Outline America's Most Beautiful Place Motivation for Study Lyme Disease

5/7/2012

Erik Foster Medical Entomologist Michigan Department of Community Health

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

Outline

 America’s Most Beautiful Place  Motivation for study  Lyme disease Epidemiology in Michigan  A note on human case investigation  Study results

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Well Deserved Recognition

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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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 Center May 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 Photo: Jen Sidge prevention Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Project Approach: What and Where to Sample?

Objectives 1. 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 sites Mainland SBDNL: Southern and Northern site Manitou Islands: South and North islands Control site

Van Buren State Park Photos: Jean Tsao

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

SBDNL Sites

Dragging: along trails and North Manitou transects: ~ 3000 m dragging Island per site/visit (June‐October, South Manitou 2011) Island Rodent trapping: Two nights DH Day Campground with 150 – 216 traps per night (June‐September, 2011)

Hunter killed deer: Annual Platte River deer hunt October 29 – Campground November 5, 2011

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Island Comparison – What we know going in

SouthSouth North

Motorized vehicles No motorized vehicles allowed “Wilderness” camping Organized campgrounds No daytrips Village Area/Lighthouse Lower visitation Daytrips Common Potentially higher Higher visitation exposure to wooded environments

First Off…..

WHAT IS LYME DISEASE? HOW PREVALENT IS IT IN THE U.S. AND MICHIGAN? WHAT ARE THE RISK AREAS?

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Tick-Borne Illness in Michigan

Kellogg Hotel and Conference Center May 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 phil.cdc.gov . 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

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Clinical Findings, 1992-2004

Lyme disease is a nationally notifiable disease. 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.

Lyme disease has emerged over time....

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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....and over space

1999 2009

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

Current tick distribution

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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How can it be that our most

Prior to 2002, No local beautiful place is plagued by ticks? 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.

Tick Phenology in Southern Michigan

Larvae Nymphs Adults

0.3 activity

0.2

0.1 Relative

0 123456789101112 Month

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Historic Southern Michigan Infection Rates

Infection Analysis by Stage at a Southern MI Study Site: 2002‐2004 700 45 40% 600 40 34% 35 500 Infection 30 400 25 Number

Rate 300 20

15% 15 (%) 200 Absolute 10 100 5 0 0 total female male nymph Life Stage Total No. Tested Number Infected Infection Rate

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Michigan Human Cases 2006-2011

120 Unknown Exposure 106 103 Out-of State Exposure 95 100 92 In-State Exposure

58 60 52 # Cases

0 2006 2007 2008 2009 2010 2011

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Case Onsets: 2011

Other Exposures

10 Western Lower MI Exposures UP MI Exposures

6 # Cases

0 5 1318192022232425262728293031323334353638394041424445 May June July August MMWR Week

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Michigan regional trends: 2000-2011

45 40 35 30 25 20 15

No. Cases No. 10 5 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year WesternLinear (SW Lower MI Exposure) MI Exposure LinearUpper (UP Peninsula MI Exposure) Exposure LinearOther (OtherMichigan MI Exposure) Exposure LinearOut of (Out State of ExposureState Exposure)

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Lyme disease risk and human case EPI SNAPSHOT 2011 incidence in Michigan, 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: (Left) Lyme disease risk based on known populations 0.09 cases/100,000 pop. of infected tick vectors. (Right) Incidence of locally acquired human Lyme disease cases, 2011.

Interesting Findings at Sleeping Bear…..

BROAD SUMMARY INTERESTING DIFFERENCES TANTALIZING SCIENCE

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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

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

Results of >44,000-m2 drag-sampling (>27 miles)

60 VBSP (Control) NMI 50 SMI 40 DHD SP 30 Adult Ticks

Tick Contact in Adults/1000m2 I.scap Density 0 the Environment Early-Mid June Mid-July Mid-September Mid-Late October Ticks sampled by dragging 8 a 1‐meter x 1‐meter VBSP (Control) 7 corduroy cloth through NMI forest understory 6 SMI 5 DHD Nymph Stage SP When compared with 4 Ticks control site, NMI has 3 highest adult and nymph 2 stage tick density; 1 Density I.scap Nymphs/1000m2 I.scap Density densities as S. Platte have 0 Early-Mid June Mid-July Mid-September Mid-Late increased. Little activity October at DH Day and SMI.

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“Entomological Risk Index”

Adult Tick Entomological Risk Index Nymphal Tick Entomological Risk Index 16 0.6 14 0.5 12 0.4 10

8 0.3 ticks/1000m2

6 0.2 4 Infected

# 0.1 2

0 0 Early‐Mid June Mid‐July Mid‐September Mid‐Late Early‐Mid June Mid‐July Mid‐September Mid‐Late October October VBSP NMI SMI DHD SP VBSP NMI SMI DHD SP

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

Results of >3,400 trap nights

Eastern Chipmunk Captures ‐ SBDNL Tick Survey Data 2011 Eastern chipmunks are 60 highly competent hosts for B. burgdorferi and previous 50 studies point to high parasitism by nymphal 40 blacklegged ticks. Captures 30 North and South Manitou

Islands have high Unique 20 populations of this important host species 10 compared to a southern Michigan control site. 0 Early‐Mid June Mid‐July Mid‐September

VBSP (Control) NMI SMI DH Day S. Platte

“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....” Photo: Jean Tsao

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Ticks on wildlife hosts

0.70 1.20 VB (Control) 0.60

LL NMI 1.00

0.50 SMI I.scap

0.80 I.scap

w DHD 0.40 w SBD 0.60 EACH

0.30 EACH 0.40 0.20 Proportion

0.10 Proportion 0.20

0.00 0.00 Early‐Mid June Mid‐July Mid‐September 0.80 0.40 Early‐Mid June Mid‐July Mid‐September LL 0.35

0.70 NN scap 0.60 0.30 I.

I.scap w

0.50 w 0.25

0.40 0.20 WFMO

WFMO of 0.30 0.15 0.20 0.10 0.10 0.05 Proportion Proportion 0.00 0.00 Early‐Mid June Mid‐July Mid‐September Early‐Mid June Mid‐July Mid‐September

B. Burgdorferi infected animals

0.6 VB (Control) NMI 0.5 SMI DHD

positive SBD

0.4 biopsies

0.3 tissue

0.2

0.1 Proportion

0 Early‐Mid June Mid‐July Mid‐September

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Hunter  Hunters were asked Collected Ticks 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 Photo: Jen Sidge  Hunters were given In October, 2011 hunters gift card to bound for the NMI annual hunt were recruited to collect participate ticks from themselves and harvested deer.

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

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Compare North vs. South Island

North Manitou South Manitou

 High density small mammal  High density small mammal hosts hosts  Mixed deciduous, sandy  Mixed deciduous, sandy soils soils  White‐tailed deer  NO White‐tailed deer population population  Other medium sized  Few to no other medium mammals (coyote) sized mammals  HIGH density ticks  LOW density ticks  HIGH B. burgdorferi rate  NO B. burgdorferi

How did I. scapularis ticks arrive on the islands?

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?

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI

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Michigan Classification Flowchart found at www.michigan.gov/cdinfo

Kellogg Hotel and Conference Center May 16, 2012 - East Lansing, MI