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Diphtheria

Diphtheria is disease that affects primarily the upper respiratory system and is caused by the bacterium Corynebacterium diphtheriae. The bacterium is most commonly spread through person-to-person contact. Diphtheria can be prevented by a vaccine. Canada has included diphtheria in its infant immunization schedule since the 1930's. The success of this program led to a dramatic decline in the number of cases, with very few occurring in Canada since the early 1950s. The National Advisory Committee on Immunization (NACI) recommends immunization against diphtheria.

About Diphtheria

Agent of disease

Diphtheria is caused by the bacterium Corynebacterium diphtheriae.

Symptoms

Some persons infected with diphtheria do not look or feel sick; others develop a sore throat, fever and chills and have difficulty swallowing within 2 to 5 days of becoming infected. This is followed by the formation of a gray, thick membrane at the back of their nose, mouth and/or throat. Complications of the disease include suffocation, paralysis, heart failure, coma and death. One in 10 people with diphtheria die.

Period of communicability

An infected person can transmit diphtheria to others until the bacteria disappear from their discharges or lesions. This usually takes between 2 and 4 weeks with the proper antibiotic treatment. Chronic carriers do exist.

How it is transmitted

The infection is spread by direct contact with an infected individual, as well as by the airborne droplet spread of discharge from the nose or throat of an infected person. Transmission by way of clothing or bedding soiled with nose or throat discharge is rare. Raw milk has also been implicated as a vehicle of transmission.

Worldwide distribution

The number of diphtheria cases is highest during the colder months in temperate zones. In the tropics, seasonal trends are less distinct. In North America, vaccination has greatly reduced the incidence of diphtheria; however, diphtheria was a major problem in countries of the former Soviet Union during the 1990s, with over 150,000 cases and 4500 deaths reported during 1990-1995.

Prevention and control

Diphtheria can be prevented by immunization.

  1. Immunization of all children is recommended at 2, 4, 6 months of age followed by a booster dose at 18 months of age, 4 to 6 years, at 14–16 years of age and then every 10 years (i.e. age 25, 35, 45 years, etc).
  2. Canadians travelling to countries where diphtheria epidemics are occurring should ensure that their vaccination status is up to date

For further information about the immunization, please refer to the most recent version of the Canadian Immunization Guide.

Epidemiology of Diphtheria in Canada

Routine immunization against diphtheria in infancy and childhood has been widely practiced in Canada since 1930. In 1924, there were 9,000 cases reported, the highest annual number recorded in Canada. Moreover, diphtheria was one of the most common causes of death in children from 1 to 5 years of age. By the mid-1950s, routine immunization had resulted in a remarkable decline in the morbidity and mortality of the disease. Toxigenic strains of diphtheria bacilli are detected each year, although classic diphtheria is rare. In Canada, there are 0 to 5 isolates reported each year (see Figure 1 ).

Figure 1. Incidence rates, per 100,000 population, and annual number of cases of diphtheria, Canada, 1924 – 2008.

Figure 1. Incidence rates, per 100,000 population, and annual number of cases of diphtheria, Canada, 1924 – 2008.

Figure 1 - Text Equivalent

Serosurveys of healthy adult populations in Canada indicate that approximately 20% of those surveyed (higher in some age groups) do not have protective levels of antibody to diphtheria. In the former Soviet Union, before the diphtheria outbreak, serologic studies during the 1980s had revealed diphtheria susceptibility rates between 19% and 66% among adults 20 years and older (Dittman et al., 2000).

Diphtheria Surveillance in Canada

In Canada, national surveillance data on diphtheria are collected through the Canadian Notifiable Disease Surveillance System (CNDSS).

Diphtheria Data

The following two tables contain recent data on the number of reported cases and incidence of diphtheria in Canada from 2005 to 20110. Data for 2009 and 2010 to 2011 are preliminary. For further surveillance data, please see the Notifiable Diseases On-Line webpage as well as the Publications section below.

Table 1. Reported cases of diphtheria in Canada by year and age group, 2005 to 20110.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 years or Greater Age Unspecified

*Data obtained from the Canadian Notifiable Disease Surveillance System.
†Preliminary data

2005* 0 0 0 0 0 0 0 0 0 0 0 0
2006* 0 0 0 0 0 0 0 0 0 0 0 0
2007* 4 0 0 0 1 0 0 0 0 2 1 0
2008* 2 1 0 0 0 0 0 0 0 0 1 0
2009 2 0 0 0 1 0 0 0 0 1 0 0
2010 0 0 0 0 0 0 0 0 0 0 0 0
2011 1 0 1 0 0 0 0 0 0 0 0 0
Table 2. Reported incidence per 100,000 population of diphtheria in Canada by year and age group, 2005 to 20110.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 years or Greater

*Data obtained from the Canadian Measles/Rubella Surveillance System.
†Preliminary data

2005* 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
2006* 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
2007* 0.0121 0.0000 0.0000 0.0000 0.0486 0.0000 0.0000 0.0000 0.0000 0.0202 0.0163
2008* 0.0060 0.2701 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0157
2009 0.0059 0.0000 0.0000 0.0000 0.0507 0.0000 0.0000 0.0000 0.0000 0.0099 0.0000
2010 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
2011 0.0029 0.0000 0.0651 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Diphtheria Resources

Case Definitions

Publications

Guidelines and Recommendations

Additional Resources