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Lyme disease in Ontario: Generating and Using Evidence to Inform Decision Making
https://www.msu.edu/course/isb/202/ebertmay/images/Deertick%20Female.jpg
Nina Jain‐Sheehan
Enteric, Zoonotic and Vector‐Borne Diseases
Objectives and Outline
Objectives:
•Describe the emerging epidemiology of Lyme disease in Ontario
•Provide an understanding of Ontario’s existing Lyme disease
surveillance
•Outline some of Ontario’s plans for improved surveillance and risk
communication based on our understanding of the emerging
epidemiology
Outline:
•Human Epidemiology
•Tick Surveillance•Lyme disease Risk Maps
•Lyme disease Initiatives
2
The blacklegged tick (Ixodes
scapularis) is the vector responsible
for transmitting Lyme disease (LD) in
Ontario
R. Lindsay PHAC
Tick Habitat
www.cdc.gov
From: IDSA Guidelines – CID 2006:43 (1 November)
Ontario Lyme disease History
• In 1991 only one population of ticks that carry Lyme disease (LD) was known in
Canada. It was located in Ontario at Long Point Provincial Park.
• Since then the following areas were identified:• Turkey Point Provincial Park• Rondeau Provincial Park• Point Pelee National Park• Prince Edward Point National Wildlife Area
• In 2006 the Ministry of Health and Long‐Term Care participated in tick surveillance
studies with the Public Health Agency of Canada and discovered an new endemic
area in St. Lawrence Islands National Park area
• The Ministry started to do active tick surveillance in 2007.
• Since then the following areas have been identified as endemic:• Wainfleet Bog• Rainy River
Ontario Lyme Disease Endemic Locations
9
Number of Reported Confirmed and
Probable Human Lyme Disease Cases and
Rate (per 100,000 population) by Year,
Ontario, 2002 to 2013
Data Source: Ontario Ministry of Health and Long‐Term Care, integrated Public Health Information System (iPHIS) database, extracted by Public Health Ontario [2014/02/04] Population estimates (for rate calculations): Ontario Ministry of Health and Long‐term Care, IntelliHEALTH Ontario, extracted by Public Health Ontario [2013/09/16]. Notes: Population estimates for 2012 were used to estimate provincial population counts for 2013Data from 2009 onwards includes both confirmed and probable cases. The Lyme Disease confirmed case definition changed in 2009 such that clinical cases were no longer
considered confirmed. Clinical cases are now considered probable cases and case counts for 2009 and subsequent years include both confirmed and probable cases to
ensure valid comparisons of trends over time.
10
Number of Cases and Incidence Rate of
Lyme Disease by Age and Gender, Ontario,
2013
11
Case counts include probable and confirmed casesCases: Ontario Ministry of Health and Long‐Term Care, integrated Public Health Information System (iPHIS) database, extracted by Public Health Ontario [2014/02/04].Population estimates (for rate calculations): Ontario Ministry of Health and Long‐term Care, IntelliHEALTH Ontario, extracted by Public Health Ontario [2013/09/16].
Number of Lyme Disease Cases by Episode Month, Ontario, 2013
12
Note: Episode date is the first of onset date, specimen collection date, or case report date.Case counts include probable and confirmed casesData source: Ontario Ministry of Health and Long‐Term Care, integrated Public Health Information System (iPHIS) database, extracted by Public Health
Ontario [2014/02/04].
Number and Proportion of Lyme Disease Cases Reporting Select
Symptoms, Ontario, 2013.
13
Note: Only select symptoms are shown. Cases can report multiple symptoms.Case counts include probable and confirmed casesData source: Ontario Ministry of Health and Long‐Term Care, integrated Public Health Information System (iPHIS) database,
extracted by Public Health Ontario [2014/02/04]
Symptom Count (n) Proportion (%)
AV Heart Block 2 0.63
Bells Palsy 25 7.89
Erythema Migrans 178 56.15
Municipalities Identified as the Most Likely Exposure
Location for Locally Acquired Lyme disease Cases:
Ontario, 2013
Data source: Ontario Ministry of Health and Long‐Term Care, integrated Public Health Information System (iPHIS) database, extracted
by Public Health Ontario [2014/02/19]. Case counts include probable and confirmed cases
14
Health unit Confirmed Probable Total Rate (per 100,000)*
Leeds, Grenville, and Lanark District 24 21 45 26.58
Kingston‐Frontenac and Lennox and Addington 37 14 51 25.75
Eastern Ontario 9 20 29 14.41
Hastings and Prince Edward Counties 10 6 16 9.90
City of Ottawa 12 34 46 5.00
Chatham‐Kent 4 1 5 4.61
Peterborough County‐City 1 4 5 3.58
Haliburton‐Kawartha‐Pine Ridge District 2 4 6 3.34
Haldimand‐Norfolk 3 0 3 2.72
Renfrew County and District 2 0 2 1.93
Durham Regional 7 5 12 1.88
Grey‐Bruce 3 0 3 1.83
Huron County 1 0 1 1.65
York Regional 12 5 17 1.57
Lambton 2 0 2 1.53
Wellington‐Dufferin‐Guelph 2 2 4 1.43
Waterloo 6 1 7 1.30
Perth District 1 0 1 1.30
Halton Regional 3 3 6 1.14
Niagara Regional Area 5 0 5 1.12
City of Toronto 22 7 29 1.04
Ontario 183 134 317 2.35
Number and Incidence Rate of Reported
Confirmed and Probable Lyme disease Cases
by Health Unit of Residence, 2013
Data source: Lyme disease cases: Ontario Ministry of Health and Long‐term Care, integrated Public Health Information System (iPHIS) database, extracted by Public Health Ontario [2014/02/04]. Population estimates (for rate calculations): Ontario Ministry of Health and Long‐term Care, IntelliHEALTH Ontario, extracted by Public Health Ontario [2013/09/16]. NOTE: Population counts for 2012are used to
estimate health unit and provincial population counts for 2013.
15
Number and Incidence Rate of Reported
Confirmed and Probable Lyme disease
Cases by Health Unit of Residence, 2008
16
Health Unit Confirmed Probable Total Rate (per 100,000)*Leeds, Grenville, and Lanark District 13 0 13 7.73Northwestern 3 2 5 6.08Haldimand‐Norfolk 4 0 4 3.6Brant County 4 0 4 2.87Timiskaming 1 0 1 2.87
Kingston‐Frontenac and Lennox and Addington 2 2 4 2.06Halton Regional 5 4 9 1.82Peterborough County‐City 1 1 2 1.44Perth District 1 0 1 1.29Hastings and Prince Edward Counties 2 0 2 1.23Simcoe Muskoka District 4 1 5 0.97Peel Region 6 6 12 0.92Niagara Regional Area 4 0 4 0.9Algoma District 1 0 1 0.84Hamilton, City of 4 0 4 0.75City of Ottawa 5 1 6 0.68Thunder Bay District 1 0 1 0.64Toronto 11 4 15 0.56Haliburton‐Kawartha‐Pine Ridge District 1 0 1 0.56York Region 3 1 4 0.39Windsor‐Essex County 0 1 1 0.25Middlesex‐London 1 0 1 0.22Waterloo Region 1 0 1 0.19Durham Regional 1 0 1 0.16Ontario 79 23 102 1.63
Data source: Lyme disease cases: Ontario Ministry of Health and Long‐term Care, integrated Public Health Information System (iPHIS) database, extracted by Public Health Ontario [2014/03/10]. Population estimates (for rate calculations): Ontario Ministry of Health and Long‐term Care, IntelliHEALTH Ontario, extracted by Public Health Ontario [2013/09/16].
Standardized Questionnaire
17
• LD cases have increased in Ontario over the past few years.
• Ontario’s 36 Health Units currently use a variety of questionnaires to interview cases and collect epidemiological
data
• To better inform clinical and public health decision making we
need to collect standardized information from cases.
• Developing a standardized questionnaire will help to generate higher quality and more consistent information on LD cases.
• Main goal is to obtain better exposure location data.
• Exploring ways of standardizing how exposure location data is collected and reported.
Objectives of Tick Surveillance
• Establish presence/geographic distribution of LD vector, Ixodes scapularis.
• Differentiate adventitious ticks vs. established populations.
• Size/density of vector populations.
• Prevalence of B. burgdorferi
infection.
• Infer risk of exposure based on the above factors and intensity of human use of habitat/opportunity for exposure to infected vectors.
• Implement measures to mitigate risk of exposure & subsequent
infection and disease.
• The prevalence of B. burgdorferi
and other tick‐borne illnesses will help to
guide clinical and public health decision making.
Lyme Disease Vector Surveillance in Ontario
Passive Surveillance•
Ticks are submitted by the public
•
Confirmed human cases
Active Surveillance•
Go out into the environment to look for the ticks
•
Tick dragging
•
Small mammal trapping
Passive Tick Surveillance
20
• Identification to species• Stage, engorgement, sex• Borrelia and Anaplasma testing
Ixodes scapularis
National Microbiology Laboratory Public Health Ontario Laboratory
Data collection: reporting, analyses, hypotheses testing
HEALTH UNIT
www.the color.com LRL
Drag Sampling
Small Mammal Trapping
Public Health Ontario Tick Submissions
23
Species Distribution of Submitted Ticks (2013)
24
BLT Engorgement and Attachment Status and B. burgdorferi Positivity (2008‐2012)
Engorgement and
attachment statusTotal positive pools/total pools tested (%)
Total (avg %)
Adults Nymphs
Engorged + attached146/1,991 (7.3) 18/130 (13.8) 164/2,121 (7.7)
Unengorged + attached718/3,712 (19.3) 14/153 (9.2) 732/3,865 (18.9)
Unengorged + unattached9/60 (15.0) NT† 9/60 (15.0)
Total (average %) 873/5,763 (15.1) 32/283 (11.3) 905/6,046 (15.0)
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The age of submitters of BLTs that were engorged (45.2 ± 0.80 y) was significantly higher than
those submitting BLTs that were unengorged (40.5 ±
0.54 y) (F1,2790
= 24.6; p<0.0001).
Age distribution of Ixodes scapularis
submitters (2008–2012).
26
The Location and Number of I. scapularis Submitted
to PHO, Based on the Submitter’s Community of
Residence: Ontario, 2013
Data source:
Public Health Ontario (PHO), extracted [2014/03/12]27
The Location and Number of I. scapularis Submitted
to Public Health Ontario, Based on the Submitter’s
Community of Residence: Ontario, 2008‐2013
28
Percentage B. burgdorferi‐positivity and
Total I. scapularis
by Submitter Town of
Exposure (2008–2012)
Data source: PHAC, extracted [2014/03/12]29
Atlas of Canada Land Cover
30http://atlas.gc.ca/data/english/maps/forestry/land_cover_map.pdf
Ontario Percent Forest Cover
31https://nfi.nfis.org/forest_themes.php?lang=en
www.oahpp.ca
Rate of I. scapularis Spread
32
Trends in the Infection Prevalence of B. burgdorferi 2008–2012
33
*Dotted lines: simple linear regressions for percentage of BLTs
pools positive for B. burgdorferi. •B.
burgdorferi, y = 2.5x + 5.6; R²
= 0.96 (F1,3
= 75.4; p =
0.003)
B. Burgdorferi Infection Prevalence in ticks: Comparisons to Literature
• The overall prevalence of B. burgdorferi infection in
Ontario BLTs was 15%
• Emerging areas:• Manitoba (10%)• Quebec (13%)• Nova Scotia (15%)
• Long‐established areas:• Hudson Valley, NY (49–65%)• New Jersey (49%)• Long Point, Ontario (67%)
34
10% 13% 15%
15%
49%49‐65%
67%
Ogden NH, et al. (2006) Int J Parasitol 36: 63‐70; Ogden NH, et al. (2006) J Med Entomol 43: 600‐609; Schulze TL, et al. (2003) J Med
Entomol 40: 555‐558; Magnarelli LA, et al. (1986) J Wildl Dis 22: 178‐188; Lindsay LR, et al. (1999) J Med Entomol 36: 243‐254.
Summary of Tick Data
• I. scapularis is now the most abundant tick submitted in ON
• Eastern region reported the highest submission rates for BLTs
• Coincide with higher rates of Lyme disease
• Land use and temperature possible driving factors; increased awareness
• Children 0–9 yo & adults 55–74 yo have highest submission rates for BLTs;
engorged BLTs more often submitted from older individuals; males
submitted more BLTs
• Due to variable exposure to tick habitats, host behaviors or tick submission efforts?
• Opportunity for targeted education
• Proportion of BLTs
infected with B.
burgdorferi
has increased in Ontario
(2008‐2012)
• Continued increase expected for next few years until equilibrium established
Implications of Data
• Utility of passive surveillance limited to regions of the
province with a high population density• Sparsely populated Northern areas will rely on human case detection,
small mammal trapping, and tick dragging
• Better to concentrate efforts on active tick dragging in known risk areas and passive from low risk/unknown areas
36
Three tiers of Tick Submissions1.Active surveillance only for endemic/high
submission areas
2.Passive outside of endemic areas
3.Continue passive submissions in the rest of the
province
Proposed Changes for tick surveillance activities
37
Preliminary Lyme disease Risk Maps
38
Data Elements:•Endemic Locations•Human Cases (most
likely exposure•Tick submissions (most
likely acquisition)•Tick positivity•Active Drag Sites
Ecological Factors Facilitating Tick Expansion
• Conducting a literature review identifying the abiotic and biotic factors required for tick establishment
• Focusing on evidence from North America, particularly
northcentral and northeastern United States, and
Ontario/Quebec
• Primary risk to ticks is desiccation
• Future steps:• Identify distribution of these requirements in Ontario
• Map out likely environments for tick establishment
39
Literature Review Preliminary Results
40
• Factors influencing distribution and expansion of I. scapularis:
41
Provincial Lyme disease Awareness Campaign (Ministry of
Health and Long‐Term Care)
www.ontario.ca/lyme
Conclusions
• Lyme disease epidemiology continues to evolve in Ontario
• Our understanding of current and future risk is improving
• Based on existing evidence we are undertaking several initiatives to further improve our understanding and risk communication related
to Lyme disease in Ontario. Specifically:• Standardized case questionnaires• Refinements to Ontario’s tick surveillance• Production of risk maps for use by physicians and public health partners• Reviewing evidence on tick expansion to inform future plans and activities
• We will continue to adjust and improve our approaches to provide
the most relevant scientific and technical support possible given the
available and emerging evidence.
43
Acknowledgments
• Ontario’s 36 Public Health Units• Public Health Ontario:
• Curtis Russell• Mark Nelder• Leigh Hobbs• Samir
Patel• Filip
Ralevski• Stephen Moore• Doug Sider• Vaneet
Rakhra• Steven Johnson
• Public Health Agency of Canada• Robbin
Lindsay• Nick Ogden
44