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Volume: 24S5 - September 1998

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

Human Campylobacter Cases

Table of Contents

There were 10,320 human cases of Campylobacter infection reported through provincial laboratories to the NLBEP database. This was lower than the number (11,626) reported in 1994. Summary data for 13,680 cases were reported and verified as correct from provincial and territorial public health units to the NND databases. Rates from the NLBEP and NNDS databases by province are presented in  Figure 27. Individual case data were received from seven provinces and one territory, for 13,372 cases. The differences in number of cases between these databases likely reflect the different chains of reporting and within-province protocol for reporting. This is especially evident when laboratory and notifiable diseases rates within each province are compared. The rates are similar for five provinces but differ by a factor of 2 to 4 for the other provinces. The apparent underreporting from some of the provincial laboratories could be due to the privatization of laboratories or the lack of communication between laboratories within the province. Different reporting paths among provinces will also affect the number and type of cases reported. Therefore, variation in reported rates among provinces, as presented in Figure 27, must be interpreted with caution.

Figure 27 Rates of human Campylobacter cases (per 100,000 population) as reported through the National Notifiable Diseases system (upper numbers) and National Laboratory for Bacteriology and Enteric Pathogens (NLBEP) system (lower numbers) by province for 1995

Campylobacter Species Most (98.9%) of the Campylobacter isolates from human cases were C. coli or C. jejuni.  The number of cases reported for most species decreased from 1994 except C. jejuni and C. upsaliensis, which increased (Table 9).

Long-Term Trends The total annual number of Campylobacter cases reported from the NLBEP increased from 1985 to 1995, with fluctuations between 1991 and 1994 (Figure 28). Cases of Campylobacter have been recorded in the NND database since 1996 and show a similar pattern to laboratory Campylobacter cases.

Figure 28
NLBEP and NNDS

1995 Trends

Campylobacter cases showed a seasonal trend, with increased rates in the summertime (Figure 31). British Columbia reported the highest rates and had a prolonged summer peak from May to September. Ontario also reported higher rates than the other provinces.

Figure 31
Cases of Campylobacter 1995
Rate per 100,000 population

Unusual Infections

Campylobacter was isolated from blood in 11 cases (2 cases of C. coli, 5casesof C. fetus ssp fetus and 4 cases of C. jejuni) and from other non-stool sources in five cases (4 cases of C. jejuni and 1 case in which the Campylobacter species was not specified).  

There were 14 cases of  C. fetus (13 ssp fetus and 1 ssp jejuni), five cases of C. lari and 28 C. upsaliensis cases reported in 1995 in the NLBEP database (11, 15 and 14 cases respectively in 1994). C. upsaliensis was predominantly (76%) reported in children < 8 years old but C. fetus and C. lari were predominantly (> 90%)  found in adults. Approximately 45% of the C. fetus ssp fetus were identified from blood isolates.

Hospitalizations and Deaths

From the NND database, there were 291 (120.2/1,000 cases) inpatient and 71 (29.3/1,000 cases) outpatient hospital visits associated with Campylobacter cases in 1995.  Eleven deaths (15.9/1,000 cases) associated with Campylobacter cases were reported. Less than 20% of Campylobacter cases came with information on hospitalization and clinical outcome, so only those cases for which information was provided were used to calculate these rates, which may therefore be biased (see Comparison section).

Outbreaks

There were 36 Campylobacter cases associated with 10 outbreaks recorded in the NLBEP database for 1995. This is lower than the number of cases (58) reported from outbreaks in 1994. Most of the outbreaks (9) were reported to be family associated. The outbreaks were associated with C. jejuni in British Columbia, Saskatchewan and New Brunswick and C. upsaliensis (1) in Saskatchewan. Seventeen cases in British Columbia were found to be associated with drinking lake water, which was confirmed positive for C. jejuni.

In the 1995 NND database, 140 cases were associated with outbreaks, and these were reported from Ontario (58) and British Columbia (82). There is no indicator to link cases with specific outbreaks, but using date, serovar and the first three digits of the postal code, the cases could be grouped into apparent outbreaks. Thus, 39 outbreaks were reported, 27 from Ontario and 12 from British Columbia. Possibly, one of the 39 outbreaks corresponded to one of the 10 outbreaks identified in the NLBEP database for these provinces. This illustrates the underreporting of outbreaks in these databases.

A risk factor was specified for 4% (520) of the Campylobacter cases in the NND database. Of  these, 45% (232) had reported home, 35% (184) had reported travel and 14% (72) had reported restaurant as a risk factor. Other reported risk factors included workplace (10), day care (7), swimming (5), hospital (4), school (4) and institution (2).

Age Distribution

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.

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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