ARCHIVED - Canadian Integrated Surveillance Report: Salmonella, Campylobacter, verotoxigenic E. coli and Shigella, from 2000 to 2004

Human Campylobacter Cases

The number of Campylobacter cases reported to the NDRS declined between 2000 and 2004 (Table 15). Although Campylobacter numbers reported to the NESP were considerably lower over the fiveyear period, a similar trend was observed in NDRS. The difference between the NDRS and NESP data reflect the low frequency with which Campylobacter isolates are sent or reported from local laboratories to the provincial laboratories. NESP assesses Campylobacter isolate data under the assumption that the isolate and data flow are consistent over time in each province.

Campylobacter rates derived from the NDRS and the NESP databases are shown in Figure 24. The difference between the two databases was most apparent in British Columbia, Ontario, Québec, and Alberta. For all provinces and territories, with the exception of the Yukon and Nunavut, a decline in the rate was observed between 2000 and 2004 according to the NDRS data. The four provinces with the largest populations also had the highest rates, with British Columbia reporting a rate above 60 per 100,000 population in 2000 (NDRS).

Figure 24: Rates of campylobacteriosis (per 100,000 population) as reported to the National Notifiable Disease
Summary program (NDRS) and the National Enteric Surveillance Program (NESP) by province/territory, 2000 to 2004

Campylobacter Species

The number of cases by Campylobacter species reported to the NESP is listed in Table 16. The most prevalent species reported between 2000 and 2004 was C. jejuni. The ratio of C. jejuni to C. coli was approximately 6:1.

Long-term Trends

According to the NDRS data, the rate of campylobacteriosis declined between 1995 and 2004 (Figure 25). The rate of Campylobacter infections reported to the NESP was relatively constant from 1998 to 2004, leading to a fairly consistent 7-fold difference between the two databases. As noted above, the lower rates recorded by the NESP reflect the low frequency with which Campylobacter isolates are sent or reported to most of the provincial laboratories.

Figure 25: Rates of Campylobacter cases (per 100,000 population), 1995 to 2004, NDRS and NESP

Monthly and Provincial/Territorial Trends

The frequency of Campylobacter infections reported through the NDRS by month is shown in Figure 26. Clear and progressively smaller summer peaks were observed between 2000 and 2004. Overall the lowest monthly numbers reported were in February and March. The seasonal variation in Campylobacter rates (combined over the five-year period) by province/territory is shown in Figure 27. Similar seasonal patterns were observed for most provinces/territories, with the summer season having the majority of cases reported, except in the Yukon and Prince Edward Island.

Figure 26: Reported cases of Campylobacter by month, 2000 to 2004, NDRS

Very few outbreaks or case clusters related to Campylobacter were recorded during this five-year period. In 2000, 116 Campylobacter infections were confirmed among residents of Walkerton, Ontario and were associated with a community-wide outbreak of E. coli O157:H7 and Campylobacter infections linked to the contaminated municipal water supply⁽¹⁷⁾. In 2004, 40 cases of C. coli infection reported by British Columbia were associated with a deli counter at a grocery store.

Figure 27: Average reported rate of Campylobacter cases (per 100,000 population per season*) by province/territory, 2000 to 2004, NDRS

*Winter includes December, January and February; Spring includes March, April and May; Summer includes June, July and August; Fall includes September, October and November.

Age and Gender Distribution

The rate of Campylobacter infection by age group is shown in Figure 28. The highest rate was observed in infants and young children, followed by adults in their 20s.

Figure 28: Reported rate of Campylobacter cases (per 100,000 population) by age group, 2000 to 2004 combined, NDRS

The average rate of Campylobacter infection was consistently higher among males over the five-year period (males: 38.96 per 100,000 population; females, 32.13 per 100,000 population). This trend is supported by findings reported in a study investigating the risk factors for Campylobacter infection in the United States (18).

Exposure Settings for Outbreaks and Case Clusters

There were 11 outbreaks and case clusters related to Campylobacter and 177 outbreak-related laboratory-confirmed cases reported to the NML and NESP between 2000 and 2004. There were 116 confirmed cases of Campylobacter sp. that were associated with the E.coli O157:H7 outbreak in Walkerton, Ontario in 2000. The low number of outbreaks, case clusters and outbreak-related case counts is consistent with the considerable under-reporting of Campylobacter to the NESP, as well as the lack of an easily available and widely accepted typing scheme. Outbreaks and case clusters by exposure setting are shown in Table 17. Household settings represented the largest number of reported Campylobacter outbreaks, while one food service outbreak, linked to a deli counter at a local grocery store (40 cases) showed the highest outbreak related case counts among all other settings (excluding the Walkerton, Ontario outbreak).

* 116 confirmed cases of Campylobacter sp. were associated with the E. coli O157:H7 outbreak in Walkerton, Ontario

Travel-acquired Infections

Between 2000 and 2004, 67 travel-acquired cases of Campylobacter were reported to the NESP.A history of travel was provided for approximately 1% of all Campylobacter infections reported to the NESP. Travel to Asia, Mexico and the Caribbean accounted for the majority of these infections (Table 18).