Evaluation of the SNAP® 4Dx® plus test for the detection of Dirofilaria immitis antigen and characterization of exposure to tick-borne pathogens in wild canids in southern Ontario

Population-level surveys for Dirofilaria immitis in wild canids typically rely on identification of the parasite at necropsy. More recently, some studies have employed the use of the SNAP® 4Dx® Plus test. However, since the assay was designed for use with domestic dogs it needs to be validated for use with wild canids for accurate interpretation of results. We therefore evaluated the performance of the SNAP® 4Dx® Plus test for detection of D. immitis in wild canids in southern Ontario. Overall, 199 wild canid carcasses were collected from across the region and assessed for the presence of D. immitis parasites at necropsy; ten were infected. Lung tissue extract (LE) and thoracic fluid filter paper extract (TFE) prepared from each wild canid were tested via the SNAP® 4Dx® Plus test, which simultaneously tests for the presence of D. immitis antigen and antibodies to Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp. The prevalence adjusted bias adjusted kappa (PABAK) and Gwet's first-order-agreement coefficient (AC1) were used to assess the level of agreement between sample pairs. The PABAK and AC1 between LF and TFE applied to the SNAP® 4Dx® Plus test and the necropsy-confirmed D. immitis status indicated a very high level of agreement for all sample pairs. Compared to necropsy-confirmed D. immitis status, the estimated sensitivity and specificity of the SNAP® 4Dx® Plus test for D. immitis antigen in LE was 80 % (95 % CI 44.4-97.5%) and 98.9 % (95 % CI 96.2-99.9%), respectively. For the TFE, the sensitivity was 70 % (95 % CI 34.8-93.3%) and the specificity was 97.9 % (95 % CI 94.7-99.4%). With respect to the tick-borne pathogen components, 1.5 % (3/199; 95 % CI 0.3-4.5%) of wild canids tested positive for B. burgdorferi antibody; 1.0 % (2/199; 95 % CI 0-3.8%) of LE samples were positive and 0.5 % (1/199; 95 % CI 0-3.1%) of TFE samples were positive. No samples tested positive for antibody to Anaplasma spp. (95 % CI 0-2.3%) or Ehrlichia spp. (95 % CI 0-2.3%). Collectively, the results suggest that the SNAP® 4Dx® Plus test may be a suitable test for use with LE and TFE for the detection of D. immitis antigen in wild canids from southern Ontario.

Factors associated with Echinococcus multilocularis infection in coyotes in southern Ontario

Echinococcus multilocularis was recently reported in wild canids across southern Ontario, a newly recognized endemic area in Canada. In such areas, a comprehensive understanding of factors associated with infection in definitive hosts (wild canids) is critical for mitigating risk of transmission to humans. However, little is known about the transmission dynamics of the parasite in definitive hosts for this region. A study was therefore carried out to investigate the association of host-level (sex, body condition), environmental (southern Ontario region, land cover), temporal (season, hunting season, calendar year) and extraneous factors (submitter type) with E. multilocularis infection in coyotes in southern Ontario. Between November 2015 and March 2017, 416 coyotes were collected from across the region as part of a study that investigated the prevalence and distribution of the parasite in wild canids; approximately 24% of coyotes were positive for E. multilocularis. Associations between infection and factors of interest were assessed via a mixed-effects logistic regression model with a random intercept for submitter to account for clustering. Coyotes with poor body condition were at greater odds of E. multilocularis infection than those in good condition (odds ratio [OR] 2.14; 95% CI: 1.08-4.26; p = .030). A negative association was observed between infection in coyotes and the proportion of natural land in a coyote's estimated home range (OR: 0.67; 95% CI: 0.52-0.85; p = .001). Coyotes from the western region of southern Ontario had lower odds of infection compared to coyotes from the central region (OR: 0.26; 95% CI: 0.12-0.55; p < .001). These results can be used to help guide future public health prevention strategies for human alveolar echinococcosis.

Prevalence and distribution of Dirofilaria immitis infection in wild canids in southern Ontario

Wild canids represent a potential reservoir host for Dirofilaria immitis infection in dogs in Ontario. Since wild canids are not protected by chemoprophylaxis, understanding the epidemiology of D. immmitis in these populations may help elucidate the background risk of infection for dogs. The aim of this study was to determine the prevalence and distribution of D. immitis infection in wild canids across southern Ontario. From February 2016 to March 2017, 290 wild canid carcasses (273 coyotes and 17 foxes) were collected from across the region and assessed for the presence of D. immitis at the time of necropsy. Overall, D. immitis infection was identified in 4.8% (95% CI 2.8-8.0%) of these wild canid carcasses. Among coyotes, 5.1% (95% CI 3.0-8.5%) were positive; no evidence of D. immitis was found in the 17 foxes. Dirofilaria immitis infections in wild canids were detected in two regions of southern Ontario: 12 of the 14 D. immitis infections were detected in the south-western region and two were detected in the eastern region. Our findings provide preliminary insights into the prevalence and geographical distribution of D. immitis in coyotes and foxes in southern Ontario.

Echinococcus multilocularis Infection, Southern Ontario, Canada

Alveolar echinococcosis, the disease caused by infection with the intermediate stage of the Echinococcus multilocularis tapeworm, is typically fatal in humans and dogs when left untreated. Since 2012, alveolar echinococcosis has been diagnosed in 5 dogs, 3 lemurs, and 1 chipmunk in southern Ontario, Canada, a region previously considered free of these tapeworms. Because of human and animal health concerns, we estimated prevalence of infection in wild canids across southern Ontario. During 2015–2017, we collected fecal samples from 460 wild canids (416 coyotes, 44 foxes) during postmortem examination and analyzed them by using a semiautomated magnetic capture probe DNA extraction and real-time PCR method for E. multilocularis DNA. Surprisingly, 23% (95% CI 20%–27%) of samples tested positive. By using a spatial scan test, we identified an infection cluster (relative risk 2.26; p = 0.002) in the western-central region of the province. The cluster encompasses areas of dense human population, suggesting zoonotic transmission.

Public Health Follow-up of Suspected Exposure to Echinococcus multilocularis in Southwestern Ontario

In the 3 years since the first report of canine alveolar echinococcosis (AE) in Ontario, three additional cases have been diagnosed in the province. Of the four cases reported to date, three have had no known history of travel outside the province. It is possible that this development is an indication of previously unrecognized environmental contamination with Echinococcus multilocularis eggs in some areas of the province. If so, there is the potential for an emerging threat to human health. This article describes a local public health department's investigation of the possible exposure to E. multilocularis of a number of individuals who had had contact with the latest of the four cases of canine AE, and summarizes a comprehensive decision process that can be used by public health departments to assist in the follow-up of such exposures.

Development of a tiered framework for public health capacity in Canada

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Select SARS reports were qualitatively analyzed for usage of “capacity”/“capacities”.

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Public health capacity can be sub-divided into 17 individual capacity components.

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These components can be organized into five tiers to build a capacity framework.

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This framework can be used to guide capacity assessment and building efforts.

Tuberculosis outbreak in a long-term care facility

OBJECTIVES

Tuberculosis (TB) was a major cause of morbidity and mortality in Canada early in the 20th century. Elderly populations in Canada remain at high risk for TB disease. Elderly patients may present atypically, with the result that many active cases can remain undiagnosed. We present an outbreak of TB that occurred in a Residential and Long-Term Care (LTC) facility in Ontario.

METHODS

Case finding was carried out through the conventional concentric circle approach. Three rounds of tuberculin skin testing were conducted at 8-12 week intervals. Laboratory analysis was conducted at the Public Health Ontario Laboratories. An indoor air quality assessment was conducted to determine whether inadequate engineering controls were a transmission risk factor.

RESULTS

A case of active pulmonary TB was confirmed in May 2010 in a staff member at the facility. By January 2011, 3 additional active cases and 24 latent tuberculosis infections among residents and staff had been identified. Genotyping methods confirmed that the 4 active cases were infected by an identical strain. Nine of 15 locations tested in the facility had air exchange rates below published guidelines.

CONCLUSION

Prompt reporting of the initial case allowed for a quick initiation of the epidemiologic investigation. Given the epidemiology of TB in elderly populations, outbreaks should remain a concern for LTC facilities and physicians, even in jurisdictions of low TB incidence. Baseline and annual TB screening for residents and staff, early diagnosis of active TB, and adequate ventilation are important to reduce the incidence of disease.

Cost analysis of public health influenza vaccine clinics in Ontario

OBJECTIVE

Public health in Ontario delivers, promotes and provides each fall the universal influenza immunization program. This paper addresses the question of whether Ontario public health agencies are able to provide the influenza immunization program within the Ministry of Health fiscal funding envelope of $5 per dose.

METHODS

Actual program delivery data from the 2006 influenza season of Wellington-Dufferin-Guelph Public Health (WDGPH) were used to create a model template for influenza clinics capturing all variable costs. Promotional and administrative costs were separated from clinic costs. Maximum staff workloads were estimated. Vaccine clinics were delivered by public health staff in accordance with standard vaccine administration practices.

RESULTS

The most significant economic variables for influenza clinics are labour costs and number of vaccines given per nurse per hour. The cost of facility rental was the only other significant cost driver. The ability of influenza clinics to break even depended on the ability to manage these cost drivers. At WDGPH, weekday flu clinics required the number of vaccines per nurse per hour to exceed 15, and for weekend flu clinics this number was greater than 21. We estimate that 20 vaccines per hour is at the limit of a safe workload over several hours. Managing cost then depends on minimizing hourly labour costs.

DISCUSSION

The results of this analysis suggest that by managing the labour costs along with planning the volume of patients and avoiding expensive facilities, flu clinics can just break even. However, any increased costs, including negotiated wage increases or the move to safety needles, with a fixed revenue of $5.00 per dose will negate this conclusion.

Measurement of hepatic sterol synthesis in the Mongolian gerbil in vivo using [3H]water: diurnal variation and effect of type of dietary fat

The hepatic synthesis of sterol was measured in the male Mongolian gerbil (Meriones unguiculatus) in vivo following the administration of [3H]water by monitoring the incorporation of radioactivity into digitonin-precipitable sterol. A diurnal rhythm in cholesterol synthesis was exhibited under conditions of ad libitum feeding with alternating 12-hour periods of light (0200 to 1400 hr) and dark (1400 to 0200 hr). The zenith was reached between 1500 and 2100 hr and the nadir approximately 10-12 hours later between 0200 and 0400 hr, which provided a zenith/nadir ratio of 9.6 to 1.0. The in vivo rates of hepatic sterol synthesis and plasma cholesterol levels were measured in gerbils fed semi-purified diets containing either 19.5% beef tallow + 0.5% safflower, 20% lard, or 20% safflower oil and widely differing ratios of polyunsaturated: saturated fatty acids. All diets were equalized to contain 0.01% cholesterol and 0.05% plant sterol. After 3 days on the experimental diets, the mean rates of cholesterol synthesis (nmol/g liver per hr) were 41.5, 26.6, and 13.8 for animals fed the diets containing beef tallow, lard, and safflower oil, respectively. After 7 and 14 days, synthetic rates were lowest in the gerbils fed safflower oil as were also the plasma cholesterol levels. These results indicate that the type of dietary lipid can significantly influence the in vivo rate of sterol biosynthesis in gerbil liver. This response may contribute, at least in part, to the observed differences in plasma cholesterol levels.