Acknowledging the limitations in Lyme disease distribution maps, and proposing a new method to determine Lyme risk in Colorado.

1. HAVE TICKS
FOUND A HOME
ON THE RANGE?
The correlation between Lyme
disease carrying ticks and
precipitation in Colorado
By Kate Mericle

2. LYME DISEASE
Symptoms Treatment
 Rash
 Joint swelling
 Heart palpitations
 Shooting pain
 Short-term memory loss
 Inflammation of central
nervous system
 Facial Palsy
 CDC recommends 2-3 weeks
of antibiotics
 “Lyme-Literate” MDs treat with
long-term (two years)
antibiotics, mixed success
 Certain species of ticks
 Early Summer
 Possibly congenital
 Possibly sexual
Transmission

3. PROBLEM STATEMENT
 Treatment is most effective if caught early, but it can take years to
get diagnosed, partly due to inaccurate distribution models.
 “A (Colorado) Lyme doc put together my symptoms after
Children’s hospital refused to believe I had Lyme disease even
though I had a positive test.”
 “Was ignored in Oregon. Actually told it didn’t exist there.”
 “Doctors recultant to test because they believe it’s rare in
Arkansas.”

4. Currently Recognized
Distribution Pattern
 According to the CDC…
 Based off county of
residence, not location of
tick bite
 Under-reported in endemic
areas
 Over-reported in non-
endemic areas. I am
challenging this.

5. Non-Endemic Areas
 CDC’s theory: Lyme is
misdiagnosed or the
patient traveled to the
Northeast
 But….
 Doctors aren’t
looking for Lyme
 Don’t report for fear
of litigation

6. NATIONALLY REPORTED CASES IN
COLORADO
 Seven cases
reported between
2008-2010
 CDC “confirmed” 3
cases
 County of residence,
not necessarily
infection

7. LIMITATIONS OF PAST
DISTRIBUTION MODELS
 Models like this one are
asking…
 Can they COMPLETE the life
cycle?
 Variables
 Averages by county
 What about micro-climates?
 What about snowmelt?
Source: Brownstein, Holford, and Fish,
2013

8. SURVEY
Results
 Over 250 total responses
 70 people infected in the West
 Five in Colorado
 Clustered where May is the
wettest month of the year
 Two in Fort Collins
 One in Poudre Canyon
 One in Firestone
 One in Keystone
Source: Colorado Climate Center

9. Precipitation comparison 1998
 Location: Poudre Canyon
 Confidence level 80%
 Could not locate historical
precipitation data

10. Precipitation comparison 2003
 Location: Keystone
 Confidence level 100%
 STORY: “We went to a
festival in Keystone,
and I think I got it from
petting the horses,
which they probably
shipped in from out of
state. They were
Budweiser horses…
Clydesdales.

11. Precipitation comparison 2006
 Location: Fort Collins
 Confidence level 50%
 STORY: “Misdiagnosed
for five years by multiple
doctors. No one ran a
Lyme test for five years.”

12. Precipitation comparison 2013
 Location: Firestone
 Confidence level 100%
 STORY: “clearing off
brush and tall grass for a
garden”

13. Precipitation comparison 2014
 Location: Fort Collins
 Confidence level 100%
 STORY: “I was definitely
bit in the city limits of Fort
Collins. I hadn’t been
anywhere else.”

14. POTENTIAL CHANGES DUE
TO CLIMATE CHANGE
 Increasing temperature = increase humidity. by default
 Inconclusive precipitation predications
 Current conditions are highly variable
 Streams
 Peak melt will be earlier, increasing spring flow, decreasing late summer flow
 Projections Range from -15% to +29%
 Northeast CO more likely than the rest of the state to get wetter
 Southwest CO more likely to get drier

15. RARE –BUT POSSIBLE
 Nymphs can transfer hosts if not yet embedded upon arrival to
CO.
 Larvae can change into a nymph on especially wet years.
 Wet years may become more frequent in Northeastern CO
 It only takes one bite.