1. Lyme Disease Case Study: Binghamton University Campus
Nasser Sharareh
Advisor: Prof. Sabounchi
Systems Science and Industrial Engineering Department
State University of New York at Binghamton
System Dynamics Colloquium (WPI) - Spring 2016

2. Acknowledgement
Data has been gathered for 3 consecutive years by Professor Garruto and his student, Amanda Roome from Anthropology Department
This project is a cross disciplinary research between SSIE & Anthropology

3. Introduction
About 300,000 Americans are diagnosed with Lyme disease each year [CDC, 2015]
Lyme disease treatment entails a huge cost of $712 million to $1.3 billion per year for the health care system in United States
Treatment
Testing Lyme disease
Patients having return doctor visits for their continuous symptoms of pain and fatigue
Post Treatment Lyme Disease

4. Introduction
System Dynamics (SD) modeling has been used to develop a simulation tool to evaluate significance of different risk factors in replicating historical trend on the number of Lyme disease cases
22 paths were observed at the Binghamton University campus for a 2-year period, from 2013 to 2014, by anthropology Department

5. Data
Path type (Organic like woods - Non-organic like concrete pathways)
Tick density in each path: Dragging cloth through the path nd on the sides
Human behavior: Observing people who were passing each path for 4 days during Fall or Spring
Risk events: each time a human in a given day is observed to do any risky behavior (e.g. sitting on the grass) or clothing (e.g. wearing shorts)
𝑅𝑖𝑠𝑘 𝐸𝑣𝑒𝑛𝑡𝑠 𝑇𝑜𝑡𝑎𝑙 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝐼𝑛𝑑𝑖𝑣𝑖𝑑𝑢𝑎𝑙𝑠 =% 𝑜𝑓 ℎ𝑢𝑚𝑎𝑛 𝑅𝑖𝑠𝑘
They gathered the data for people one week in each year. three days in a week and one day in weekend
They dragged just the sides of concrete pathways. but for organic pathways they dragged all the way and also the sides

6. Data
Susceptible population were estimated by the number of people who were passing each path in each day
𝑆𝑢𝑠𝑐. 𝑃𝑜𝑝. 𝑜𝑓 𝑒𝑎𝑐ℎ 𝑝𝑎𝑡ℎ= 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑖𝑛𝑑𝑖𝑣𝑖𝑑𝑢𝑎𝑙𝑠 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑖𝑛 𝑒𝑎𝑐ℎ 𝑝𝑎𝑡ℎ 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑖𝑚𝑒𝑠 𝑒𝑎𝑐ℎ 𝑝𝑒𝑟𝑠𝑜𝑛 𝑝𝑎𝑠𝑠 𝑎 𝑝𝑎𝑡ℎ

8. New York State LD Cases Growth
According to (Mowbray, Amlôt et al. 2014), the number of cases in UK and Wales has been increasing due to growth in awareness of LD and better diagnosis, but the growth of tick populations and people’s risk behaviors in areas with infected ticks can also lead to an increase in the number of reported cases
This is our hypothesis
And the literature approves it (UK and Wales)
Ref.: Mowbray, F., et al. (2014). "Predictors of protective behavior against ticks in the UK: a mixed methods study." Ticks and tick-borne diseases 5(4):

9. Our Hypothesis Similarly, we hypothesis that:
Recognition have gone up definitely by the medical community, consumers, and public as a result of raising awareness in the past decade
People awareness make LD cases decrease
Medical community recognition make LD cases increase
Tick population have increased due to the abundance of deer and infected rodents

11. Increase of Awareness

12. Are being calibrated From data
we want to have an initial estimation (later we will do MSM), we need to modify it
Mention the risk factors.
Method of Simulated Moments by Hazhir,…jalali
Font should be 13,14 - Arial

13. LD Cases 2012 2013 2014 Broome County LD Cases (NYSDOH) 64 207 152
Broome County Population
198670
198203
197349
Campus Population (Students & Faculty members)
16174
16985
17639
Scaled Down NYSDOH data to Campus
5.21
17.73
13.58
Cumulative Cases
22.94
36.53
we scaled down CDC data to campus because there is too much uncertainty for campus data since people
will go more to the hospital instead of campus health center just because of their perception.
when they have health insurance they will use hospitals rather than health center binghamton, and also hospitals are a walk-in facility and it's very easy for them

14. Initial Calibration Results

15. Public Awareness nsharar1@binghamton.edu It starts from 48% in 2013
Our goal is to have 100% awareness, so we used a goal gap structure.

16. Calibration Result Average Time to Become Aware = 187.06 Days
Initial Awareness =
Average Recovery Time After Developing LD = Days
Average Recovery Time After The Post Treatment Stage = Days
Average Infection Time = 2 Days
Average Time a Person Pass a Path =
Risk of Tick Encounter by Pathway Type - Organic =
Risk of Tick Encounter by Pathway Type - Non-Organic =
Probability of Tick Bites per Person per 1000 m^2 =
Probability of Tick Bites per Person per 1000 m^2 =
Exposure is the HR and Pathway risk
What’s the probability of getting tick bites with this amount of exposure and tick density

17. Extending the Time Horizon
Capture LD Cases growths from 2008 to 2014
Available date: NYSDOH LD Cases and data for
Assumptions:
Kept the human risk and Susceptible population stable over time (for simplification purposes we have not yet considered increase of campus population from 2008 to )
We kept all the values we got for the parameters from last model ()we calibrate later
Parameters to calibrate
Calibrated the 2008 infected ticks density
Calibrated initial awareness of people
Mention the reasons for capturing longer time horizon:
1-we had just data for 2 years, but the LD cases is available for more than 10 years – we wanted to capture the trend of LD in Hudson
Student and faculty population increased 2500, undergrads increased 2000

18. Density Function
Smooth function, not an analytical function

19. Updated Results using LD Incidence

20. Insights
We can’t ignore the risk of getting LD in non-organic pathways (Tadiri, C., et al. (2011) ignored it)
Path Number
LD Cases after 2 Years
Type of Path
Number of Passerby
Pathway Risk P1
3.49
Non-Organic
579 9% P2
18.47
Organic 69
45% P4
1.22 40
P13
1.5 20
P22
3.76
444

21. Insights
Increasing public awareness can’t solve the issue, hence, we should focus on controlling the risky behaviors.
Deer population should be controlled by increasing hunting (Many people dislike it and it’s not good for campus reputation)
it's maybe a aged-related factor that awareness doesn't help (or they feel safe in campus
and they don't know it's risky) also, even if they know, they don't change their behavior.
just having knowledge doesn't force action
according to the survey in campus, students were saying we are controlling, but the actual observation
doesn't show that because they were not wearing long pants and controlling the risky behaviors

22. Future Directions
The seasonal and temperature effects on tick, and hosts population growth
The influence of deer population and small rodents on tick reproduction
Modifying Density and Awareness functions
Developing model for greater areas like Hudson Valley
Policy analysis and preventive strategies

23. Thanks for your time and I appreciate your feedback