Table of Contents. Table of Contents Executive Summary Introduction West Nile Virus Eastern Equine Encephalitis...

Transcription

1 Table of Contents Table of Contents... 1 Executive Summary... 2 Introduction... 5 West Nile Virus... 5 Eastern Equine Encephalitis Lyme Disease Program Evaluation Conclusion Appendices

2 Executive Summary Vector-borne diseases are diseases that are transmitted to humans or other animals by an insect or other arthropod. In Ontario, West Nile Virus (WNV) and Lyme disease are the two main endemic vector-borne diseases of public health importance as both of these diseases can be acquired within the province. Another vector-borne disease of concern in Ontario is Eastern Equine Encephalitis (EEE). EEE is a rare but serious viral disease spread by mosquitoes that can affect people and horses. The EEE virus has been detected in Ontario in horses and mosquitoes but, to date, no human cases have been reported. PPH s (PPH) 2014 Vector-Borne Disease Prevention Plan identified activities Peel Public Health would carry out in order to comply with Ontario Regulation 199/03 Control of West Nile Virus. Under Ontario Regulation 199/03, the local Medical Officer of Health (MOH) is required to conduct a risk assessment of the conditions pertaining to WNV in the health unit. The risk assessment identifies the probability of human infection based on WNV surveillance activities as well as other pertinent information elements. Completion of the risk assessment in accordance with the regulation offers guidance to the MOH regarding appropriate WNV reduction activities, and if needed, provides a review of appropriate mosquito reduction activities (i.e. larviciding or adulticiding) and their effectiveness. PPH s approach to WNV control emphasized disease prevention in humans and protection of the environment through region-wide surveillance and Integrated Mosquito Management (IMM). This meant an emphasis on public education, source reduction and larviciding. If the level of WNV in Peel increased, then education, surveillance and reduction activities would be intensified. Surveillance activities indicate that WNV is endemic in Peel and that WNV levels can fluctuate widely from year to year. In 2014, there was a significant decrease in the number of positive mosquito batches in Peel Region as there were 22 positive mosquito batches compared to 51 positive mosquito batches in There was also a decrease in the number of human cases as no confirmed or probable human cases were reported compared to five confirmed or probable human cases in Source reduction and larviciding focused on Culex pipiens and Culex restuans mosquitoes, the main vectors of WNV in Peel. These two mosquito species breed in water that has been stagnant for more than a week in sites such as catch basins, roadside ditches, culverts and artificial containers (abandoned swimming pools, tires, buckets, etc.). These mosquito habitats were priority targets for elimination through improved maintenance and for larviciding where stagnant water could not be removed. Other mosquito habitats such as marshes and natural ponds were only treated if they were found to be important to local WNV transmission. Surveillance of mosquitoes provided an early warning of the risk to human health. This information was used to enhance mosquito reduction and education efforts in high risk areas to interrupt the amplification of WNV before it had a significant impact on human health. 2

3 The West Nile Virus component of the 2014 Vector-Borne Disease Prevention Plan was consistent with the recommendation from the United States Centers for Disease Control and Prevention. Eastern Equine Encephalitis (EEE) is a mosquito-borne viral disease which occurs primarily in the eastern half of the United States where it causes disease in humans and horses. The main EEE transmission cycle is between birds and mosquitoes. The most important mosquito species in maintaining the bird-mosquito transmission cycle is Culiseta melanura. Mosquito surveillance conducted by PPH over the last several years has found low numbers of this species in the Region of Peel. In 2014, PPH continued to monitor the prevalence and distribution of Cs. melanura using the region-wide adult mosquito CDC light trap network. In 2014, one Cs. melanura was found in a CDC light trap located in north Mississauga. From 2011 to 2013, PPH followed the 2011 MOHLTC Eastern Equine Encephalitis Surveillance and Management Guidelines which recommended the inclusion of bridge vectors in the EEE testing program. During this time period EEE bridge vector mosquitoes found in the Caledon traps were subjected to EEE testing. Based on the low number of positive mosquitoes in the province, the MOHLTC suggested that the testing of EEE bridge vectors no longer needed to be undertaken. In 2014, Peel Health did not conduct EEE testing on bridge vectors. If the virus had been found in the local mosquito population or if a confirmed case of EEE involving a human or horse occurred in Peel, then increased surveillance and public education would have commenced. Lyme disease is included in Ontario Regulations 558/91 and 559/91 making it both a reportable and communicable disease under the Health Protection and Promotion Act. Lyme disease is an illness caused by the bacterium, Borrelia burgdorferi, which can be spread through the bite of an infected tick. In Ontario, the disease is spread by the black-legged tick (Ixodes scapularis) which is sometimes called the deer tick. To date, an established black-legged tick population has not been identified in the Region of Peel, although there are numerous sites in Peel region that have a combination of environmental factors that would support new populations of black-legged ticks to become established in the future. In 2014, three confirmed Lyme disease cases were reported in Peel, two were associated with European travel and one was acquired in southern Ontario. In August, active tick surveillance was undertaken at the Caledon Equestrian Park near Palgrave in preparation for the 2015 Pan Am games. The tick dragging sessions did not identify 3

4 any ticks. In 2014, PPH continued passive tick surveillance by examining ticks brought into PPH offices by the public. Eleven tick samples were submitted to PPH: 3 Ixodes scapularis - black-legged tick (Areas found: Mississauga, Baltimore Maryland, Brampton or Campbellford) 7 Dermacentor variabilis - dog tick 1 Amblyomma cajennense - Cayenne tick (Area found: Honduras) Specimens associated with human contact were submitted to the Central Public Health Laboratory (CPHL) in Toronto for species confirmation. The three black-legged ticks were sent to the Public Health Agency of Canada s (PHAC) National Microbiology Laboratory in Winnipeg for Lyme disease testing. One tick was found to be positive for Borrelia burgdorferi. The positive tick was submitted to Peel Health by a Peel resident whose exposure was in either in Brampton or Campbellford Ontario. 4

5 Introduction The Region of Peel has had a West Nile Virus Prevention Plan since In 2009, Peel Public Health developed a Vector-Borne Disease Prevention Plan which focused primarily on WNV but also addressed other vector-borne diseases of concern. The 2014 Vector-Borne Disease Prevention Plan followed the blueprint of the plan from the previous year as it included components for Lyme disease, EEE as well as WNV. This 14 th annual report provides information about the transmission and health effects of the vector-borne diseases of concern in Peel, as well as the details and results of surveillance and risk reduction activities in West Nile Virus WNV was first detected in Peel in birds and mosquitoes in Locally acquired human illness occurred for the first time in 2002 when 112 residents had laboratory evidence of WNV infection (55 suspect cases, 20 probable cases and 37 confirmed cases, including two deaths). However, the case definition has changed since If current human case definitions were used, there would have been 18 confirmed cases in One of the goals of the Vector-Borne Disease Prevention Plan is to minimize the impact of WNV with a regional surveillance program involving humans and mosquitoes (adults and larvae). The surveillance program guides the Integrated Mosquito Management (IMM) activities which include mosquito larvae reduction, stagnant water site remediation, and risk communication activities. Surveillance activities continue to indicate that WNV is endemic in Peel and that WNV levels can fluctuate widely from year to year. In 2014, PPH continued human and mosquito surveillance, public education and larval mosquito reduction activities. WNV Human Surveillance Program The human case surveillance program is intended to detect human cases of WNV in Peel. All probable and confirmed human cases identified by hospitals and physicians are reported to the local public health department. The MOHLTC has developed case definitions and diagnostic test criteria (refer to Appendix A). In 2014, there were no probable or confirmed human cases of WNV in Peel Region. The last year no human cases were recorded in Peel Region was Table 1 presents the number of human cases of WNV in Peel Region from 2002 to In 2002, 57 probable and confirmed cases of WNV were reported based on the case definitions at the time. If the present day case definition was applied, there would have been 18 confirmed human cases in

6 Table 1: Numbers of Human Cases by Municipality (confirmed and probable), Region of Peel, Year Region of Peel Mississauga Brampton Caledon In 2002, there were a total of 112 cases with laboratory and/or clinical evidence of WNV infection; 57 cases were classified as probable or confirmed. In subsequent years, only confirmed cases were reported as a result of changes in disease classifications. If the present day classifications were applied, there would have been 18 confirmed human cases in Comparison with Other Ontario Health Units As of December 31, 2014, there were 10 confirmed or probable WNV human cases in Ontario, compared to 55 in 2013, 262 in 2012 and 71 in Toronto had the most confirmed cases in Ontario in 2014 with three, followed by Halton Region (2), the City of Ottawa (2), Chatham-Kent (1), Lambton County (1 travel related case), and Simcoe- Muskoka District (1 case from a First Nations community). Comparison with Other Provinces In 2014, there were a total of 21 human cases in Canada compared to 109 cases in 2013, 453 cases in 2012, and 108 cases in In 2014, positive human cases were found in Ontario (10), Quebec (6) and Manitoba (5). No fatalities were reported. Of the 21 human cases, 10 were classified as West Nile virus non-neurological syndrome, 9 as West Nile virus neurological syndrome and two as unclassified/unspecified. 6

7 The decrease in WNV activity in Ontario can be attributed in part to the fact that the summer of 2014 was cooler than that of 2013 and Higher temperatures speed up the mosquito life cycle as well as increasing the replication rate of the virus in infected mosquitoes. The colder than normal winter also may have contributed to lower WNV activity in 2014 as the mortality of the over-wintering adult Culex mosquitoes can be impacted by extreme cold winter temperatures. WNV Adult Mosquito Surveillance Program 2014 PPH monitored WNV activity in the local mosquito population from June 17 to October 1 in GDG Environnement Ltee provided PPH with mosquito identification and WNV and EEE testing services as part of the monitoring program. Map 1 shows the locations for the fixed traps set in Peel Region in Thirty-one fixed CDC light traps were distributed by Regional ward, with a minimum of one trap per ward across Peel: 17 in the City of Mississauga, nine in the City of Brampton and five in the Town of Caledon. The red dots denote traps from which positive WNV mosquitoes were collected. In 2014, there were 13 traps that collected positive mosquitoes (six in Mississauga and seven in Brampton). Adult specimens collected in the 31 mosquito traps were sent to GDG Environnement Lteé. As requested by Peel Public Health, a maximum of two pools for WNV (Culex complex only) were tested per trap by during the first six weeks of the adult surveillance program. Up to four pools of WNV vector mosquitoes were tested in the remaining 11 weeks in the traps located in Brampton and Mississauga. The rationale behind increasing WNV tests in the later part of the season is based on historical test results which indicate that the WNV bridging vectors generally do not test positive until late July or early August. Pool sizes contained a maximum of 50 mosquitoes. These pools were homogenized, extracted and viral tested. The gold standard real time RT-PCR test was used according to the MOHLTC criteria. In 2014, there were 40,022 mosquitoes collected, with 29,541 of those being identified and 17,548 of those being WNV vectors (Table 2). The most abundant vector species in Peel in 2014 were Aedes vexans vexans and Culex pipiens/restuans (Table 2). The majority of positive pools were Culex pipiens/restuans with 15 (68%) (Table 3). Other positive pools included six pools of Aedes vexans vexans (27%) and one pool of Ochlerotatus japonicus (5%) (Table 3). Of the 22 WNV positive mosquito batches that were identified in 2014, 16 were in Brampton and six were in Mississauga. 7

8 Map 1: Map of Mosquito Trap Location, Region of Peel,

9 Table 2: West Nile Virus Vector Species Abundance Totals 2014 Species Quantity Percentage approximate (%) Ae vexans vexans 9, Cx. pipiens / restuans 4, Oc japonicus 1, Oc trivittatus 1,275 7 An punctipennis Oc triseriatus/hendersoni An quadrimaculatus Cx species 15 <1 Cx salinarius 8 <1 Total 17, Source: GDG Environnement Lteé: based on PCR data Table 3: West Nile Virus Vector Species Testing Pools 2014 Species Pools Specimens Positive Pools Cx pipiens/restuans 386 4, Ae vexans vexans 332 6,344 6 Cx salinarius Oc japonicus Cx species Oc triseriatus/hendersoni An punctipennis Oc trivittatus Total 1,110 12, Source: GDG Environnement Lteé: based on PCR data 9

10 Figure 1 compares the annual number of positive mosquito batches per week for the 2002 baseline year and Based on previous years data, positive mosquito batches are likely to occur any time after June. There are occasions when no positive mosquitoes are found at sites during the weeks tested. The year-to-year onset and peak of WNV-positive mosquito batches vary. This is due to a range of factors including weather (temperature and rainfall), the effectiveness of the multi-faceted prevention program in reducing breeding sites on public and private property, and larviciding catch basins and surface water on public property. The first positive trapping event in 2014 occurred during the week of July 20 in south Mississauga (first positive collected July 22) and the last positive batch in 2014 occurred during the week of September 14 (last positive collected September 17) in Brampton. The weekly onset and cessation of positive mosquito batches were relatively typical of a normal year as positive mosquitoes were reported in week 30 and during the last trapping event of the season in week 38 (Figure 1). Figure 1: WNV Positive Mosquito Batches by Week of Collection, Region of Peel, 2002, # of Positive Mosquito Pools by Week (N=128) (N=22) (N=51) (N=65) Note: Larviciding was not undertaken in

11 Table 4 presents the MIR s for the Culex species grouped by municipality in Peel Region in Higher MIR s are usually indicative of greater WNV activity among a given species but can be unreliable when the sample size is less than 1,000. Since fewer than 1,000 Culex mosquitoes were collected in Caledon, this data may not fully represent the MIR rate in this municipality if positive mosquito batches were reported in Table 4: Minimum Infection Rates* of Culex Species in Each Municipality in the Region of Peel, Municipality Vector Species Actual Number Positive MIR* Tested Batches Culex pipiens/restuans Mississauga 1, Culex salinarius Brampton Caledon Peel Region Culex pipiens/restuans Culex salinarius Culex pipiens/restuans Culex salinarius Culex pipiens/restuans Culex salinarius 2, Not reportable sample size under 1,000 4, *The Minimum Infection Rate (MIR) is calculated as the number of positive batches of infected mosquitoes of a given species divided by the total number of mosquitoes of a given vector species that were tested for the presence of the virus, expressed by 1,000. WNV Larval Mosquito Surveillance Program 2014 Larval surveillance is useful in guiding WNV prevention and reduction activities. It is used to determine the location, species and population densities of mosquitoes. Larval surveillance activities are vital for predicting adult emergence and establishing optimal times for implementation of larval reduction measures. In 2014, staff surveyed a variety of aquatic habitats for the presence of mosquito larvae from early June to late September. Potential breeding sites were identified by referring back to breeding site information collected in previous years and by stagnant water complaints received through the Environmental Health Customer Contact Centre or on-line reporting form. 11

12 Increased larval monitoring and aquatic site mapping was undertaken on public lands in the vicinity of Caledon Equestrian Park near Palgrave in preparation for the 2015 Pan Am games. This enhanced surveillance assisted in identifying sites of concern that may require larvicide applications prior to or during the 2015 Pan Am equestrian events. Larval surveillance was conducted at 2,086 potential mosquito breeding sites identified by WNV staff on publicly-owned lands across the Region in Table 5 provides a breakdown of the distribution of surface water sites monitored by municipality in 2014 relative to previous years. In 2014, over half (52%) of the potential breeding sites monitored were in Mississauga, 17% in Brampton, and 30% were in Caledon. The higher number of surface water sites identified and monitored by Peel Public Health in Mississauga can be attributed to having more field staff dedicated to larval surveillance in this municipality as historically Mississauga had higher levels of WNV activity than Brampton and Caledon. The reduction of surface water sites monitored in 2014 compared to 2013 can be attributed to less precipitation being recorded in the spring and summer months of There were mm of precipitation reported by Environment Canada from April 1 to September 30 at Toronto International Airport in 2014 compared to mm in Table 5: Number of Surface Water Sites Monitored by Municipality, Region of Peel 2002, Year Peel Region Mississauga Brampton Caledon ,274 1, , , ,015 1, ,086 1, Note: Monitoring season ran from May-September 2002 to 2008, and June-September since 2009 Figure 2 presents the larval surveillance results by breeding site type (habitat) in Peel Region in Culverts (32.6%) and ditches (29.8%) comprised over two thirds of sites with larvae present. These are the most difficult locations to contain mosquito populations using control measures because of their relative mosquito abundance and site effectiveness at holding standing water. 12

13 Figure 2: Type of Sites Found to Contain Mosquito Larvae, Region of Peel, 2014 Woodland Pool 3.8% Storm Water Management Wet Pond 3.9% Other 3.6% Marsh 1.8% Natural Pond 1.3% Artificial Container 1.2% Field Pool 9.7% Culvert 32.6% Creek 12.2% Ditch 29.8% Species Identification - Larval Analysis In 2014, staff identified 7,002 mosquito larvae from June to September, an increase from 2013 when 5,622 larvae were identified. There were 14 different species of larvae identified in 2014 compared to 10 in The majority (71%) were of the Culex species - Cx. pipiens/restuans and Cx. salinarius which are key WNV vectors as well as Cx. territans, a non-wnv vector. This figure is slightly higher than the percentage of larvae identified as Culex species in 2013 (68 %). Aedes vexans vexans, a confirmed WNV bridge vector in Ontario, accounted for 19% of larvae identified in Oc. japonicus, an invasive species that is a WNV vector, accounted for approximately one percent of larvae identified. 13

14 Larval Mosquito Reduction A major part of the Region of Peel Vector-Borne Disease Program is to conduct activities to reduce the number of vector mosquitoes. This goal can be achieved by preventing the emergence of mosquitoes by eliminating or altering habitats (source reduction) to make them less conducive to mosquito breeding, and by pesticide treatment at the larval stage to impede their development into viable adult mosquitoes. Source reduction is important and the Region of Peel s public education and outreach program highlights the need for eliminating stagnant water. However, it is very difficult and cost-prohibitive to eliminate all breeding sites because very little water is required for most female mosquitoes to lay their eggs, particularly in the case of the Culex species. Therefore, the prevention plan relies heavily on the larviciding program. The purpose of the larviciding program is to reduce mosquito abundance, especially the Culex species. It is easier, more efficient and cost effective to control mosquito populations by treating at the larval stage with larvicides before adult mosquitoes emerge and become more widely dispersed. Habitats of importance include roadside catch basins, ditches, culverts, discarded tires, unused swimming pools, field pools and containers left outdoors. These breeding sites promote the emergence of multiple mosquito species because of standing or slow-moving water and the presence of decaying organic matter which serves as food for the larvae. Special attention and efforts were directed towards monitoring catch basins and surface water breeding sites such as ditches, culverts and field pools. Catch basin networks are extensive in urban and suburban environments. They retain a small amount of water and organic matter in the form of sediment that collects in the sump of the catch basin. The majority of catch basins in Peel Region have been found to contain larvae. Surface water breeding sites are many in number and type and can change from year to year requiring a systematic approach to their surveillance and treatment. Habitat modification, which includes altering the habitat to eliminate standing water, can also reduce the potential to breed mosquitoes. In 2014, Peel Public Health staff continued to work with municipal departments to pursue all effective measures to achieve this outcome. Catch Basin Treatment Three rounds of roadside municipal catch basin larviciding were conducted in The municipal catch basins were treated with Altosid Pellets with the exception of the catch basins located within Environmentally Sensitive Areas (ESAs) which were treated with VectoLex 2 WSP (Bacillus sphaericus). Non-roadside catch basins were 14

15 treated once with a single application of Altosid Briquets which provide over 90 days of control. A prophylactic approach was followed where catch basins were treated regardless of whether water was present. Factors such as catch basin cleaning, new subdivisions, parked vehicles and construction prevented access to some roadside catch basins and resulted in a variance in treatments during each round. Table 6 summarizes the catch basin treatment activities across Peel Region in A total of 300,700 roadside catch basins in Peel Region were treated with kg of Altosid Pellets (round 1, 101,442; round 2, 100,005; round 3, 99,253), and 157 roadside catch basins in Peel Region were treated with Vectolex water soluble pellets (WSP). Altosid XR Briquets were applied to 1,482 non-roadside catch basins including those located in or along parks, private backyards, daycares, government buildings, social housing complexes and long-term care facilities in Peel in Table 6: Summary of Catch Basin Treatments, Region of Peel, 2014 Number of catch basins Treated Round 1 Round 2 Round 3 Quantity of Altosid (kg) Number of Pouches Number of catch basins Treated Quantity of Altosid (kg) Number of Pouches Number of catch basins Treated Quantity of Altosid (kg) Number of Pouches Altosid Briquett es Number of catch basins Treated Brampton 49, , , Caledon 3, , , Mississauga 48, , , ,038 Peel 101, , , ,482 Source: GDG Environnement Lteé, 2014 Surface Water Treatment Monitoring mosquito larval habitats to assess the presence and abundance of mosquito larvae was conducted using a standard plastic dipper following the Ministry of Environment and Climate Change s (MOECC) sequential sampling method. On each surveillance visit, the standing water site was given a pool rating based on the total number of larvae observed. Larval samples were also collected and identified by PPH staff. In Peel Region, if vectors were identified, the surface water site was referred to GDG Environnement Lteé for treatment from June 1 to September 30. In 2014, 648 surface water treatments were undertaken (Table 7) compared to 586 treatments in GDG Environnement Lteé staff reported an additional 497 surface water visits did not result in treatment as the sites were dry, had low larvae counts or vector species were not present at the time of their site visits. 15

16 Table 7: Number of Surface Water Sites Treated, Region of Peel, 2014 Month Number of Sites Treated Qty of Vectobac Applied (L) Treated Area (ha) June July August September Total Source: GDG Environnement Lteé, 2014 Environmentally Sensitive Areas Permission from the Ontario Ministry of Natural Resources (MNR) and a special wetlands permit were obtained to allow for larviciding within specific Environmentally Sensitive Areas (ESAs) in Peel. Six ESAs were noted in the permit: Rattray Marsh, Cawthra Woods, Heartlake Wetland Complex, Credit River Wetland (O Neil Court Storm Water Management Pond), Credit River Marsh and Lorne Park Prairie. ESAs are defined by the MOECC and spatial location data is obtained from the MNR. There are two circumstances when a Sensitive Area and Species Protocol are required by the MOE in order to obtain a permit and apply a larvicide. The first situation requiring the protocol occurs when a catch basin is either located within an ESA or it is known to be the last catch basin before an outfall into an ESA. In Peel Region, there were 132 municipal catch basins that met one of these criteria. VectoLex WSP was used to control mosquito larvae in ESA catch basins. The second situation requiring the Sensitive Areas and Species Protocol occurs when a standing water site falls within an ESA. In Peel Region, there are several standing water sites that meet this criterion including multiple sites within Rattray Marsh, Cawthra Woods, Heartlake Wetland Complex, Credit River Wetland (O Neil Court Storm Water Management Pond), Credit River Marsh and Lorne Park Prairie. Pesticide Effects Surveillance In 2014, pesticide effects surveillance was included in the WNV component of the Vector-Borne Disease Plan. As in previous years, PPH continued to work with other municipalities, conservation authorities and the MOECC to ensure our larviciding program did not negatively impact the ecosystem. PPH also used larvicide products that have been identified as having the least environmental impact. Staff from the Vector-Borne Disease team conducted field inspections to verify the service provider contracted to conduct larviciding in Peel was applying the larvicides in accordance with MOECC regulations. 16

17 Efficacy and Quality Assurance PPH conducted quality assurance monitoring of roadside catch basins during all three rounds of treatment. VBD students were assigned map zones and noted the catch basins that did not have a coloured paint dot associated with the latest application round. GDG Environnement Lteé was provided a list of the missed catch basins which were to be revisited within 24 hours of notification. PPH has conducted catch basin methoprene efficacy tests since larviciding was initiated in the Region of Peel in The Vector-Borne Disease team follows the post-larviciding monitoring for methoprene efficacy protocol noted in the MOE Permit Applicant Guide for Municipalities and Health Units: Controlling Mosquito Larvae for Prevention and/or Control of West Nile Virus. PPH staff collected mosquito pupae and roadside catch basin water following each application round of the pellets from a small number of catch basins. The pupae were kept in jars covered with mesh lids and observed daily to see if viable adults successfully emerged over a period of 4 days. The number of dead pupae, dead adults and live adults were counted. In 2014,174 pupae were collected and 47 viable adults emerged, resulting in 73% efficacy which is the same efficacy result as recorded in 2013 and very close to the 74% efficacy calculated in Public Education and Community Outreach Activities PPH has developed various educational resources about personal protective measures and individual and household activities that prevent or discourage the breeding of mosquitoes. The resources include flyers, fact sheets, posters, mailers and newspaper advertisements. These resource materials are made available on the Region of Peel Vector-Borne Disease website The website is also used to post WNV surveillance results, update larviciding activities and provide the public with access to the VBD Prevention Plan as well as annual technical reports dating back to In 2014, as in previous years, West Nile Virus advertisements were placed in the local weekly newspapers. In May, the advertisement focused on reducing and reporting stagnant water sites. The monthly advertisements from June until August focused on West Nile Virus personal protection measures. As a result of low WNV activity, newspaper advertisements were deemed not to be necessary in September. As in 2013, residents or organizations were encouraged to sign up at to receive notification of positive WNV activity in Peel. In addition, the electronic WNV notification database for institutions and for parks and recreation facilities that were located within a one kilometre range of each of the 31 fixed mosquito trap sites continued to be utilized. An was sent to institutions and to parks and recreation facilities when a positive mosquito batch was reported in their area. 17

18 There was also one Health Professionals Update on WNV that was distributed to physicians in the region of Peel in The Health Professionals Update can be found at: wnv.pdf Eastern Equine Encephalitis Eastern Equine Encephalitis, commonly referred to as EEE, is a viral disease of wild birds that is transmitted to horses and humans by mosquitoes. Of the North American mosquito-borne diseases, EEE appears to be the most severe human pathogen; approximately 33% of people who develop EEE die of the disease and many survivors have long-term health effects. In Ontario, outbreaks of EEE have occurred sporadically among horses but no human cases have ever been confirmed. The lack of verified human cases of EEE in Ontario is not entirely understood since human cases have repeatedly been reported in several states bordering the province. In 2014, there was no EEE positive mosquito pools reported in Ontario; however, there were 24 equine cases reported in the province. Adult mosquito surveillance conducted over the last several years has found the key z species for EEE, Culiseta melanura, to be present in Peel but in very low numbers. In 2014, PPH continued to monitor the prevalence and distribution of Cs. melanura using the region-wide adult mosquito CDC light trap network. One Cs. melanura was collected in a CDC light trap in north Mississauga in late July. This mosquito tested negative for EEE. While Cs. melanura surveillance is the primary aim when developing management plans for EEE, other vector species play important roles in transmission dynamics and maintenance of the virus in nature. Aedes vexans vexans, Ochlerotatus anadensis and Coquillettidia perturbans are key bridge vectors of EEE virus in Ontario. From 2011 to 2013, Peel Public Health followed the MOHLTC Eastern Equine Encephalitis Surveillance and Management Guidelines which recommended the inclusion of the three bridge vectors in the EEE testing program. Based on the low number of positive mosquitoes in the province, the MOHLTC recommended not testing bridge vectors for EEE in The Cs. melanura resting box monitoring program that was initiated in north Brampton in 2010 was not undertaken in 2014 as the low numbers of Cs. melanura collected over the years, did not justify the continuation of this pilot project. In 2014, Peel Health relied upon adult and larval mosquito surveillance data in decision-making about EEE public education and mosquito reduction activities. 18

19 Lyme Disease The endemic areas in Ontario include Long Point Provincial Park, Turkey Point Provincial Park, Rondeau Provincial Park, Point Peleé National Park, Prince Edward Point National Wildlife Area, Wainfleet Bog Conservation Area, and St. Lawrence Islands National Park. It should be noted that ticks can be spread by birds, in particular, songbirds that feed off the ground. Because these birds are migratory, there is the potential for new populations of ticks to spread across the province. Therefore, one does not necessarily have to be in an endemic or high-risk area to be at risk of encountering ticks and the disease. In 2014, three confirmed Lyme disease cases were reported in Peel. Two were associated with European travel and one was acquired in southern Ontario. In August, active tick surveillance was undertaken at the Caledon Equestrian Park near Palgrave in preparation for the 2015 Pan Am games. The tick dragging sessions did not identify any ticks. In 2014, Peel Public Health continued passive tick surveillance by examining ticks brought into Peel Public Health offices by the public. Eleven tick samples were submitted to Peel Public Health: 3 Ixodes scapularis - black-legged 7 Dermacentor variabilis - dog tick 1 Amblyomma cajennense - Cayenne tick Specimens associated with human contact were submitted to the Central Public Health Laboratory (CPHL) in Toronto for species confirmation. The three black-legged ticks were sent to the Public Health Agency of Canada s (PHAC) National Microbiology Laboratory in Winnipeg for Lyme disease testing. One tick was found to be positive for Borrelia burgdorferi. The positive tick was submitted to Peel Health by a Peel resident who came in contact with the tick in Brampton or Campbellford, Ontario Table 8 summarizes the number of Peel residents who have contracted Lyme disease since

20 Table 8: Lyme Disease Cases in the Region of Peel, Confirmed Year Cases There are concerns that changes of climatic conditions such as warmer seasons could lead to conditions that are favourable for the establishment of black-legged tick populations in many parts of the province. The expansion of the black-legged tick population would likely result in an increase in human cases in the province. 20

21 Program Evaluation Peel s VBD team manager and supervisor meet at the end of each season to identify needs and program improvements. Some program key needs/improvements that were identified for 2015 include: All human case follows ups (WNV and Lyme disease) to be conducted year round by the three VBD team leaders under the supervision of the VBD supervisor. Evaluate and cease monitoring any storm water management pond that has a history of no larval mosquitoes for three consecutive years (with the exception of complaints from the public). New ponds or ponds that are productive will continue to be monitored and treated when necessary. Due to the 2015 Pan Am Games, surveillance in the vicinity of the Palgrave Equestrian Centre will be enhanced for the period leading up to and during the Games. Conclusion Surveillance activities continue to indicate that WNV is endemic in Peel and it is reasonable to assume that the virus will return to Peel at some level in Peel Public Health will continue to conduct surveillance, public education and larval mosquito reduction activities as these are essential WNV program components in a jurisdiction where WNV has been detected in a previous season. PPH will also continue public and physician education on Lyme disease symptoms, testing and prevention activities in In addition, if an established tick population is identified or if there is evidence of a confirmed case of Lyme disease that has been acquired locally, then active surveillance including tick dragging will be undertaken. In 2015, PPH will also continue to monitor the prevalence and distribution of EEE vector mosquitoes by using the regional mosquito trapping network. 21

22 Appendix A Provincial Surveillance for West Nile Virus Case Definitions Provincial Surveillance for West Nile Virus (WNV) The current West Nile Virus Case definitions were updated in December Case definitions and diagnostic test criteria are subject to change as new information becomes available. West Nile Virus 1.0 Provincial Reporting Confirmed and probable cases of disease 2.0 Type of Surveillance Case-by-case 3.0 Case Classification 3.1 Confirmed WN virus Neurological Syndrome (WNNS) Case Clinical criteria AND AT LEAST ONE of the confirmed case diagnostic test criteria (See Section 4.1.1) 3.2 Probable WNNS Case Clinical criteria AND AT LEAST ONE of the probable case diagnostic test criteria (See Section 4.1.2) 3.3 Confirmed WN virus Non-Neurological Syndrome (WN Non-NS) Case Clinical criteria AND AT LEAST ONE of the confirmed case diagnostic test criteria (See Section 4.1.1) 3.4 Probable WN Non-NS Case Clinical criteria AND AT LEAST ONE of the probable case diagnostic test criteria (See Section 4.1.2) 22

23 3.5 Confirmed WN virus Asymptomatic Infection (WNAI) 1 Case Confirmed case diagnostic test criteria (See Section 4.1.1) IN THE ABSENCE of clinical criteria 3.6 Probable WNAI Case Probable case diagnostic test criteria (See Section 4.1.2) IN THE ABSENCE of clinical criteria 4.0 Laboratory Evidence 4.1 Laboratory Confirmation Any of the following will constitute a confirmed case of WN virus: Positive West Nile virus culture Positive for West Nile virus antigen in tissue Positive for West Nile virus-specific nucleic acid Positive for West Nile virus-specific antibody Diagnostic rise in West Nile virus antibody titre Confirmed Case Diagnostic Test Criteria Health units should use the Confirmed Case Diagnostic Test Criteria to confirm initial cases (locally acquired) in their area each year; for subsequent cases, health units may use the Probable Case Diagnostic Test Criteria to classify cases in their area as confirmed. AT LEAST ONE of the following: A significant (i.e., fourfold or greater) rise in WN virus neutralizing antibody titres (using a PRNT or other kind of neutralization assay) in paired acute and convalescent sera, or cerebrospinal fluid (CSF) OR Isolation of WN virus from, or demonstration of WN virus antigen or WN virus- specific genomic sequences in tissue, blood, CSF or other body fluids OR Demonstration of flavivirus antibodies in a single serum or CSF sample using a WN virus Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) 2, 3, confirmed by the detection of WN virus specific antibodies using a PRNT (acute or convalescent serum sample) OR 23

24 A significant (i.e., fourfold or greater) rise in flavivirus haemagglutination inhibition (HI) titres in paired acute and convalescent sera or demonstration of a seroconversion using a WN virus Immunoglobulin G (IgG) ELISA 2, 3 AND the detection of WN specific antibodies using a PRNT (acute or convalescent serum sample) Probable Case Diagnostic Test Criteria AT LEAST ONE of the following: Detection of flavivirus antibodies in a single serum or CSF sample using a WN virus IgM ELISA 2 without confirmatory neutralization serology (e.g., PRNT) OR A significant (i.e., fourfold or greater) rise in flavivirus HI titres in paired acute and convalescent sera or demonstration of a seroconversion using a WN virus IgG ELISA 2 OR A titre of > 1:320 in a single WN virus HI test, or an elevated titre in a WN virus IgG ELISA, with a confirmatory PRNT result [Note: A confirmatory PRNT or other kind of neutralization assay is not required in a health jurisdiction/authority where cases have already been confirmed in the current year] OR Demonstration of Japanese encephalitis (JE) serocomplex-specific genomic sequences in blood by nucleic acid amplification test (NAAT) screening on donor blood, by Blood Operators in Canada. 4.2 Approved/Validated Tests Standard culture for WN virus NAAT for WN virus WN virus antigen detection in tissue WN virus IgM antibody detection WN virus HI, PRNT and/or IgG/IgM immunoassays 4.3 Indications and Limitations Sensitivity of NAAT testing is approximately 50% when used on plasma / serum samples collected less than 8 days after symptom onset. 24

25 5.0 Clinical Evidence 5.1 West Nile virus Neurological Syndrome (WNNS) Clinical Criteria: History of exposure in an area where WN virus (WNV) activity is occurring 4 O R History of exposure to an alternative mode of transmission 5 AND Fever AND NEW ONSET OF AT LEAST ONE of the following: Encephalitis (acute signs of central or peripheral neurologic dysfunction), O R Viral meningitis (pleocytosis and signs of infection e.g., headache, nuchal rigidity) O R Acute flaccid paralysis (e.g., poliomyelitis-like syndrome or Guillain- Barré-like syndrome) 6 O R Movement disorders (e.g., tremor, myoclonus) O R Parkinsonism or Parkinsonia-like conditions (e.g., cogwheel rigidity, bradykinesia, postural instability) O R Other neurological syndromes 7 25

26 5.2 West Nile virus Non-Neurological Syndrome (WN Non-NS) Clinical Criteria: History of exposure in an area where WN virus (WNV) activity is occurring 4 O R History of exposure to an alternative mode of transmission 5 AND AT LEAST TWO of the following: 7 fever myalgia 8 arthralgia headache fatigue lymphadenopathy maculopapular rash 6.0 ICD Code(s) ICD 10 Code A Comments 1. This category includes asymptomatic blood donors whose blood is screened using a Nucleic Acid Amplification Test (NAAT), by Blood Operators (i.e. Canadian Blood Services or Hema-Quebec) and is subsequently brought to the attention of public health officials. The NAAT that is currently used by Blood Operators in Canada is designed to detect all viruses in the Japanese encephalitis (JE) serocomplex. The JE serocomplex includes WN virus and nine other viruses, although from this group only WN virus and St Louis encephalitis virus are currently endemic to parts of North America. Blood Operators in Canada perform a supplementary WN virus-specific antibody (IgM and IgG) testing following any positive donor screen test result. The NAAT test used by Blood Operators is not approved for clinical diagnostic testing but can be used for surveillance case classifications. 2. Both CDC and commercial IgM / IgG ELISAs are now available for front line serological testing. Refer to appropriate assay procedures and kit inserts for the interpretation of test results. Due to high serological cross reactivity among flaviviruses, travel history should be obtained to determine if other flaviviruses should be tested for (e.g. Dengue virus, St. Louis Encephalitis and Japanese Encephalitis). 26

27 3. Early in infection the immune system generates antibodies that bind relatively weakly to viral antigen (low avidity). As the infection proceeds, an increasing percentage of newly generated IgG antibody displays higher binding affinity to virus antigen and thus avidity also rises (Note: avidity is usually measured based upon the ability of IgG to dissociate from antigen preparations after incubation with a solution of urea). As long as high avidity IgG is not yet detected in the serum it can be assumed that the individual was exposed to the viral agent during a recent exposure. With respect to WNV infection it has not been precisely determined when (i.e. post-exposure) high avidity antibodies reach levels in serum that can be accurately detected by serological assays (there may be significant variation depending on the individual). However, it has been shown that >95% of sera collected from individuals exposed to WNV 6-8 months previously will have IgG antibodies that bind strongly to viral antigen and will give high avidity scores using both indirect fluorescent antibody (IFA) and ELISA testing formats. Note: Avidity testing will not replace confirmatory neutralization testing, non-wnv flavivirus IgG antibody (e.g., dengue, St Louis encephalitis [SLE]) may bind to the antigen preparations usedin avidity assays. Note: WNV IgM antibody may persist for more than a year and the demonstration of IgM antibodies in a patient s serum, particularly in residents of endemic areas, may not be diagnostic of an acute WN viral infection. Seroconversion (by HI, IgG ELISA or PRNT assays) demonstrates a current WNV infection. Therefore, the collection of acute and convalescent sera for serologic analysis is particularly important to rule out diagnostic misinterpretation early in the WNV season (e.g. May, June) and to identify initial cases in a specific jurisdiction. However, it should be noted that seroconversions may not always be documented due to timing of acute sample collection (i.e. titres in acute sera may have already peaked). If static titres are observed in acute and convalescent paired sera, it is still possible the case may represent a recent infection. To help resolve this, the use of IgG avidity testing may be considered to distinguish between current and past infection. The presence of both IgM antibody and low avidity IgG in a patient s convalescent serum sample are consistent with current cases of viral associated illness. However test results that show the presence of IgM and high avidity IgG are indicative of exposures that have occurred in a previous season. Immunocompromised individuals may not be able to mount an immune response necessary for a serological diagnosis. West Nile virus diagnostic test criteria for these individuals should be discussed with a medical microbiologist. 4. History of exposure when and where West Nile virus transmission is present, or could be present, or history of travel to an area with confirmed WNV activity in mosquitoes, birds, horses, other mammals or humans. 5. Alternative modes of transmission, identified to date, include: laboratoryacquired; in utero; receipt of blood components; organ/tissue transplant; and, possibly via breast milk. 27

28 6. A person with WNV-associated acute flaccid paralysis may present with or without fever or mental status changes. Altered mental status could range from confusion to coma with or without additional signs of brain dysfunction (e.g. paralysis, cranial nerve palsies, sensory deficits, abnormal reflexes, generalized convulsions and abnormal movements). Acute flaccid paralysis with respiratory failure is also a problem. Note: A significant feature of West Nile virus neurological illness may be marked muscle weakness that is more frequently unilateral, but could be bilateral. WNV should be considered in the differential diagnosis of all suspected cases of acute flaccid paralysis with or without sensory deficit. WNV- associated weakness typically affects one or more limbs (sometimes affecting one limb only). Muscle weakness may be the sole presenting feature of WNV illness (in the absence of other neurologic features) or may develop in the setting of fever, altered reflexes, meningitis or encephalitis. Weakness typically develops early in the course of clinical infection. Patients should be carefully monitored for evolving weakness and in particular for acute neuromuscular respiratory failure, which is a severe manifestation associated with high morbidity and mortality. For the purpose of WNV Neurological Syndrome Classification, muscle weakness is characterized by severe (polio-like), non-transient and prolonged symptoms. Electromyography (EMG) and lumbar puncture should be performed to differentiate WNV paralysis from the acute demyelinating polyneuropathy (Guillain-Barré syndrome). Lymphocytic pleocytosis (an increase in WBC with a predominance of lymphocytes in the cerebrospinal fluid [CSF]) is commonly seen in acute flaccid paralysis due to WNV. Other emerging clinical syndromes, identified in 2002 included, but were not limited to the following: myelopathy, rhabdomyolysis (acute destruction of skeletal muscle cells), peripheral neuropathy; polyradiculoneuropathy; optic neuritis; and acute demyelinating encephalomyelitis. Ophthalmologic conditions including chorioretinitis and vitritis were also reported. Facial weakness was also reported. Myocarditis, pancreatitis and fulminant hepatitis have not been identified in North America, but were reported in outbreaks of WNV in South Africa. Aseptic meningitis without encephalitis or flaccid paralysis occurring in August and September when WNV is circulating may be due to non-polio enteroviruses circulating at the same time. This should be considered in the differential diagnosis. 7. It is possible that other clinical signs and symptoms could be identified that have not been listed and may accompany probable case or confirmed case diagnostic test criteria. For example, gastrointestinal (GI) symptoms were seen in many WNV patients in Canada and the USA in 2003 and Muscle weakness may be a presenting feature of WNV illness. For the purpose of WNV Non-Neurological Syndrome classification, muscle weakness or myalgia (muscle aches and pains) is characterized by mild, transient, unlikely prolonged symptoms that are not caused by motor neuropathy. 28