The utility of measles and rubella IgM serology in an elimination setting, Ontario, Canada, 2009-2014.

In Canada, measles was eliminated in 1998 and rubella in 2000. Effective measles and rubella surveillance is vital in elimination settings, hinging on reliable laboratory methods. However, low-prevalence settings affect the predictive value of laboratory tests. We conducted an analysis to determine the performance of measles and rubella IgM testing in a jurisdiction where both infections are eliminated. 21,299 test results were extracted from the Public Health Ontario Laboratories database and 1,239 reports were extracted from the Ontario Integrated Public Health Information System (iPHIS) from 2008 and 2010 for measles and rubella, respectively, to 2014. Deterministic linkage resulted in 658 linked measles records (2009-2014) and 189 linked rubella records (2010-2014). Sixty-six iPHIS measles entries were classified as confirmed cases, of which 53 linked to laboratory data. Five iPHIS rubella entries were classified as confirmed, all linked to IgM results. The positive predictive value was 17.4% for measles and 3.6% for rubella. Sensitivity was 79.2% for measles and 100.0% for rubella. Specificity was 65.7% for measles and 25.8% for rubella. Our study confirms that a positive IgM alone does not confirm a measles case in elimination settings. This has important implications for countries that are working towards measles and rubella elimination.

A Canadian framework for applying the precautionary principle to public health issues.

The precautionary principle has influenced environmental and public health policy. It essentially states that complete evidence of a potential risk is not required before action is taken to mitigate the effects of the potential risk. The application of precaution to public health issues is not straightforward and could paradoxically cause harm to the public's health when applied inappropriately. To avoid this, we propose a framework for applying the precautionary principle to potential public health risks. The framework consists of ten guiding questions to help establish whether a proposed application of the precautionary principle on a public health matter is based on adequacy of the evidence of causation, severity of harm and acceptability of the precautionary measures.

Helicobacter pylori and the prevention of gastric cancer.

BACKGROUND: Helicobacter pylori is an important cause of stomach cancer that infects a substantial proportion of the Canadian adult population. H pylori can be detected by noninvasive tests and effectively eradicated by medical treatment. Screening for and treatment of H pylori may represent a significant opportunity for preventive oncology. METHODS: Cancer Care Ontario organized a workshop held in Toronto, Ontario, on October 24 and 25, 2002, to: review the current state of knowledge regarding H pylori treatment and cancer prevention; determine if there is currently sufficient evidence to consider the promotion of H pylori treatment for the purpose of cancer prevention; identify critical areas for research; and advise Cancer Care Ontario on H pylori and cancer prevention. RESULTS: Workshop participants developed a number of recommendations for research into the relationship between H pylori and stomach cancer, including determining the prevalence of infection in different regions of Canada, the pathogenetic sequence of carcinogenesis from H pylori infection, and the implementation of a prospective observational study. INTERPRETATION: Although the rate of H pylori infection is declining in Canada and the treatment of H pylori is generally accepted to be safe, the evidence to date may not warrant the implementation of population screening for H pylori infection to prevent gastric carcinoma in average-risk populations. Rather, a demonstration project is needed to estimate prevalence, evaluate the merits of screening, measure patient compliance and physician participation, develop education materials, establish a registry for monitoring and evaluation, and develop a quality assurance framework.

Identification and containment of an outbreak of SARS in a community hospital.

BACKGROUND: Severe acute respiratory syndrome (SARS) is continuing to spread around the world. All hospitals must be prepared to care for patients with SARS. Thus, it is important to understand the transmission of this disease in hospitals and to evaluate methods for its containment in health care institutions. We describe how we cared for the first 2 patients with SARS admitted to our 419-bed community hospital in Richmond Hill, Ont., and the response to a SARS outbreak within our institution. METHODS: We collected clinical and epidemiological data about patients and health care workers at our institution who during a 13-day period had a potential unprotected exposure to 2 patients whose signs and symptoms were subsequently identified as meeting the case definition for probable SARS. The index case at our hospital was a patient who was transferred to our intensive care unit (ICU) from a referral hospital on Mar. 16, 2003, where he had been in close proximity to the son of the individual with the first reported case of SARS in Toronto. After 13 days in the ICU, a diagnosis of probable SARS was reached for our index case. Immediately upon diagnosis of our index case, respiratory isolation and barrier precautions were instituted throughout our hospital and maintained for a period of 10 days, which is the estimated maximum incubation period reported for this disease. Aggressive surveillance measures among hospital staff, patients and visitors were also maintained during this time. RESULTS: During the surveillance period, 15 individuals (10 hospital staff, 3 patients and 2 visitors) were identified as meeting the case definition for probable or suspected SARS, in addition to our index case. All but 1 individual had had direct contact with a symptomatic patient with SARS during the period of unprotected exposure. No additional cases were identified after infection control precautions had been implemented for 8 days. No cases of secondary transmission were identified in the 21 days following the implementation of these precautions at our institution. INTERPRETATION: SARS can easily be spread by direct personal contact in the hospital setting. We found that the implementation of aggressive infection control measures is effective in preventing further transmission of this disease.