Physician diagnostic and reporting practices for gastrointestinal illnesses in three health regions of British Columbia.

OBJECTIVES: To estimate seasonal proportions of patient visits due to acute gastrointestinal illness (GI), assess factors influencing physicians' stool sample requests, their understanding of laboratory testing protocols and adherence to provincial stool request guidelines in three British Columbia (BC) health regions. METHODS: During a one-year period, eligible physicians were mailed four self-administered questionnaires used to estimate proportions of patients diagnosed with GI, related stool sample requests in the preceding month, and to assess factors prompting stool sample requests. RESULTS: The response rate overall for the initial comprehensive questionnaire was 18.6%; 7.4% responded to all four questionnaires. An estimated 2.5% of patient visits had a GI diagnosis; of these, 24.8% were asked to submit stool samples. Significant (p < 0.05) regional and seasonal variations were found in rates of GI and stool sample requests. Top-ranked factors prompting stool sample requests were: bloody diarrhoea, recent overseas travel, immunocompromised status, and duration of illness > 7 days; "non-patient" factors included: laboratory availability, time to receive laboratory results, and cost. Physicians' perceptions of which organisms were tested for in a 'routine' stool culture varied. INTERPRETATION: BC physicians appear to adhere to existing standardized guidelines for sample requests. This may result in systematic under-representation of certain diseases in reportable communicable disease statistics.

A GIS-driven integrated real-time surveillance pilot system for national West Nile virus dead bird surveillance in Canada.

BACKGROUND: An extensive West Nile virus surveillance program of dead birds, mosquitoes, horses, and human infection has been launched as a result of West Nile virus first being reported in Canada in 2001. Some desktop and web GIS have been applied to West Nile virus dead bird surveillance. There have been urgent needs for a comprehensive GIS services and real-time surveillance. RESULTS: A pilot system was developed to integrate real-time surveillance, real-time GIS, and Open GIS technology in order to enhance West Nile virus dead bird surveillance in Canada. Driven and linked by the newly developed real-time web GIS technology, this integrated real-time surveillance system includes conventional real-time web-based surveillance components, integrated real-time GIS components, and integrated Open GIS components. The pilot system identified the major GIS functions and capacities that may be important to public health surveillance. The six web GIS clients provide a wide range of GIS tools for public health surveillance. The pilot system has been serving Canadian national West Nile virus dead bird surveillance since 2005 and is adaptable to serve other disease surveillance. CONCLUSION: This pilot system has streamlined, enriched and enhanced national West Nile virus dead bird surveillance in Canada, improved productivity, and reduced operation cost. Its real-time GIS technology, static map technology, WMS integration, and its integration with non-GIS real-time surveillance system made this pilot system unique in surveillance and public health GIS.

Population distribution and burden of acute gastrointestinal illness in British Columbia, Canada.

BACKGROUND: In developed countries, gastrointestinal illness (GI) is typically mild and self-limiting, however, it has considerable economic impact due to high morbidity. METHODS: The magnitude and distribution of acute GI in British Columbia (BC), Canada was evaluated via a cross-sectional telephone survey of 4,612 randomly selected residents, conducted from June 2002 to June 2003. Respondents were asked if they had experienced vomiting or diarrhoea in the 28 days prior to the interview. RESULTS: A response rate of 44.3% was achieved. A monthly prevalence of 9.2% (95% CI 8.4-10.0), an incidence rate of 1.3 (95% CI 1.1-1.4) episodes of acute GI per person-year, and an average probability that an individual developed illness in the year of 71.6% (95% CI 68.0-74.8), weighted by population size were observed. The average duration of illness was 3.7 days, translating into 19.2 million days annually of acute GI in BC. CONCLUSION: The results corroborate those from previous Canadian and international studies, highlighting the substantial burden of acute GI.

Syndromic Surveillance of Norovirus using Over-the-counter Sales of Medications Related to Gastrointestinal Illness.

OBJECTIVE: To assess whether over-the-counter (OTC) sales of gastrointestinal illness (GI)-related medications are associated with temporal trends of reportable community viral, bacterial and parasitic infections. METHODS: The temporal patterns in weekly and seasonal sales of nonprescription products related to GI were compared with those of reportable viral, bacterial and parasitic infections in a Canadian province. RESULTS: Temporal patterns of OTC product sales and Norovirus activity were similar, both having highest activity in the winter months. In contrast, GI cases from both bacterial and parasitic agents were highest from late spring through to early fall. CONCLUSIONS: Nonprescription sales of antidiarrheal and antinauseant products are a good predictor of community Norovirus activity. Syndromic surveillance through monitoring of OTC product sales could be useful as an early indicator of the Norovirus season, allowing for appropriate interventions to reduce the number of infections.

Estimated Numbers of Community Cases of Illness Due to Salmonella, Campylobacter and Verotoxigenic Escherichia Coli: Pathogen-specific Community Rates.

OBJECTIVE: To estimate the annual number of cases of illness due to verotoxigenic Escherichia coli (VTEC), Salmonella and Campylobacter in the Canadian population, using data from the National Notifiable Disease registry (NND), estimates of under-reporting derived from several National Studies on Acute Gastrointestinal Illness, and the literature. METHODS: For each of the three pathogens (VTEC, Salmonella and Campylobacter), data were used to estimate the percentage of cases reported at each step in the surveillance system. The number of reported cases in the NND for each pathogen was then divided by these percentages. In cases where the pathogen-specific estimates were unavailable, data on acute gastrointestinal illness were used, accounting for differences between those with bloody and nonbloody diarrhea. RESULTS: For every case of VTEC, Salmonella and Campylobacter infection reported in the NND, there were an estimated 10 to 47, 13 to 37, and 23 to 49 cases annually in the Canadian population, respectively. CONCLUSIONS: The authors estimate that a significant number of infections due to VTEC, Salmonella and Campylobacter occur each year in Canada, highlighting the fact that these enteric pathogens still pose a significant health burden. Recognizing the significant amount of under-reporting is essential to designing appropriate interventions and assessing the impact of these pathogens in the population.

Estimating the burden of acute gastroenteritis, foodborne disease, and pathogens commonly transmitted by food: an international review.

The burden of foodborne disease is not well defined in many countries or regions or on a global level. The World Health Organization (WHO), in conjunction with other national public health agencies, is coordinating a number of international activities designed to assist countries in the strengthening of disease surveillance and to determine the burden of acute gastroenteritis. These data can then be used to estimate the following situations: (1) the burden associated with acute gastroenteritis of foodborne origin, (2) the burden caused by specific pathogens commonly transmitted by food, and (3) the burden caused by specific foods or food groups. Many of the scientists collaborating with the WHO on these activities have been involved in quantifying the burden of acute gastroenteritis on a national basis. This article reviews these key national studies and the international efforts that are providing the necessary information and technical resources to derive national, regional, and global burden of disease estimates.

Estimating the under-reporting rate for infectious gastrointestinal illness in Ontario.

BACKGROUND: In Ontario, infectious gastrointestinal illness (IGI) reporting can be represented by a linear model of several sequential steps required for a case to be captured in the provincial reportable disease surveillance system. Since reportable enteric data are known to represent only a small fraction of the total IGI in the community, the objective of this study was to estimate the under-reporting rate for IGI in Ontario. METHODS: A distribution of plausible values for the under-reporting rate was estimated by specifying input distributions for the proportions reported at each step in the reporting chain, and multiplying these distributions together using simulation methods. Input distributions (type of distribution and parameters) for the proportion of cases reported at each step of the reporting chain were determined using data from the Public Health Agency of Canada's National Studies on Acute Gastrointestinal Illness (NSAGI) initiative. RESULTS: For each case of enteric illness reported to the province of Ontario, the estimated number of cases of IGI in the community ranged from 105 to 1,389, with a median of 285, and a mean and standard deviation of 313 and 128, respectively. CONCLUSIONS: Each case of enteric illness reported to the province of Ontario represents an estimated several hundred cases of IGI in the community. Thus, reportable disease data should be used with caution when estimating the burden of such illness. Program planners and public health personnel may want to consider this fact when developing population-based interventions.

From stool to statistics: reporting of acute gastrointestinal illnesses in Canada.

BACKGROUND: Limitations associated with the under-reporting of enteric illnesses have long been recognized but the extent and variation of this under-reporting in Canada has not been examined. Given the public health value of surveillance data, a closer examination of under-reporting of enteric illnesses in Canada was warranted. METHODS: Paper-based surveys were administered (a) to all laboratories in Canada licensed to process stool specimens and (b) to all local public health authorities in two provinces. RESULTS: Of the laboratories surveyed, 67% (n=274) conducted on-site testing of stool specimens for enteric bacteria, 31% (n=126) for parasites and 10% (n=42) for viruses. In the year 2000, these laboratories processed 459,982 stool specimens, of which 5%, 15%, 8% and 19% were positive for enteric bacteria (excluding C. difficile), C. difficile, parasites and viruses, respectively. Variations in laboratory testing and health authority reporting protocols and policies were identified. Of the laboratory-confirmed cases of AGI reported to local public health authorities, 5% (n=846) were not reported to provincial counterparts. CONCLUSION: A significant proportion of AGI cases submitting stool specimens are not captured in Canada's passive surveillance system due to unknown etiology. A much smaller proportion of laboratory-confirmed cases reported to local public health authorities are not captured at the provincial or national level. Given that the number of laboratory-confirmed AGI cases represents such a small fraction of all community cases, strategies to compensate for under-reporting and efforts directed at harmonizing laboratory and local public health authority policies and practices would be welcomed.

The status of drinking water in Ontario, Canada (1992-1999).

OBJECTIVE: This study was conducted to investigate the characteristics of public water works (PWW) in southern Ontario with respect to their water sources and treatment regimes. METHODS: Data from 481 PWW covering the period 1992-1999 were collected and cartographic manipulations as well as descriptive analyses of the PWW attributes were performed. Tests of associations between different PWW attributes were done using Fisher's Exact test and Cochran-Mantel-Haenszel statistics. RESULTS: Water sources for the PWW included surface water (SW) (21% lakes; 13% rivers), ground water (GW) (64%) and mixed sources (2%). Most (81%) of the population was supplied with SW. Filtration was performed by 84% and 8% of the PWW using SW and GW, respectively. Similarly, disinfection was performed by 99% and 91% of the PWW using SW and GW respectively. There was no significant difference in treatment regimes between PWW in urban and those in rural areas but treatment regime was a function of water source. Overall, most PWW (87.8%) met the minimum treatment requirements of the then Ontario Drinking Water Objectives (ODWO). DISCUSSION: The study shows that most PWW complied with the minimum treatment requirements of the then ODWO. The minimum treatment required by the ODWO was disinfection for GW and both disinfection and filtration for SW. The non-compliant PWW will need to comply for continued provision of safe drinking water. Suffice it to say that both watershed protection and improved water treatment will be imperative for the continued provision of safe drinking water and control of waterborne diseases.

Syndromic surveillance of gastrointestinal illness using pharmacy over-the-counter sales. A retrospective study of waterborne outbreaks in Saskatchewan and Ontario.

OBJECTIVE: To ascertain if monitoring over-the-counter (OTC) drug sales could provide a timely syndromic surveillance method of detecting outbreaks of gastrointestinal illness. METHOD: This study evaluated the potential of a syndromic surveillance system by comparing retrospective pharmacy OTC sales of anti-nauseants and anti-diarrheals to emergency room visits and case numbers from two Canadian outbreaks related to water contamination by Cryptosporidium, and E.coli O157:H7 and Campylobacter. RESULTS: Local sales trends of weekly aggregate OTC products were comparable to the outbreak epidemic curves. Statistical control tests on the sales data indicated the start of the outbreak periods. CONCLUSIONS: An automated monitoring tool based on spatial and temporal trend analyses of daily OTC sales would provide supplemental community health information for public health officials that is timelier than currently available laboratory-based surveillance systems.

West Nile virus surveillance and diagnostics: A Canadian perspective.

A surveillance program has been in place since 2000 to detect the presence of West Nile virus (WNV) in Canada. Serological assays are most appropriate when monitoring for human disease and undertaking case investigations. Genomic amplification procedures are more commonly used for testing animal and mosquito specimens collected as part of ongoing surveillance efforts. The incursion of WNV into this country was documented for the first time in 2001 when WNV was demonstrated in 12 Ontario health units during the late summer and fall. In 2002 WNV activity was documented by avian surveillance in Ontario by mid-May with subsequent expansion of the virus throughout Ontario and into Quebec, Manitoba, Saskatchewan and Nova Scotia. Human cases were recorded in both Ontario and Quebec in 2002 with approximately 800 to 1000 probable, confirmed and suspect cases detected. The possible recurrence and further spread of WNV to other parts of Canada in 2003 must be anticipated with potential risk to public health. The continued surveillance and monitoring for WNV-associated human illness is necessary and appropriate disease prevention measures need to be in place in 2003.

Development of a geographic information-driven real-time surveillance system for disease surveillance.

To respond to emerging public health threats such as West Nile virus, an advanced geographic information systems (GIS) -driven Web-based real-time surveillance system was developed to serve the National West Nile virus dead bird surveillance programme in Canada. The development of this system uses real-time Web GIS technologies and services to enhance conventional real-time surveillance systems based on real-time GIS requirements. The system has three modules: QuickTrack, QuickMap and QuickManage. QuickTrack is the real-time surveillance module that supports data collection, edit and transfer. QuickMap is the real-time Web GIS module that provides comprehensive real-time GIS supports and services in public health surveillance and information sharing. The QuickManage module is a Web-based system management package used to manage the entire system. This system offers an effective approach to enhance real-time public health surveillance systems by integrating real-time Web GIS technologies and services. The system demonstrates that real-time Web GIS technologies can play an important role in enhancing public health surveillance systems.

Prospective surveillance of Canadian children with the haemolytic uraemic syndrome.

We determined prospectively the incidence of childhood diarrhoea associated haemolytic uraemic syndrome (D+ HUS) or HUS due to Streptococcus pneumoniae (SP+ HUS) in Canada through the Canadian Paediatric Surveillance Program (CPSP) network. From April 2000, to March 2002, 82% (1,886/2,300) of all Canadian paediatricians reported possible new cases of D+ HUS or SP+ HUS. Diagnosis was validated with a second questionnaire. There were a total of 136 children with D+ HUS (epidemic, n =15; endemic, n =121), corresponding to an annual incidence rate of 1.11 cases per 100,000 children under 16 years of age. Excluding incomplete forms, the annual incidence rate among endemic cases was 0.74 cases per 100,000. The provinces of Ontario (40%), Quebec (31%), and Alberta (18%) accounted for 89% of cases. Evidence of E. coli O157 or O157:H7 were found in 94% (79/84) of children who had positive stool cultures. The mortality rate was 4% (n =5) and 34% (n =41) of children underwent dialysis for a median of 12 days (2-60 days). SP-HUS was diagnosed in four children with pneumonia and pleural effusion (n =2) or meningitis (n =2) who survived. One child with positive direct Coombs testing had definitive evidence of SP+ HUS. The remaining three were considered possible cases. We conclude that SP+ HUS is rare in Canada. Over the last 15 years, the incidence of childhood D+ HUS in Canadian children may have decreased.