Foster CD Conference 2012 - Michigan · NPS and MDNR from visitors and staff at SBDNL Photo: Graham...
Transcript of Foster CD Conference 2012 - Michigan · NPS and MDNR from visitors and staff at SBDNL Photo: Graham...
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Erik FosterMedical EntomologistMichigan Department of Community Health
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Outline
America’s Most Beautiful PlaceMotivation for study Lyme disease Epidemiology
in Michigan A note on human case
investigation Study results
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Well Deserved Recognition
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
SBDNL Park Statistics
Est. 1970
Annual Visits ‐ 1,143,857
Employees ‐ 46 permanent, 84 seasonal
Volunteer Hours ‐ 29,595 from 850 volunteers
Area ‐ 71,199 acres
Lake Michigan Shoreline ‐ 65 miles (35 miles on the mainland)
Campgrounds ‐ 9 (357 sites)
Miles of trails ‐ 105
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Unwanted Visitors
MDCH and MSU have been conducting collaborative surveillance for blacklegged ticks and Lyme disease since the 1980’s
In the Lower Peninsula the Lake Michigan shoreline has the highest blacklegged tick populations, but historic tick surveys have so‐far shown little risk at southern sites at SBDNL
Since 2010 reports of blacklegged tick encounters have increased to NPS and MDNR from visitors and staff at SBDNL Photo: Graham Hickling
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Motivation for Study
Reported Lyme disease cases in Michigan (2010‐2011) have been linked to potential exposure at SBDNL and specifically North Manitou Island
SBDNL accommodates ~1.2 million visitors per year during the peak of tick season
Michigan DCH, MSU, and NPS discussed need/plan to evaluate risk on Manitou Islands and SBD mainland
Documenting the presence and distribution of blacklegged ticks in the park will assist the NPS in worker protections and directing public education re: tick‐borne disease prevention
Photo: Jen Sidge
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Project Approach: What and Where to Sample?
Objectives1. Determine if Ixodes scapularis is
present, and at what concentration at North and/or South Manitou Islands
2. Determine if B. burgdorferi is present in ticks and/or wildlife at four sites within the SBDNL
3. Compare findings with a positive control site within a Lyme disease endemic region of Michigan’s Lower Peninsula
4. Provide recommendations to the NPS related to potential Lyme disease risk based upon survey results at SBDNL
Four experimental sitesMainland SBDNL: Southern and Northern siteManitou Islands: South and North islands
Control siteVan Buren State Park Photos: Jean Tsao
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
SBDNL Sites
Dragging: along trails and transects: ~ 3000 m dragging per site/visit (June‐October, 2011)
Rodent trapping: Two nights with 150 – 216 traps per night
(June‐September, 2011)
Hunter killed deer: Annual deer hunt October 29 –November 5, 2011
North Manitou Island
South Manitou Island
DH Day Campground
Platte River Campground
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SouthSouth NorthNorth
Motorized vehicles allowed
Organized campgrounds
Village Area/Lighthouse
Daytrips Common
Higher visitation
No motorized vehicles
“Wilderness” camping
No daytrips
Lower visitation
Potentially higher exposure to wooded environments
Island Comparison – What we know going in
WHAT IS LYME DISEASE?
HOW PREVALENT IS IT IN THE U.S. AND MICHIGAN?
WHAT ARE THE RISK AREAS?
First Off…..
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Tick-Borne Illness in Michigan
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
What is Lyme Disease?
Tick‐borne disease transmitted by the Blacklegged tick, Ixodes scapularis
Bacterial, spirochete, Borellia burgdorferi
Transmission from tick to host takes 24‐48 hours
No person‐to‐person spread
Range of potential symptoms and difficulties interpreting laboratory results makes reported Lyme difficult to characterize for public health surveillance purposes
phil.cdc.gov
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Clinical Findings, 1992-2004
Lyme disease is a nationally notifiabledisease. The Centers for Disease Control and Prevention collect and analyze data from all states.
The graph at right illustrates percent of clinical findings among 119, 965 patients for whom at least one symptom was reported.
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Lyme disease has emerged over time....
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
1999 2009
....and over space
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Current tick distribution
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How can it be that our most beautiful place is plagued by ticks?Prior to 2002, No local
populations of blacklegged ticks had been identified in the Lower Peninsula.
Over the past decade, extensive field surveys have documented a northward progression of tick invasion along Michigan’s western shoreline.
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
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Tick Phenology in Southern Michigan
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Infection Analysis by Stage at a Southern MI Study Site: 2002‐2004
Total No. Tested Number Infected Infection Rate
40%
34%
15%
Historic Southern Michigan Infection Rates
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Michigan Human Cases 2006-2011
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Case Onsets: 2011
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Western Lower MI Exposures
UP MI Exposures
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Michigan regional trends: 2000-2011
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Linear (Other MI Exposure) Linear (Out of State Exposure)Out of State ExposureUpper Peninsula Exposure
Other Michigan ExposureWestern Lower MI Exposure
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(Left) Lyme disease risk based on known populations of infected tick vectors. (Right) Incidence of locally acquired human Lyme disease cases, 2011.
EPI SNAPSHOT 2011
Incidence of locally acquired Lyme disease
Full State:
1.06 cases/100,000 pop.
Western Upper Peninsula:
17.49 cases/100,000 pop.
[*99.98 cases/100,000 pop. In Menominee Co.]
Western Lower Peninsula:
1.26 cases/100,000 pop.
Counties outside of western UP/LP regions:
0.09 cases/100,000 pop.
Lyme disease risk and human case incidence in Michigan, 2011
BROAD SUMMARY
INTERESTING DIFFERENCES
TANTALIZING SCIENCE
Interesting Findings at Sleeping Bear…..
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Preliminary Summary
Ixodes scapularis ticks were found at all SBD sites surveyed
Borrelia burgdorferi was isolated from ticks or animals at all sites EXCEPT South Manitou Island
Mainland site tick densities and infection rates are indicative of initial invasion/ongoing colonization
High adult questing density on NMI during October hunt
Adult tick density and infection rate at North Manitou Island is comparable to an established, southern Michigan control site
Tick Contact in the Environment
Ticks sampled by dragging a 1‐meter x 1‐meter corduroy cloth through forest understory
When compared with control site, NMI has highest adult and nymph stage tick density; densities as S. Platte have increased. Little activity at DH Day and SMI.
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Results of >44,000-m2 drag-sampling (>27 miles)
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
“Entomological Risk Index”
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“The amount of chipmunks and breeding habitat for the nymphs (young ticks) is a perfect cocktail for the spread of Lyme disease at a alarming rate....”
Eastern chipmunks are highly competent hosts for B. burgdorferi and previous studies point to high parasitism by nymphalblacklegged ticks.
North and South Manitou Islands have high populations of this important host species compared to a southern Michigan control site. 0
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Unique Captures
Eastern Chipmunk Captures ‐ SBDNL Tick Survey Data 2011
VBSP (Control) NMI SMI DH Day S. Platte
Photo: Jean Tsao
Results of >3,400 trap nights
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Ticks on wildlife hosts
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
B. Burgdorferi infected animals
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Proportion of tissue biopsies positive
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Hunter Collected Ticks
In October, 2011 hunters bound for the NMI annual hunt were recruited to collect ticks from themselves and harvested deer.
Hunters were asked to participate in survey and briefed about ticks and Lyme disease risk while en‐route to the island
40 collection kits were distributed including forceps, collection tube, instructions, data sheet, pen and gloves
Hunters were given gift card to participate
Photo: Jen Sidge
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Hunter collected ticks results
40 collection kits distributed 22 (55%) kits returned at the end of the hunt
196 ticks collected (all adult I. scapularis)
Collection range was: 1 to 24 ticks with a mean of 9.38 ticks/hunter
Probable tick collection locations were marked on a map by hunters
48% of ticks collected showed evidence of B. burgdorferi infection by PCR
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North ManitouNorth Manitou South ManitouSouth Manitou
High density small mammal hosts
Mixed deciduous, sandy soils
White‐tailed deer population
Other medium sized mammals (coyote)
HIGH density ticksHIGH B. burgdorferi rate
High density small mammal hosts
Mixed deciduous, sandy soils
NO White‐tailed deer population
Few to no other medium sized mammals
LOW density ticksNO B. burgdorferi
Compare North vs. South Island
How did I. scapularis ticks arrive on the islands?
Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Conclusions
Lyme disease is the most commonly reported vector‐borne disease in Michigan
Tick populations and Lyme disease risk continue to expand geographically in Michigan, now encompassing the entire western shoreline of the Lower Peninsula
More study is warranted to estimate the entomolgic risk index (density B. burgdorferi infected nymphs/1000m2) at SBDNL as well as: What factors contribute to differences in tick density and infection rate
(NMI vs. SMI)?
Do birds play a role in introducing ticks to the islands?
Are the tick introduction rates similar between the islands?
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Kellogg Hotel and Conference CenterMay 16, 2012 - East Lansing, MI
Michigan Classification Flowchartfound at www.michigan.gov/cdinfo