Rurality, Socioeconomic Status, and Residence in Environmental Risk Areas Associated with Increased Lyme Disease Incidence in Ontario, Canada: A Case-Control Study.

Background: Lyme disease (LD) is the most common tick-borne illness in North America. LD is acquired through exposure to the tick vector, Ixodes scapularis, known as the blacklegged tick. In Canada, LD is rapidly emerging, with the establishment of I. scapularis in many newly endemic regions posing a growing risk to local communities. In the Canadian context, many environmental and socioeconomic risk factors for human LD infection are yet to be ascertained and the degree of risk associated with residential and community exposure to ticks is not well known. Methods: We conducted a matched case-control study in southeastern Ontario, using LD patient data from provincial laboratory databases and uninfected population controls from 2014 to 2018. We aimed to identify area-level risk factors for LD and associations with residence in environmental risk areas, defined as areas with high model-predicted probability of I. scapularis occurrence, using the neighborhood dissemination area as the unit of analysis. Results: Using multivariable conditional logistic regression analysis, we identified that patients with LD had higher odds (odds ratio, OR; 95% confidence interval, CI) of living in neighborhoods with high probability of tick occurrence in the environment (OR = 2.2; 95% CI: 2.0-2.5), low walkability (OR = 1.6; 95% CI: 1.2-2.1), low material deprivation (OR = 1.4; 95% CI: 1.2-1.7), and low ethnic concentration (OR = 8.1; 95% CI: 6.7-9.9). We also found that the odds of LD infection for individuals residing in environmental risk areas was highest for those living in public health units (PHUs) with <250,000 population (OR = 3.0; 95% CI: 2.4-3.9) compared to those living in PHUs with >1,000,000 population (OR = 1.5; 95% CI: 1.1-2.1). Conclusion: This study shows that odds of human LD infection in Ontario, Canada is higher in less urbanized areas with higher socioeconomic status and indicates that exposure to ticks around the home residence or neighborhood is linked to increased odds of LD.

American dog ticks along their expanding range edge in Ontario, Canada.

The American dog tick, Dermacentor variabilis, is a tick of public and veterinary health importance in North America. Using passive tick surveillance data, we document distribution changes for the American dog tick in Ontario, Canada, from 2010 through 2018. Dermacentor variabilis submissions from the public were geocoded and aggregated-from large to small administrative geographies-by health region, public health unit (PHU) and Forward Sortation Area (FSA). PHU hot spots with high rates of D. variabilis submissions were (1) Brant County, Haldimand-Norfolk and Niagara Regional in the Central West region and (2) Lambton and Winsor-Essex County in the South West region. The number of established D. variabilis populations with ≥ 6 submissions per year increased significantly during the study at regional (PHUs: 22 to 31) and local (FSAs: 27 to 91) scales. The range of D. variabilis increased similarly to the positive control (Ixodes scapularis) during the study and in contrast to the static range of the negative control (Ixodes cookei). Submission hot spots were in warmer, low elevation areas with poorly drained soils, compared to the province's low submission areas. Dermacentor variabilis is spreading in Ontario and continued research into their vector ecology is required to assess medicoveterinary health risks.

A Computer Vision Approach to Identifying Ticks Related to Lyme Disease.

Background: Lyme disease (caused by Borrelia burgdorferi) is an infectious disease transmitted to humans by a bite from infected blacklegged ticks (Ixodes scapularis) in eastern North America. Lyme disease can be prevented if antibiotic prophylaxis is given to a patient within 72 hours of a blacklegged tick bite. Therefore, recognizing a blacklegged tick could facilitate the management of Lyme disease. Methods: In this work, we build an automated detection tool that can differentiate blacklegged ticks from other tick species using advanced computer vision approaches in real-time. Specially, we use convolution neural network models, trained end-to-end, to classify tick species. Also, advanced knowledge transfer techniques are adopted to improve the performance of convolution neural network models. Results: Our best convolution neural network model achieves 92% accuracy on unseen tick species. Conclusion: Our proposed vision-based approach simplifies tick identification and contributes to the emerging work on public health surveillance of ticks and tick-borne diseases. In addition, it can be integrated with the geography of exposure and potentially be leveraged to inform the risk of Lyme disease infection. This is the first report of using deep learning technologies to classify ticks, providing the basis for automation of tick surveillance, and advancing tick-borne disease ecology and risk management.

Monitoring the patterns of submission and presence of tick-borne pathogens in Ixodes scapularis collected from humans and companion animals in Ontario, Canada (2011-2017).

BACKGROUND: The universal nature of the human-companion animal relationship and their shared ticks and tick-borne pathogens offers an opportunity for improving public and veterinary health surveillance. With this in mind, we describe the spatiotemporal trends for blacklegged tick (Ixodes scapularis) submissions from humans and companion animals in Ontario, along with pathogen prevalence. METHODS: We tested tick samples submitted through passive surveillance (2011-2017) from humans and companion animals for Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum and Babesia microti. We describe pathogen prevalence in ticks from humans and from companion animals and constructed univariable Poisson and negative binomial regression models to explore the spatiotemporal relationship between the rates of tick submissions by host type. RESULTS: During the study, there were 17,230 blacklegged tick samples submitted from humans and 4375 from companion animals. Tick submission rates from companion animals were higher than expected in several public health units (PHUs) lacking established tick populations, potentially indicating newly emerging populations. Pathogen prevalence in ticks was higher in PHUs where established blacklegged tick populations exist. Borrelia burgdorferi prevalence was higher in ticks collected from humans (maximum likelihood estimate, MLE = 17.5%; 95% confidence interval, CI 16.97-18.09%) than from companion animals (9.9%, 95% CI 9.15-10.78%). There was no difference in pathogen prevalence in ticks by host type for the remaining pathogens, which were found in less than 1% of tested ticks. The most common co-infection B. burgdorferi + B. miyamotoi occurred in 0.11% of blacklegged ticks from humans and animals combined. Borrelia burgdorferi prevalence was higher in unengorged (21.9%, 95% CI 21.12-22.65%) than engorged ticks (10.0%, 95% CI 9.45-10.56%). There were no consistent and significant spatiotemporal relationships detected via regression models between the annual rates of submission of each host type. CONCLUSIONS: While B. burgdorferi has been present in blacklegged ticks in Ontario for several decades, other tick-borne pathogens are also present at low prevalence. Blacklegged tick and pathogen surveillance data can be used to monitor risk in human and companion animal populations, and efforts are under consideration to unite surveillance efforts for the different target populations.

Assessing human exposure to spotted fever and typhus group rickettsiae in Ontario, Canada (2013-2018): a retrospective, cross-sectional study.

BACKGROUND: Assessing the burden of rickettsial infections in Ontario, Canada, is challenging since rickettsial infections are not reportable to public health. In the absence of reportable disease data, we assessed the burden of rickettsial infections by examining patient serological data and clinical information. METHODS: Our retrospective, cross-sectional study included patients who had Rickettsia serological testing ordered by their physician, in Ontario, from 2013 to 2018. We tested sera from 2755 non-travel patients for antibodies against spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) using an indirect immunofluorescence assay (IFA) (positive IgG titers ≥1:64). We classified cases using a sensitive surveillance case definition: confirmed (4-fold increase in IgG titers between acute and convalescent sera with clinical evidence of infection), possible (single positive sera with clinical evidence) and previous rickettsial infection (single positive sera without clinical evidence). We classified cases seropositive for both SFGR and TGR as unspecified Rickettsia infections (URIs). RESULTS: Less than 5% of all patients had paired acute and convalescent sera tested, and of these, we found a single, laboratory-confirmed SFGR case, with a 4-fold increase in IgG titers and evidence of fever, maculopapular rash and headache. There were 45 possible (19 SFGR, 7 TGR, 19 URI) and 580 previous rickettsial infection (183 SFGR, 89 TGR, 308 URI) cases. The rate of positive tests for SFGR, TGR and URI combined (all case classifications) were 4.4 per 100,000 population. For confirmed and possible cases, the most common signs and symptoms were fever, headache, gastrointestinal complaints and maculopapular rash. The odds of having seropositive patients increased annually by 30% (odds ratio = 1.3, 95% confidence interval: 1.23-1.39). CONCLUSIONS: The rates of rickettsial infections in Ontario are difficult to determine. Based on confirmed and possible cases, rates are low, but inclusion of previous rickettsial infection cases would indicate higher rates. We highlight the need for education regarding the importance of testing acute and convalescent sera and consistent completion of the laboratory requisition in confirming rickettsial disease. We suggest further research in Ontario to investigate rickettsial agents in potential vectors and clinical studies employing PCR testing of clinical samples.

An apparent, locally acquired case of rickettsialpox (Rickettsia akari) in Ontario, Canada.

Rickettsialpox, caused by Rickettsia akari, is a spotted fever group rickettsiae transmitted to humans through the bite of the house mouse mite (Liponyssoides sanguineus). Worldwide, rickettsialpox is most commonly associated with exposure to rodents in urban environments. Here, we present the case of a 47-year-old woman from Brantford, Ontario, with fever, eschar on the right leg, expanding erythema, and right groin lymphadenopathy. Early in infection, R. akari serology was negative (IgG <1:64), but convalescent titre increased to 1:1,024. The patient did not travel outside of Ontario in the previous year. She denied any rodent or arthropod exposures in her home, but recently visited a friend's home infested with bats and mice. The patient was afebrile after treatment with doxycycline, with resolution of most clinical and laboratory findings in 5 days. This is the first rickettsialpox case reported in Canada and highlights the importance of obtaining convalescent serology to assist in the diagnosis of rickettsial infection.

La rickettsiose varicelliforme, causée par le Rickettsia akari, est une infection à rickettsie du groupe des fièvres pourprées qui est transmise aux humains par la piqûre d'acariens de la souris domestique (Liponyssoides sanguineus). Dans le monde, la rickettsiose varicelliforme est surtout associée à l'exposition à des rongeurs en milieu urbain. Les auteurs présentent le cas d'une femme de 47 ans de Brantford, en Ontario, qui faisait de la fièvre et avait des escarres sur la jambe droite, un érythème en expansion et une lymphadénopathie de l'aine droite. Au début de l'infection, la sérologie du R. akari était négative (IgG <1:64), mais pendant la convalescence, le titrage est passé à 1:1 024. La patiente n'avait pas fait de voyage hors de l'Ontario au cours de l'année précédente. Elle disait ne pas avoir été exposée à des rongeurs ou des arthropodes chez elle, mais avait récemment rendu visite à une amie dont la maison était infestée par des chauves-souris et des souris. La patiente était afébrile après le traitement à la doxycycline, et la plupart des observations cliniques et de laboratoire avaient disparu au bout de cinq jours. C'est le premier cas de rickettsiose varicelliforme signalé au Canada, ce qui fait ressortir l'importance d'obtenir la sérologie en phase de convalescence pour contribuer au diagnostic d'infection à rickettsie.

Recent Emergence of Anaplasma phagocytophilum in Ontario, Canada: Early Serological and Entomological Indicators.

Human granulocytic anaplasmosis (HGA), caused by the bacteria Anaplasma phagocytophilum, is transmitted to humans by blacklegged ticks (Ixodes scapularis) in eastern North America. To assess the emergence of A. phagocytophilum in Ontario, we analyzed patient serological and clinical data in combination with pathogen detection in blacklegged ticks from 2011 to 2017. Our sample population included all patients who had Anaplasma serological testing ordered by their physicians (n = 851). Eighty-three patients (10.8%) were A. phagocytophilum seropositive (IgG titers ≥ 1:64) and 686 (89.2%) were seronegative (IgG titers < 1:64). Applying published surveillance case definitions, we classified zero as confirmed, five as probable, and 78 as suspected cases. The percentage of seropositive patients remained generally stable at 13.6%. Seropositive patients were most often adult females, 40-59 years of age, and reported nonspecific signs and symptoms, such as fatigue, headache, and fever. Higher seropositivity rates (≥ 1.5 patients per 100,000 population) occurred in eastern and northwestern Ontario. The percentage of A. phagocytophilum-positive blacklegged ticks, through passive and active surveillance, was 0.4 and 1.1%, respectively, and increased over time. Serological and entomological indicators of A. phagocytophilum activity increased in areas of the province with established blacklegged tick populations. The risk of HGA is presently low in Ontario; however, further research is required to document the epidemiology of HGA in the province. To minimize the impact of HGA emergence in Ontario, increased awareness and education of the public and health-care providers is recommended, with consideration to making HGA a reportable infection in Ontario.

Occurrence and distribution of Ambylomma americanum as determined by passive surveillance in Ontario, Canada (1999-2016).

The lone star tick, Amblyomma americanum, is spreading northward from its historical stronghold in the southeastern United States. As a vector and biting pest, public and veterinary health officials must remain vigilant of the lone star tick's expanding range. We use ticks submitted to Public Health Ontario Laboratory (1999-2016) to describe the spatial and temporal dynamics of A. americanum in Ontario, Canada, as well as submitter demographics. We identified 847 A. americanum submissions during the surveillance period, with 773 (91.3%) non-travel-related and 74 (8.7%) travel-related submissions. Annual A. americanum submissions increased over the surveillance period. Approximately 91% of non-travel-related submissions were adult ticks and 9% were nymphs. The highest submission rates were from individuals living in the Eastern and South West regions of the province. Adult specimens were primarily submitted from May through July and nymphs from March through September. Higher numbers of submissions were from young children (<10 years) and older adults (55-74 years), with equal proportions of male and female submitters. The majority of travel-related submissions were from travellers returning from the southeastern United States (i.e., Florida, North Carolina, South Carolina, Tennessee, Texas). Amblyomma americanum distribution is scattered in Ontario and submissions are likely the consequence of ongoing detection of adventive specimens. Further tick dragging is required to confirm the presence of established lone star tick populations in the province. Given the relatively rapid expansion of blacklegged ticks, Ixodes scapularis, populations in Ontario, we expect climate change to facilitate the range of expansion of A. americanum into the province. We propose an algorithm for identifying A. americanum-risk areas, which will aid public and veterinary health officials when assessing the risks posed by lone star ticks.

A field-based indicator for determining the likelihood of Ixodes scapularis establishment at sites in Ontario, Canada.

The emergence of the vector Ixodes scapularis in Ontario, Canada poses a significant public health risk. Both passive and active surveillance approaches have been employed by public health professionals (i.e., government employees) to monitor for the range expansion of this tick. Field surveillance using drag sampling for questing ticks is a recognized and effective method to identify reproducing tick populations. The degree of effort (i.e., number of visits per site) can enhance the sensitivity and specificity of surveillance, but increased effort conflicts with the cost to public health for field surveillance. Here we developed an indicator to determine the likelihood of I. scapularis establishment based on field sampling results. Field data from two established populations of I. scapularis in Ontario were incorporated with previous analyses of surveillance data to create the indicator, which is in the form of a scoring system. The life stage(s) collected, overall abundance and past surveillance findings from a site are all considered and a level is assigned for the likelihood of I. scapularis establishment based on current field sampling results. The likelihood levels are non-zero (i.e., no I. scapularis detected, but risk still present due to adventitious ticks), low, medium or high, and recommendations for future surveillance and public health measures are provided. The indicator was validated against field sampling results from five other established sites in the province and correctly categorized all five areas as high likelihood of establishment. The indicator was also applied to field sampling results from 36 sites of unknown status that were visited twice during the period of 2014-2016. There was substantial agreement of levels between measurements, as calculated using a weighted kappa. The indicator can assist public health professionals with the interpretation of field sampling results and direct their efforts for ongoing surveillance and public health interventions for I. scapularis-borne diseases, including Lyme disease.

Human pathogens associated with the blacklegged tick Ixodes scapularis: a systematic review.

BACKGROUND: The blacklegged tick Ixodes scapularis transmits Borrelia burgdorferi (sensu stricto) in eastern North America; however, the agent of Lyme disease is not the sole pathogen harbored by the blacklegged tick. The blacklegged tick is expanding its range into areas of southern Canada such as Ontario, an area where exposure to blacklegged tick bites and tick-borne pathogens is increasing. We performed a systematic review to evaluate the public health risks posed by expanding blacklegged tick populations and their associated pathogens. METHODS: We followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for conducting our systematic review. We searched Ovid MEDLINE, Embase, BIOSIS, Scopus and Environment Complete databases for studies published from 2000 through 2015, using subject headings and keywords that included "Ixodes scapularis", "Rickettsia", "Borrelia", "Anaplasma", "Babesia" and "pathogen." Two reviewers screened titles and abstracts against eligibility criteria (i.e. studies that included field-collected blacklegged ticks and studies that did not focus solely on B. burgdorferi) and performed quality assessments on eligible studies. RESULTS: Seventy-eight studies were included in the final review, 72 were from the US and eight were from Canada (two studies included blacklegged ticks from both countries). Sixty-four (82%) studies met ≥ 75% of the quality assessment criteria. Blacklegged ticks harbored 91 distinct taxa, 16 of these are tick-transmitted human pathogens, including species of Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, Rickettsia, Theileria and Flavivirus. Organism richness was highest in the Northeast (Connecticut, New York) and Upper Midwest US (Wisconsin); however, organism richness was dependent on sampling effort. The primary tick-borne pathogens of public health concern in Ontario, due to the geographic proximity or historical detection in Ontario, are Anaplasma phagocytophilum, Babesia microti, B. burgdorferi, Borrelia miyamotoi, deer tick virus and Ehrlichia muris-like sp. Aside from B. burgdorferi and to a much lesser concern A. phagocytophilum, these pathogens are not immediate concerns to public health in Ontario; rather they represent future threats as the distribution of vectors and pathogens continue to proliferate. CONCLUSIONS: Our review is the first systematic assessment of the literature on the human pathogens associated with the blacklegged tick. As Lyme disease awareness continues to increase, it is an opportune time to document the full spectrum of human pathogens transmittable by blacklegged ticks.

A modified Centers for Disease Control and Prevention gravid trap for easier mosquito collection.

The original Centers for Disease Control and Prevention (CDC) gravid trap, with its mesh collection bag, can cause considerable damage to the captured mosquitoes. In an effort to reduce this damage and keep costs at a minimum, we modified our existing CDC gravid traps to accept a collection cup from a CDC light trap. This modification allowed for easier transport, freezing, storage, and removal of the mosquitoes. Modifying the CDC gravid traps takes little expertise or resources and can be completed quickly.

Attraction of Culex pipiens/restuans (Diptera: Culicidae) mosquitoes to bird uropygial gland odors at two elevations in the Niagara region of Ontario.

In an effort to determine whether female Culex pipiens L. and Culex restuans Theobald mosquitoes (Diptera: Culicidae) are attracted to crow, Corvus brachyrhynchus, uropygial gland secretions, CDC miniature light traps (baited with CO2 but with the lights removed) were placed at approximately 1.5- and 5-m elevations, in 10 trees in awoodlot near Niagara Falls, Canada. These traps were assigned either a bird odor or a blank control. Bird odors were created by attaching cotton swabs coated with crow uropygial gland secretions to the trap intake. A significantly greater number of Cx. pipiens/ restuans were found in the 5-m traps compared with 1.5-m traps, with a significant number attracted to the bird odor over the no odor traps at the 5-m elevation, but not at 1.5 m. We also found more Aedes vexans (Meigen) in the 1.5-m traps than the 5-m traps; however, presence or absence of bird odor did not influence the distribution of Ae. vexans.

Analysis of nectar and honeydew feeding in Aedes and Ochlerotatus mosquitoes.

Most research has investigated floral nectar as a source of carbohydrates for mosquitoes and has ignored homopteran honeydew. We have assessed the prevalence of honeydew and nectar feeding in 7 species of mosquitoes collected from Algonquin Provincial Park, Ontario, Canada. In total, 403 individuals were analyzed by thin-layer chromatography, with melezitose and stachyose as honeydew-indicator sugars. From the 403 individuals, 214 contained sugars, of which only 8.8% had the honeydew-indicating sugars. We conclude that female Aedes and Ochlerotatus mosquitoes in Algonquin Provincial Park seem to feed infrequently on honeydew.