[Table of Contents]

Volume: 24S5 - September 1998

Canadian Integrated Surveillance Report for 1995 on Salmonella,
Campylobacter and Pathogenic Escherichia coli

Comparison of Campylobacter, Salmonella and E. coli Human Cases

Table of Contents

The most frequently reported of the three notifiable enteric pathogens described in this report was Campylobacter (13,680 cases) followed by Salmonella (6,389 cases) and Escherichia coli (1,493 cases).

Seasonal and Geographic Distributions

Cases of Campylobacter infection were most common in the summertime and had a fairly even distribution geographically  (Figure 31). Salmonella cases showed a moderate summertime association, with the exception of winter peaks in the territories,  and were distributed throughout Canada (Figure 32). The incidence of pathogenic E. coli showed a distinct summertime peak with increased rates in central to western Canada and Prince Edward Island (Figure 33).

Figure 31
Cases of Campylobacter 1995 Rate per 100,000 population Data from Notifiable Diseases Summary database

Figure 32
Cases of Salmonella 1995 Rate per 100,000 population Data from Notifiable Diseases Summary database

Figure 33
Cases of Pathogenic E. coli 1995 Rate per 100,000 population *per 200,000 for PEI Data from Notifiable Diseases Summary database

Long-Term Trends

The number of cases reported annually in the NLBEP database increased from the mid- to late 1980s  for all three pathogens (Figure 34). From the early 1990s to 1995 the annual number of Campylobacter cases continued to increase, and the number of Salmonella and E. coli cases showed a moderate decrease.

Figure 34
Data from NLBEP

Risk Factors Reported

The most commonly reported risk factors for infections with these three pathogens were episodes of travel, home related risk factors and having eaten at a restaurant (Figure 35). In Salmonella and Campylobacter cases the most commonly reported risk factors were home and travel whereas home and restaurant were reported most often as risk factors for E. coli cases. Day care was reported as a risk factor in a higher proportion of E. coli cases than Salmonella or Campylobacter cases. These rates may be biased, as risk factors were reported for less than 14%  of the cases.

Figure 35
Rates of risk factors per 1,000 cases Notifiable Diseases - Individual case data

Hospitalizations and Deaths

The reported numbers of Campylobacter and Salmonella cases requiring hospitalization were only slightly higher than the E. coli cases (Table 11). On the basis of the cases for which hospitalization information was provided, pathogenic E. coli cases showed a hospitalization rate that was approximately 3 times that of Campylobacter cases and 1.5 times that of Salmonella cases. The estimated case fatality rate for pathogenic E. coli was 2.5 times that of Campylobacter and about 15% higher than that of Salmonella cases. In less than 20% of cases was information on hospitalization and outcome available, and only those cases for which information was provided were used to calculate these rates. Therefore these rates may be biased.

Age Distributions

The age distribution of cases reported to the NND Individual Cases database for each of these three pathogens showed a peak in children < 2 years of age, which extended to about 10 years of age (Figure 36). Campylobacter and Salmonella cases showed smaller secondary peaks in the 20-35-year-old age range, but no such peak was observed for E. coli cases.

Figure 36
Number of cases by age in 1995

Data from Notifiable Diseases Summary database

The lower number of verotoxigenic E. coli and Campylobacter cases in the < 1-year-old children compared with 1-year olds is at least partially due to the fact that babies born in 1995 were at risk for only half the year, on average. This suggests that risk of salmonellosis is much higher for children < 1-year old than for 1-year olds.

The proportion of cases < 1 year of age was higher for Salmonella (8%) than for E. coli (4%) and Campylobacter (2%). However, the proportion of cases < 10 years of age was higher for E. coli (40%) than for Salmonella (32%) and Campylobacter (20%).

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