Chair and members of the Board of Health

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1 2016 West Nile Virus Summary TO: Chair and members of the Board of Health MEETING DATE: June 7, 2017 REPORT NO: BH.01.JUN0717.R16 Pages: 15 Leslie Binnington, Health Promotion Specialist, Health Analytics; PREPARED BY: Mike Coburn, Public Health Inspector, Environmental Health; and Shawn Zentner, Manager, Environmental Health APPROVED BY: SUBMITTED BY: Christopher Beveridge, Director, Health Protection Original signed document on file Dr. Nicola J. Mercer, MD, MBA, MPH, FRCPC Medical Officer of Health & CEO Recommendations It is recommended that the Board of Health: 1. Receive this report for information. Key Points In 2016, Wellington-Dufferin-Guelph Public Health (WDGPH) implemented its 14 th consecutive West Nile Virus (WNV) prevention program. The goal of this program is to prevent or reduce human exposure to WNV through public education, larval and adult mosquito surveillance and larviciding activities. Larval surveillance, catch basin and surface water treatments, live adult mosquito trapping, and standing water complaints outside of the City of Guelph were conducted by the Canadian Centre for Mosquito Management Inc. (CCMM) as contracted by WDGPH. Surveillance for mosquito larvae in catch basins and surface waters began in early May 2016 until late September Adult mosquito trapping and surveillance began in June 2016 and continued until September Adult mosquito identification and viral-testing was conducted by Entomogen Inc. The City of Guelph s Property Standards Inspection Department addressed 23 standing water complaints. Outside of the City of Guelph, CCMM addressed only two (2) complaints by citizens regarding standing water.

2 In 2016, one (1) human case of WNV was confirmed within the borders of WDGPH, which represented an incidence rate of 0.3 cases per 100,000 people. This case is thought to have been acquired locally. Public education in 2016 included communicating key messages to: prevent mosquito bites, eliminate standing water on property to reduce mosquito breeding grounds, and public encouragement to call Public Health for free larvicide treatment for municipally-owned catch basins (storm drains) on their property through online and print materials. Discussion WNV is transmitted from mosquitoes to humans and was first found in Ontario in Birds of the Corvid family (crows, ravens and blue jays) act as the primary reservoir for the virus, and mosquitoes are the vectors that spread the virus from infected birds to humans and to other animals. 1 Among large animals, horses are especially at risk for WNV infection and disease. 1,2 The mosquito species of greatest concern for the transmission of WNV are Culex restuans and Culex pipiens. 3 These mosquitoes thrive in urban environments where they breed in small bodies of protected, stagnant water as found in catch basins, abandoned swimming pools, old tires, blocked eaves troughs, storm retention ponds, and bird baths. Health Effects of WNV It is estimated that between 70% 80% of people infected with WNV have no symptoms. 4,5 Some people will experience mild, flu-like symptoms including fever, headache, body aches, mild rash, and swollen lymph glands. 5,6 In rare cases (<1%) the virus can cause severe symptoms such as inflammation of the brain or spinal cord, which can sometimes be fatal. 7 In general, recovery can take a week for mild cases, and months to years for more severe cases. People over age 50, who have chronic diseases such as cancer, diabetes, alcoholism, or heart disease, or who are immunocompromised, are at higher risk for serious health effects. However, WNV can cause severe complications for people of any age or health status. 1 It is important to note that there is no specific treatment or vaccine for WNV infection in humans, however, mild symptoms such as fever and body aches can be managed and treated. WNV in WDG and Ontario WNV activity was first reported in Canada in the summer of 2001 when the virus was found in dead birds and mosquito pools in southern Ontario. In 2002, the first human cases of WNV were reported in Ontario and Quebec. Throughout 2002, 395 cases of WNV were reported in Ontario. From 2003 through 2011, the number of cases reported annually remained relatively low, ranging from 4 to 101, until 2012 when 271 confirmed human cases of WNV were reported in Ontario. Since that time, infection rates have fluctuated in Wellington-Dufferin-Guelph while Ontario rates have increased since 2014 as illustrated in Appendix A. Page 2 of 15

3 In 2016, one (1) human case of WNV was confirmed within the borders of WDGPH, which represents an incidence rate of 0.3 cases of WNV per 100,000 people. This case of labconfirmed WNV is thought to have been acquired within the borders of WDGPH as the patient had no travel history. In comparison, the incidence rate for Ontario in 2016 was 0.4 cases per 100,000 people (case count: 55). WDGPH s Prevention Program WDGPH s WNV prevention program dates back to 2002 when the first human case from within the health unit was reported. The program typically runs from May/June to September/October of each year depending on weather conditions, when mosquitoes are most prevalent and the potential for infection is highest. 8 The purpose of the WNV program is to prevent or reduce human exposure to WNV within the community through larviciding, mosquito surveillance and public education. These program components remain similar from one year to the next, and can be scaled up or down as needed based on the surveillance being conducted. Adulticiding is not part of WDGPH s WNV program. This program operates in accordance with the Ministry s West Nile Virus Preparedness and Prevention Plan. A summary of WDGPH s prevention program can be found in Appendix B. Larvicide Program The larvicide program involves larval surveillance, catch basin (storm drain) and surface water treatment, live adult mosquito trapping and addressing standing water complaints, conducted by the Canadian Centre for Mosquito Management Inc. (CCMM). Standing water within the borders of the City of Guelph were addressed through the City of Guelph s Standing Water By-law (Bylaw Number (2003) 1719) by the City of Guelph s Property Standards Inspection Department, often in conjunction with WDGPH. In mid-may, 2016, a Public Notification was placed in local newspapers more than two weeks before larviciding treatments began (Appendix C ). Public notification is a mandatory requirement of the Ministry of the Environment and Climate Change. Besides being notified of upcoming treatments, the public was also encouraged to have catch basins located on their own properties treated. The larviciding service was offered free-of-charge and promoted through a media release and the WDGPH website, where a request form/waiver was made available for download and printing. In addition, letters were sent to homeowners who had catch basins treated in previous years saw a slight drop in the number of treatment requests to 140 requests in 2016 from 150 in Surveillance for mosquito larvae in catch basins began in early May Catch basins are designed to trap water and sometimes this water remains stagnant for an extended period of time creating ideal conditions for mosquito breeding. It is widely acknowledged that catch basins provide the single most important developmental site for urban Culex populations of mosquitoes, the primary vectors of WNV. Therefore, timely application of larvicides to catch basins is critical to the success of a municipal WNV management program. Once it was established that the vector species for WNV, Culex Pipiens and Culex restuans, were present, catch basin treatments began on June 10, 2016 and concluded on August 11, Details regarding CCMM s larviciding program can be found in Appendix D. Page 3 of 15

4 The public was encouraged to notify WDGPH of areas of standing water that may be conducive to mosquito-breeding. A total of 23 standing water complaints were addressed by the City of Guelph s Property Standards Inspection Department, the majority concerning swimming pools on private property that were not being maintained. Enforcement of this by-law commenced and concluded based on larval and adult mosquito activity determined through surveillance. Only two (2) complaints regarding standing water were registered outside the borders of the City of Guelph. Both resulted in surface water treatments by CCMM. Surveillance Surveillance activities included the collection of both adult and larval life stages of the vector species, Culex restuans and Culex pipiens. The presence of larval vector species determined whether or not the standing water in question would be treated. Trapped adults were sent to Entomgen Inc. for species identification. Positively identified vector species were tested for the presence of WNV in order to determine the prevalence of the virus in mosquitoes in the WDGPH area. A summary of surveillance activities and findings can be found in Appendix E. Despite an increase in the human infection rate in 2016 compared to 2015, the overall number of vector species, as well as positive mosquito pools, has been in steady decline or zero (0) since 2014 (Appendix F ). In fact, the overall number of mosquitoes captured and submitted was greatly reduced in 2016 from previous years. This may be attributed to several factors including successful ongoing control measures and increased public awareness through public health education and communications. Environmental factors, particularly reduced rainfall in 2016, likely also played an important role in the nearly 50% decrease in the amount of surface waters which were treated by CCMM during the 2016 season (from 6.64 hectares of surface area treated in 2015 to hectares in 2016). Public Education Public education efforts continued in 2016 to convey that WNV is still a concern, regardless of weather conditions, and that simple steps can be taken by the public to reduce their risk of contracting the virus. Key messages included steps to prevent mosquito bites, to eliminate standing water on property to reduce mosquito breeding grounds, and public encouragement to contact Public Health for free larvicide treatment for municipally-owned catch basins (storm drains) on their property. Key messages were delivered through: A media release was distributed on May 10, This media release was picked up by The Wellington Advertiser, CJOY 1460, and Magic 106.1FM. Shawn Zentner was also featured in an interview with MyFM. An article was subsequently published on OrangevilleToday.ca. WDGPH WNV webpage was updated and had 217 unique page views throughout WDGPH s blog post Fight the Bite featured an article on WNV and was posted on May 10, This blog had 128 unique page views. Key messages were tweeted and posted on Facebook in spring and summer An article about WNV was featured in the June edition of the One Health e-newsletter that is sent to veterinarians in WDG. This newsletter was opened by 52% of recipients (55/106). Page 4 of 15

5 WDGPH Strategic Direction(s) WNV exists in Wellington-Dufferin-Guelph and will continue to be a presence in the future as long as there are Corvid birds to act as reservoirs for the virus and mosquito vectors to transmit the virus to humans. A lack of rainfall in 2016 may have decreased the number of vector species, Culex pipiens and Culex restuans, and may have helped keep the number of positive mosquito pools at zero, yet WDGPH still had one reported human case of WNV. This, as well as the 2012 increase in WNV cases across the province, should serve as a reminder that it is difficult to predict virus activity from one year to the next, as it is dependent on many different factors. Thus, vigilant surveillance, larviciding, and educational efforts in 2017 and beyond is important. Ontario Public Health Standard Health Hazard Prevention and Management Program Standard Goal: To prevent or reduce the burden of illness from health hazards in the physical environment. The board of health shall develop a local vector-borne management strategy based on surveillance data and emerging trends in accordance with the Infectious Diseases Protocol, WDGPH Strategic Direction(s) Check all that apply: Health Equity We will provide programs and services that integrate health equity principles to reduce or eliminate health differences between population groups. Organizational Capacity We will improve our capacity to effectively deliver public health programs and services. Service Centred Approach We are committed to providing excellent service to anyone interacting with Public Health. Building Healthy Communities We will work with communities to support the health and well-being of everyone. Health Equity A higher prevalence of WNV has been found in both mosquitos and humans in low-income areas. The environmental characteristics of low-income areas can be conducive for mosquito 9, 10 development, potentially leading to a higher occurrence of WNV disease in humans. Page 5 of 15

6 WNV prevalence in low income areas is thought to occur due to a combination of three factors: 1. Older infrastructure characterized by antiquated runoff systems that contribute to poor drainage and favourable mosquito breeding habitats; 2. Less likelihood of investment in private property upkeep, leading to a higher density of stagnant water; and 3. Less education and political involvement, with a lower likelihood of requesting mosquito management in the area. 9 Appendices Appendix A WNV Rates in WDGPH and Ontario (10 year trend) Appendix B Infographic: Summary of WDGPH s 2016 WNV Program Appendix C - Larvicide Public Notice Appendix D Summary of CCMM s Larval Mosquito Control Program (Larviciding) Appendix E - Summary of WNV Surveillance Activities Appendix F - Summary of WNV Vector Surveillance and Testing References 1. Health Canada. [Internet]. Surveillance of West Nile virus. [updated 2016, Dec 02; cited 2017 May 11]. Available from 2. Centers for Disease Control and Prevention. [Internet]. West Nile Virus in the United States: Guidelines for Surveillance, Prevention, and Control. 4 th Revision. [updated 2013 June 14; cited 2017 May 11]. Available from: 3. Public Health Ontario. [Internet]. Guide for Public Health Units: Considerations for Adult Mosquito Control Guidance Document. [updated 2013 Aug; cited May]. 4. Mostashari F, Bunning M, Kitsutari P et al. Epidemic West Nile encephalitis, New York, 1999: Results of a household-based seroepidemiological survey. Lancet. 2001; 358: Zou S, Foster GA, Dodd RY et al. West Nile fever characteristics among viremic persons identified through blood donor screening. J Inf Dis. 2010; 202: Watson J, Pertel P, Jones R et al. Clinical characteristics and functional outcomes of West Nile Fever. Ann Intern Med. 2004; 141: Page 6 of 15

7 7. Hayes E, Sejvar J, Zaki S, Lanciotti R, Bode A, Campbell G. Virology, pathology, and clinical manifestations for West Nile Virus Disease. Emerg Infect Dis. 2005; 11: Ontario Ministry of Health and Long-Term Care. West Nile Virus Preparedness and Prevention Plan Toronto ON: Queen s Printer for Ontario. 9. Harrigan R, Thomassen H, Beurmann W et al. Economic Conditions Predict Prevalence of West Nile Virus. PLoS ONE. 2010; 5(11): e LaDeau SL, Liesnham PT, Biehler D, Bodner D. Higher mosquito production in low-income neighbourhoods of Baltimore and Washington, DC: Understanding ecological drivers and mosquito-borne disease risk in temperate cities. Int J Environ Res Public Health. 2013; 10(4): Page 7 of 15

8 APPENDIX A Figure 1: Incidence Rates of West Nile Virus* in WDG and Ontario - 10-year Trend Number of cases per 100,000 people WDG rate ON rate Year of Case Onset *lab-confirmed and probable cases. Data source: iphis, Case counts and crude rates of reportable diseases by year. Date extracted: May 9, 2017 Page 8 of 15

9 APPENDIX B Figure 1: Summary of WDGPH s 2016 West Nile Virus Program Page 9 of 15

10 APPENDIX C Figure 1: Larvicide Public Notice Page 10 of 15

11 APPENDIX D Summary of CCMM s Larval Mosquito Control Program (Larviciding) Figure 1: Summary of Types of Treatment Locations 2016 Summary of Types of Treatment Locations in WDG (2016) (Per Round of Treatment) Location Type Total (Per Round) Roadside Catch Basins 22,284 Non-Roadside Catch Basins 140 Environmentally Sensitive (ESA) Area Catch 25 Basins Stagnant Surface Waters Ditches x 48 Storm Management Ponds x 39 Woodland Pools x 6 Storm Management Ditches x 6 Ponds x 1 Naturalization Areas x Ha (Total Surface Area) Figure 2: Summary of Non-ESA Catch Basin Larvicide Treatments 2016 Summary of Non-ESA Catch Basin Larvicide Treatments in WDG (2016) Product Rounds App. Rate CBs Treated/Round Total Prod. Used All Rounds Altosid Pellets g/cb 22, kg Altosid XR Briquets 1 1 Briquet/CB Briquets Figure 3: Summary of ESA Catch Basin Larvicide Treatments 2016 Summary of ESA Catch Basin Larvicide Treatments in WDG (2016) Product Rounds App. Rate CBs Treated/Round Total Prod. Used All Rounds VectoLex WSP 4 1 Pouch/CB Pouches Page 11 of 15

12 APPENDIX D (continued) Figure 4: Summary of Stagnant Surface Water Larvicide Treatment 2016 Summary of Stagnant Surface Water Larvicide Treatments in WDG (2016) Product Total Treatments App. Rate VectoBac 200G kg/ha Area Treated Total Prod. Used All Treatments ha kg Figure 5: Summary of Larvicide Application Dates 2016 Summary of Larvicide Application Dates in WDG (2016) App. App. #3 App. #2 #4 Site Product App. #1 Roadside CBs Nonroadside CBs Altosid Pellets Altosid XR Briquets June June 24, July 6, 15 & 22 June 28 July 1 July 19 & 20 Aug. 10 & 11 Unscheduled Apps. N/A N/A N/A N/A N/A ESA CBs VectoLex WSP June 10 July 1 July 22 Aug. 11 Stagnant Surface Waters VectoBac 200G N/A N/A N/A N/A N/A May 26 September 30 Page 12 of 15

13 APPENDIX D (continued) Figure 6: Summary of Product Application Locations in WDG 2016 Wellington-Dufferin-Guelph Public Health Vector-borne Disease Summary of Product Application Location by Community 2016 Roadside (Non- ESA) Catch Basins Treated w/ Altosid Pellets Non-Roadside (Non-ESA) Catch Basins Treated with Altosid XR Briquets ESA CBs w/ Vectolex WSP Stagnant Surface Waters w/ Vectobac 200G Guelph Guelph Guelph Guelph Guelph-Eramosa Orangeville Guelph-Eramosa Rockwood Puslinch Rockwood Erin Orangeville Erin - Orangeville Fergus Orangeville - - East Garafraxa Palmerston - - Arthur Mount Forest Harriston Fergus Elora Drayton Arthur Page 13 of 15

14 APPENDIX E Figure 1: Summary of WNV Surveillance Activities Wellington-Dufferin-Guelph Public Health Vector-borne Disease Summary of Adult Mosquito Species Surveillance 2016 Vector Species Species Identified Total Number Overall % Culex pipiens/restuans % Culex species % Bridge Vector Species Ochlerotatus stimulans % Ochlerotatus canadensis % Aedes vexans vexans % Anopheles quadrimaculatus % Ochlerotatus triseriatus % Anopheles punctipennis % Anopheles walkeri % Ochlerotatus trivittatus % Non-Bridge Vector Species Coquillettidia perturbans % Ochlerotatus broad-banded % Ochlerotatus black-legged % Aedes cinereus % Aedes/Ochlerotatus species % Aedes vexans/cantator % Anopheles earlei % Culiseta minnesotae % Ochlerotatus excrucians % Anopheles species % TOTAL % Page 14 of 15

15 APPENDIX F Figure 1: Summary of WNV Vector Surveillance and Testing Summary of WNV Vector Surveillance & Testing ( ) Year Culex Culex sp. Culex salinarius Positive Pools pipiens/restuans (29.42% of total) 2 (0.09% of total) (19.65% of total) 3 (0.04% of total) 3 (0.04% of total) (6.23% of total) (4.93% of total) (1.35% of total) 1 (0.07% of total) - 0 Page 15 of 15