Pertussis control in Canada

Scott A. Halperin

The outbreak of pertussis in a refinery as described by John Hoey in a recent article on pertussis in adults1 is interesting but pales in comparison with outbreaks recently reported from Vancouver Island, where well over 100 positive cases (by both culture and polymerase chain reaction) were diagnosed in adolescents and adults,2 and from Quebec, where the severity of pertussis in older adults was well characterized.3 Rarely, pertussis can lead to severe complications, even in a healthy adult.4

The case-fatality rate of 0.8% reported by Hoey actually represents cases in infants under 2 years of age admitted to hospital.5 The overall case fatality rate is unknown but is undoubtedly lower.

There are a number of differences between the United States and Canada in recommendations for treatment and chemoprophylaxis of pertussis contacts. In Canada, treatment and chemoprophylaxis with erythromycin are recommended for 10 days rather than 14, and the maximum daily dose is 1 g rather than 2 g.6 Also, chemoprophylaxis is recommended in this country only in households or other environments where there is an infant under 1 year of age. Canadian guidelines will soon be revised according to the recommendations of the National Consensus Conference on Pertussis (held in May 2002). On the basis of results from 4 randomized controlled trials, the recommended treatment for pertussis will be 7 days of erythromycin,7 5 days of azithromycin8 or 7 days of clarithromycin,9 and chemoprophylaxis will be limited to households with an infant under 1 year of age (because of lack of benefit in modifying the development of clinical disease in contacts10).

The recommendations for vaccination presented by Hoey were those of the US Centers for Disease Control and Prevention. In Canada, an adolescent/adult formulation of acellular pertussis vaccine combined with diphtheria and tetanus toxoids (known by the abbreviation TdaP; Adacel, Aventis Pasteur) is licensed for use in people 12 to 50 years of age. The National Advisory Committee on Immunization recommends that all adolescents receive TdaP in place of Td.11 More extensive use of this vaccine beyond adolescence may be beneficial in controlling the increasing burden of disease in adults.

Scott A. Halperin Head, Pediatric Infectious Diseases Dalhousie University IWK Health Centre Halifax, NS

References

1.↵
Hoey J. Pertussis in adults. CMAJ 2003;168 (4): 453-4.
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2.↵
Skowronski DM, De Serres G, MacDonald D, Wu W, Shaw C, Macnabb J, et al. The changing age and seasonal profile of pertussis in Canada. J Infect Dis 2002;185:1448–53.
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3.↵
De Serres G, Shadmani R, Duval B, Boulianne N, Déry P, Fradet MD, et al. Morbidity of pertussis in adolescents and adults. J Infect Dis 2000; 182: 174–9.
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4.↵
Skowronski DM, Buxton JA, Hestrin M, Keyes RD, Lynch K, Halperin SA. Carotid artery dissection as a possible severe complication of pertussis in an adult: clinical case report and review. Clin Infect Dis 2003;36:e1–4.
5.↵
Halperin SA, Wang EL, Law B, Mills E, Morris R, Déry P, et al. Epidemiological features of pertussis in hospitalized patients in Canada, 1991–1997: report of the Immunization Monitoring Program–Active (IMPACT). Clin Infect Dis 1999;28:1238–43.
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6.↵
National Advisory Committee on Immunization, Advisory Committee on Epidemiology, and Canadian Paediatric Society. Statement on management of persons exposed to pertussis and pertussis outbreak control. Can Commun Dis Rep 1994; 20: 193-9.
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7.↵
Halperin SA, Bortolussi R, Langley J, Miller B, Eastwood B. Seven days of erythromycin estolate is as effective as fourteen days for the treatment of Bordetella pertussis infections. Pediatrics 1997; 100:65–71.
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8.↵
Halperin SA, Langley JM, Boucher FD, Smith B. Azithromycin is as effective as and better tolerated than erythromycin estolate for the treatment of pertussis [abstract 169]. 40th annual meeting of Infectious Diseases Society of America; 2002 Oct 24–27; Chicago.
9.↵
Lebel MH, Mehra S. Efficacy and safety of clarithromycin versus erythromycin for the treatment of pertussis: a prospective, randomized, single blind trial. Pediatr Infect Dis J 2001;20: 1149-54.
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10.↵
Halperin SA, Bortolussi R, Langley JM, Eastwood BJ, De Serres G. A randomized, placebo-controlled trial of erythromycin estolate chemoprophylaxis for household contacts of children with culture-positive Bordetella pertussis infection. Pediatrics 1999;104(4):e42. Available: www.pediatrics.org/cgi/content/full/104/4/e42 (accessed 2003 Apr 9).
11.↵
National Advisory Committee on Pertussis. Pertussis. In: Canadian immunization guide. 6th ed. Ottawa: Canadian Medical Association; 2002. p. 169-76.