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Background West Nile virus (WNV) is a mosquito-borne flavivirus, first detected in the Western Hemisphere in 1999 and spread across North America over the next decade. Though endemic in the most populous areas of North America, few studies have estimated the healthcare costs associated with WNV. The objective of this study was to determine direct healthcare costs attributable to WNV illness in Ontario, Canada. Methods We conducted a cost-of-illness study on incident laboratory confirmed and probable WNV infected subjects identified from the provincial laboratory database from Jan 1, 2002 through Dec 31, 2012. Infected subjects were linked to health administrative data and matched to uninfected subjects. We used phase-of-care methods to calculate costs for 3 phases of illness: acute infection, continuing care, and final care prior to death. Mean 10-day attributable costs were reported in 2014 Canadian dollars, per capita. Sensitivity analysis was conducted to test the impact of WNV neurologic syndromes on healthcare costs. Results One thousand five hundred fifty-one laboratory confirmed and probable WNV infected subjects were ascertained; 1540 (99.3%) were matched to uninfected subjects. Mean age of WNV infected subjects was 49.1 ± 18.4 years, 50.5% were female. Mean costs attributable to WNV were $1177 (95% CI: $1001, $1352) for acute infection, $180 (95% CI: $122, $238) for continuing care, $11,614 (95% CI: $5916, $17,313) for final care - acute death, and $3199 (95% CI: $1770, $4627) for final care - late death. Expected 1-year costs were $13,648, adjusted for survival. Three hundred seventeen infected subjects were diagnosed with at least one neurologic syndrome and greatest healthcare costs in acute infection were associated with encephalitis ($4710, 95% CI: $3770, $5650). Conclusions WNV is associated with increased healthcare resource utilization across all phases of care. High-quality studies are needed to understand the health system impact of vector-borne diseases and evaluate the cost effectiveness of novel WNV interventions.

With the emerging Zika virus (ZIKV) epidemic, serologic diagnosis relies on a labor-intensive IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and confirmation by a plaque reduction neutralization test (PRNT). To streamline serologic testing, several commercial assays have been developed. Our aim was to compare the commercial Euroimmun anti-ZIKV IgM and IgG assays to the reference MAC-ELISA and PRNT currently in use. Serum specimens submitted to Public Health Ontario Laboratory, Canada, were tested for IgM and IgG using the Euroimmun assays and the results were compared with those from MAC-ELISA. The PRNT was performed on positive or equivocal specimens using either MAC-ELISA or Euroimmun assays, MAC-ELISA-inconclusive specimens, and a convenience sample of specimens negative by both assays (cohort 1). Another set of specimens selected on the basis of PRNT results was subsequently tested by the Euroimmun assays (cohort 2). MAC-ELISA was positive, equivocal, negative, and inconclusive in 57/223, 15/223, 147/223, and 4/223 specimens, respectively. Among the 76 specimens that were MAC-ELISA positive, equivocal, or inconclusive, 30 (39.5%) were Euroimmun IgM and/or IgG positive or equivocal. Among the 147 MAC-ELISA-negative specimens, 136 (92.5%) were Euroimmun IgM and IgG negative. The sensitivity of the combined Euroimmun IgM/IgG against the PRNT was 83% (cohort 1) and 92% (cohort 2), whereas the specificity was 81% (cohort 1) and 65% (cohort 2). The combined Euroimmun IgM/IgG showed good specificity (92.5%) but suboptimal sensitivity (39.5%) compared with that of the MAC-ELISA. However, the sensitivity of the combined Euroimmun IgM/IgG against the PRNT was significantly higher (83 to 92%). More studies are needed before commercial assays are implemented for routine ZIKV serologic diagnosis.

With the emerging Zika virus (ZIKV) epidemic, accessible real-time reverse transcription-PCR (rRT-PCR) assays are needed to streamline testing. The commercial Altona Diagnostics RealStar ZIKV rRT-PCR test kit (Altona PCR) has been approved for emergency use authorization by the U.S. FDA. Our aim was to verify the Altona PCR by comparing it to the CDC-designed dual-target ZIKV rRT-PCR reference assay (reference PCR) and describe the demographics of patients tested for ZIKV by rRT-PCR in Ontario, Canada. A large set of clinical specimens was tested for ZIKV by the Altona PCR and the reference PCR. Positive or equivocal specimens underwent PCR and Sanger sequencing targeting the ZIKV NS5 gene. A total of 671 serum specimens were tested by the reference PCR: 58 (8.6%) were positive, 193 (28.8%) were equivocal, and 420 (62.6%) were negative. Ninety percent of the reference PCR-positive patients were tested in the first 5 days after symptom onset. The Altona PCR was performed on 284/671 specimens tested by the reference PCR. The Altona PCR was positive for 53/58 (91%) reference PCR-positive specimens and 16/193 (8%) reference PCR-equivocal specimens; the ZIKV NS5 PCR was positive for all 68 Altona PCR-positive specimens and negative for all 181 Altona PCR-negative specimens that underwent the NS5 PCR. The Altona PCR has very good sensitivity (91%) and specificity (97%) compared to the reference PCR. The Altona PCR can be used for ZIKV diagnostic testing and has less extensive verification requirements than a laboratory-developed test.

In spite of a greatly reduced incidence rate due to vaccination, mumps outbreaks continue to occur in several areas of the world, sometimes in vaccinated populations. This article describes an outbreak in a highly vaccinated population in southwestern Ontario, Canada, and the challenges encountered in interpreting the results of diagnostic tests used in the outbreak. During the outbreak, patients were interviewed and classified according to the outbreak case definition, and specimens were collected for diagnostic testing according to Ontario guidelines. Twenty-seven individuals were classified as confirmed cases ( n = 19) or suspect cases ( n = 8) according to the case definition, only 9 of which were laboratory-confirmed cases: 7 confirmed by reverse transcriptase PCR (RT-PCR) and 2 by IgM serology. All 19 confirmed cases represented patients who were associated with secondary schools in the local area and had been vaccinated against mumps with one ( n = 2) or two ( n = 17) doses of the measles-mumps-rubella (MMR) vaccine. This is the first published report of an outbreak of mumps in Ontario in which all confirmed cases had been vaccinated against the disease. It highlights the limitations of and difficulties in interpreting current mumps diagnostic tests when used in vaccinated individuals.

We examined which respiratory pathogens were identified during screening for Middle East respiratory syndrome coronavirus in 177 symptomatic travelers returning to Ontario, Canada, from regions affected by the virus. Influenza A and B viruses (23.1%) and rhinovirus (19.8%) were the most common pathogens identified among these travelers.

In August 2014, children's hospitals in Kansas City, Missouri and Chicago, Illinois notified the Centers for Disease Control and Prevention (CDC) about increased numbers of pediatric patients hospitalized with severe respiratory illness (SRI). In response to CDC reports, Public Health Ontario Laboratories (PHOL) launched an investigation of patients being tested for enterovirus D-68 (EV-D68) in Ontario, Canada. The purpose of this investigation was to enhance our understanding of EV-D68 epidemiology and clinical features. Data for this study included specimens submitted for EV-D68 testing at PHOL from September 1, 2014 to October 31, 2014. Comparisons were made between patients who tested positive for the virus (cases) and those testing negative (controls). EV-D68 was identified in 153/907 (16.8%) of patients tested. In the logistic regression model adjusting for age, sex, setting and time to specimen collection, individuals younger than 20 years of age were more likely to be diagnosed with EV-D68 compared to those 20 and over, with peak positivity at ages 5-9 years. Cases were not more likely to be hospitalized than controls. Cases were more likely to be identified in September than October (OR 8.07; 95% CI 5.15 to 12.64). Routine viral culture and multiplex PCR were inadequate methods to identify EV-D68 due to poor sensitivity and inability to differentiate EV-D68 from other enterovirus serotypes or rhinovirus. Testing for EV-D68 in Ontario from July to December, 2014 detected the presence of EV-D68 virus among young children during September-October, 2014, with most cases detected in September. There was no difference in hospitalization status between cases and controls. In order to better understand the epidemiology of this virus, surveillance for EV-D68 should include testing of symptomatic individuals from all treatment settings and patient age groups, with collection and analysis of comprehensive clinical and epidemiological data.

Background This investigation was done to assess vaccine effectiveness of one and two doses of the measles, mumps and rubella (MMR) vaccine during an outbreak of mumps in Ontario. The level of coverage required to reach herd immunity and interrupt community transmission of mumps was also estimated. Methods Information on confirmed cases of mumps was retrieved from Ontario’s integrated Public Health Information System. Cases that occurred between Sept. 1, 2009, and June 10, 2010, were included. Selected health units supplied coverage data from the Ontario Immunization Record Information System. Vaccine effectiveness by dose was calculated using the screening method. The basic reproductive number ( R 0 ) represents the average number of new infections per case in a fully susceptile population, and R 0 values of between 4 and 10 were considered for varying levels of vaccine effectiveness. Results A total of 134 confirmed cases of mumps were identified. Information on receipt of MMR vaccine was available for 114 (85.1%) cases, of whom 63 (55.3%) reported having received only one dose of vaccine; 32 (28.1%) reported having received two doses. Vaccine effectiveness of one dose of the MMR vaccine ranged from 49.2% to 81.6%, whereas vaccine effectiveness of two doses ranged from 66.3% to 88.0%. If we assume vaccine effectiveness of 85% for two doses of the vaccine, vaccine coverage of 88.2% and 98.0% would be needed to interrupt community transmission of mumps if the corresponding reproductive values were four and six. Interpretation Our estimates of vaccine effectiveness of one and two doses of mumps-containing vaccine were consistent with the estimates that have been reported in other outbreaks. Outbreaks occurring in Ontario and elsewhere serve as a warning against complacency over vaccination programs.

We identified ticks submitted by the public from 2008 through 2012 in Ontario, Canada, and tested blacklegged ticks Ixodes scapularis for Borrelia burgdorferi and Anaplasma phagocytophilum. Among the 18 species of ticks identified, I. scapularis, Dermacentor variabilis, Ixodes cookei and Amblyomma americanum represented 98.1% of the 14,369 ticks submitted. Rates of blacklegged tick submission per 100,000 population were highest in Ontario's Eastern region; D. variabilis in Central West and Eastern regions; I. cookei in Eastern and South West regions; and A. americanum had a scattered distribution. Rates of blacklegged tick submission per 100,000 population were highest from children (0–9 years old) and older adults (55–74 years old). In two health units in the Eastern region (i.e., Leeds, Grenville & Lanark District and Kingston-Frontenac and Lennox & Addington), the rate of submission for engorged and B. burgdorferi-positive blacklegged ticks was 47× higher than the rest of Ontario. Rate of spread for blacklegged ticks was relatively faster and across a larger geographic area along the northern shore of Lake Ontario/St. Lawrence River, compared with slower spread from isolated populations along the northern shore of Lake Erie. The infection prevalence of B. burgdorferi in blacklegged ticks increased in Ontario over the study period from 8.4% in 2008 to 19.1% in 2012. The prevalence of B. burgdorferi-positive blacklegged ticks increased yearly during the surveillance period and, while increases were not uniform across all regions, increases were greatest in the Central West region, followed by Eastern and South West regions. The overall infection prevalence of A. phagocytophilum in blacklegged ticks was 0.3%. This study provides essential information on ticks of medical importance in Ontario, and identifies demographic and geographic areas for focused public education on the prevention of tick bites and tick-borne diseases.