Flux of Ixodes scapularis on Host Peromyscus leucopus, and the Establishment of Lyme Disease Borreli

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Flux of Ixodes scapularis on Host Peromyscus
leucopus, and the Establishment of Lyme Disease
(Borrelia burgdorferi) in a Central Illinois
Forest

• Ray Eckensten

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What Is Lyme Disease?

• It is caused by a bacteria, Borrelia
  burgdorferi,which attacks the human nervous
  system
• Lyme disease is a vector-borne disease, carried
  by deer ticks (Ixodes scapularis)

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Borrelia burgdorferi
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What Is a Vector Borne Disease?

• A disease that is not transmitted from human to
  human, but by an animal
• The animal that transmits the disease is referred
  to as the vector
• Often there is a population of animals that
  sustains the bacterial source of the disease.
  That population is called the reservoir

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Lymes Villainous Vector I. scapularis
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Life Cycle of a Vector I. scapularis
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Meet Our Reservoir Peromyscus leucopus
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B. Burgdorferi Transmission Cycle
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Those Darn Deer

• White-tailed deer had been over hunted in parts
  of the Midwest in the late 19th century
• To repopulate them in newly established state
  parks, deer from Pennsylvania were imported
  during the and 30s and 40s
• Lyme infested I. scapularis probably tagged
  along

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I. Scapularis distribution, 1996
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Lyme Disease Distribution
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The Epidemiology of Lyme Disease

• Lyme is a disease that is still on the move
• By studying I. scapularis habitat, deer movement
  patterns, and the distribution of Lyme disease,
  we can predict where Lyme will appear next, and
  what areas are most at risk

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Predicting Lyme the Risk Map

• This map indicates habitat suitability for I.
  scapularis, as well as areas where the tick has
  already established itself
• Based on deer movement data, it is expected that
  the ticks will be moved along riparian corridors
  by migrating deer populations

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Rays Study

• Intended to improve the risk map study by taking
  a closer look at Lymes vector-reservoir
  relationship.
• What is the flux of ticks on and off of mice?
• How does this affect how quickly Lyme can become
  endemic to an area that already has an
  established I. scapularis population?
• The risk map tells us about an areas risk of I.
  scapularis appearance, but how well suited is it
  to predicting Borrelia burgdorferi appearance?

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Rays Study Site

• The site selected was an area that had been
  recently infested with ticks (within the last 4
  years), but as yet had no evidence of B.
  burgdorferi
• A county park near the Illinois river in the
  north-central region of the state
• Forested White oak, pin oak and red maple
  dominant with abundant leaf litter

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Procedures

• Over a period of three nights, three grids of 50
  traps each were set.
• Traps were checked and re-baited every morning
  and evening.

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Sherman Live Traps
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Procedures Continued

• Captured small mammals were put into a narcosis
  chamber containing halothane.
• Once unconscious all I. scapularis were removed
  with forceps.
• Mammals were then released at their site of
  capture.

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Preliminary Conclusions

• The preliminary data indicate a high flux of
  ticks on the mice in a 24 hour period, gt4 ticks
  per night
• This creates an ideal situation for a quick
  spread of Lyme in the site when it is introduced

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Current State of The Project

• The data from this project is now being entered
  into ArcGIS and SPSS (a spatial statistics
  program) in hopes of creating a model of the
  spread of Lyme through the site.

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Implications of Research

• Ideally, this study will give some insight into
  how quickly Lyme disease can be expected to go
  from introduction to an endemic state in an
  Illinois riparian forest.
• It is my hope that the data and results of my
  project will be used to help create statewide B.
  burgdorferi models and risk maps.