab testing for pertussis infection are polymerase chain reaction (PCR), direct fluorescent antibody (DFA) testing, serologic testing, and culture (TABLE 3).^17-19The sensitivity of these tests is as follows: PCR, 90% to 95%; DFA, 50% to 60%; serologic testing, 70% to 80%; and culture, 50% to 70%. The specificity is: PCR, 95% to 98%; DFA, 90% to 100%; serologic testing, 90% to 100%; and culture, 100%.

PCR is the preferred method because of its rapid turnaround and fairly high sensitivity. The reliability of PCR decreases, however, for a patient who’s had a cough for more than 2 weeks because the individual may have transitioned to the convalescent phase, when less bacterial DNA remain.

Results from DFA testing also are rapidly available, but the need for specialized equipment and a well-trained examiner of the specimen limits widespread use of this test. It also is not particularly sensitive for pertussis.

Serologic testing is less reliable in patients who have received an acellular pertussis vaccine and is not helpful in the first few weeks of infection.

The sensitivity of culture is best if the sample is collected appropriately (more on this in a bit) and within the first 2 weeks of symptoms (catarrhal stage). Culture is also very specific.

Given the strengths and weakness of the different tests, an acceptable method of laboratory confirmation is to obtain PCR and/or culture within the first 2 weeks of symptoms in all age groups.^17-20Testing after 2 weeks should include a combination of PCR and serology.¹⁷It is essential that the clinical specimen used for PCR or culture testing for pertussis is properly collected. (See “Collecting a swab for pertussis testing” below.²¹)

Collecting a swab for pertussis testing

The illustration below shows the correct swab and sampling method. Swab tips may be polyester (such as Dacron or rayon) or they may be nylon-flocked. Cotton-tipped or calcium alginate swabs are not acceptable because the residue will inhibit DNA assays.²¹ The specimen must be obtained from the posterior nasopharynx and not the nares or oropharynx. The Centers for Disease Control and Prevention offers a video that demonstrates how to properly collect a specimen for testing at http://www.cdc.gov/pertussis/clinical/diagnostic-testing/specimen-collection.html.

Tx is effective when started early

Antibiotics are an effective treatment for pertussis, but they need to be started within the first few weeks of developing symptoms. Studies have not found evidence that antibiotics shorten the duration of pertussis symptoms unless they are given in the catarrhal phase.^22,23It can be challenging to get treatment started during this window, however, because patients may put off seeking care for symptoms they perceive as only minor, such as a cough, until the disease progresses. In addition, physicians may not suspect pertussis in patients who present with a cough they have had for only a short time, and therefore may not test for it.

It may be necessary to rely on clinical suspicion when deciding whether to initiate treatment for pertussis before testing to confirm the diagnosis. For patients in whom clinical suspicion of pertussis is high and who may be in contact with high-risk individuals, it may be acceptable to begin treatment before receiving lab test results.^24,25A recent Cochrane meta-analysis²⁶recommended initiating treatment to render a patient who has pertussis “noninfectious” but without an expectation of diminishing symptoms.

Limited role for prophylaxis. There is little evidence that prophylactic treatment for pertussis can decrease the spread of the disease. Studies that investigated potential benefits of prophylactic treatment for pertussis have been inconclusive, except for individuals who are in close contact with an infant younger than 6 months of age who has not been fully immunized.^27,28