[Table of Contents]

Volume: 24S3 - July 1998

Guidelines for the Control of Diphtheria in Canada

INTRODUCTION

Before the 1940s, diphtheria was recognized as a major cause of childhood morbidity and mortality in many industrialized countries. It has been estimated that in temperate zones more than one in 20 persons suffered from clinical diphtheria during their lifetimes, with a case fatality rate of 5% to 10%⁽¹⁾. The introduction of widespread immunization with diphtheria toxoid in industrialized countries in the 1940s and 1950s was followed by a marked decrease in the incidence of diphtheria and its virtual elimination in some countries. In Canada, where the diphtheria toxoid was introduced for use in 1926, routine immunization of infants and children since 1930 has led to similar substantial declines in diphtheria morbidity and mortality.

However, in this decade, diphtheria has re-emerged as a significant disease threat for many industrialized countries despite their long-standing control of the disease. In particular, the resurgence of epidemic diphtheria in the Newly Independent States (NIS) of Eastern Europe in 1990 and its subsequent importation to other European countries has raised awareness about the threat of re-emerging diphtheria. Approximately 125,000 cases and 4,000 deaths were reported from the NIS from 1990 to 1995. Despite an extremely low risk of indigenously acquired diphtheria in Canada at present, the potential for importation cannot be overlooked. Rapid clinical and public-health responses would be required to avert transmission of diphtheria in Canada if importation were to occur, particularly in (highly unlikely but plausible) high-risk situations, such as multiple simultaneous carriage of toxigenic strains by a group of travellers from an endemic region to a localized area or community. This document presents background information on diphtheria, including the current epidemiologic situation in Canada; strategies for diphtheria control; and guidelines for the management of cases and contacts.

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