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GIS for Public Health
Analysis of the geographical relationship between environments and
diseases has long been a cornerstone of public health. The classic,
textbook example is John Snow's study of cholera transmission in
London, which has recently been the subject of scholarly re-
evaluation. Public health is now a rapidly expanding field for GIS.
It is the focus of the ESRI Health GIS Conference, which will take
place October 23-26, in Denver, Colorado, and it was the subject of
about 40 technical workshops at the recent ESRI user conference.
At one of the workshops, Megan Blewett, a brilliant high school
student who spent much of the summer doing research at the Broad
Institute of MIT and Harvard, gave a flawless presentation of a
study she had recently completed. Her paper (this link is to a
draft) examined whether Multiple Sclerosis (MS)-the most common
primary neurological disorder of young adults-belongs in the same
category as Lyme Disease, West Nile Virus, and other zoonotic
diseases, which are caused by infectious agents that can be
transmitted between animals and humans.
[Photos omitted on LymeInfo - go to URL at top of page to view
photo captioned below.]
Megan Blewett working in her lab
Blewett first began to examine the relationship between MS and Lyme
after being struck by the similarity in distribution maps of the two
diseases. Epidemiological and biochemical similarities suggest a
common bacterial basis for MS and Lyme. If there is a zoonotic
influence in MS, Blewett reasoned, geostatistical analysis
(inferential statistical techniques combined with data visualization
and cartographics) should show that MS has the same geographic
distribution as similar zoonotic diseases-and that the latter are
good predictors of the former. As a control variable, Blewett used
accident/injury, because this condition should be unrelated to a
bacterial distribution.
Blewett obtained mortality counts from the Centers for Disease
Control and Prevention (CDC), population data from the 1990 Census,
and population elevation data from the MIT Geoserver and the U.S.
Census Gazetteer. She constructed a database of the elevation of
each county seat, which she then gave to ESRI for use by other
researchers.
>From the start, Blewett had to contend with, in her words, "the
current lack of standardization in health geographics data." Because
Lyme is a reportable illness, she had assumed that she could readily
find a standardized Lyme incidence dataset online. Instead, she had
to contact (and follow up with) every single state epidemiologist.
She entered the data into an Excel spreadsheet for each of the 3,141
counties in the United States for each of the years from 1992
through 1998-in the process creating the most comprehensive dataset
available on Lyme incidence at the county level. "This process took
several months," she told me, "though I am currently making this
dataset available to other researchers."
To compare the distributions of different diseases, Blewett had to
compile a database of their incidence and of their associated
environmental variables. She began with a search for an
authoritative source of incidence and prevalence data for Lyme, MS,
breast cancer, ALS, and accidents/injuries. Death certificates are
filed at the state level and coded in a standard way across all
states. The information is then collected from the states by the
National Center for Health Statistics, which publishes it along with
other vital statistics. Blewett determined the appropriate code for
each of the five diseases of interest, then used these codes in
DataFerrett to extract the state of residence for those who died of
those diseases in the United States in 1998.
To calculate the incidence variables for each state, she added to
this data the population from the 1990 Census and the 1998 deaths
from DataFerrett. She used the same method to obtain data at the
county level. To this state and county data, Blewett added the
number of new Lyme cases reported each year from 1992-1998, the
centroid latitude, the centroid longitude, and the population
elevation, then averaged the centroid latitude and longitude over
all counties in a state to calculate the state value. She repeated
this process to calculate each state's population elevation.
The results of Blewett's statistical analyses support geographically
the proposed connection between MS, Lyme, and related diseases,
while the geographic distribution of the control variable is very
different. Her correlations and regression analysis also show a
clear geographic co-occurrence of MS and Lyme but no such
relationship with the control variable. This suggests a common cause
for MS and Lyme. The strong association of MS with motor neuron
disease (ALS) and the weaker, but significant, association with
breast cancer, also suggest a possible common environmental
mechanism for these diseases.
In her paper, Blewett also explains the results of her statistical
analyses using biochemical principles. This summer she studied the
chemical structures of compounds that bind uniquely with Neuregulin,
a protein that appears to play a role in many of the diseases that
her maps had showed to be geographically correlated. "I find it
interesting," she told me, "that the epidemiological commonalities I
found hold up on the biochemical level as well. This seems to give
credence to the hypothesis that a common agent may be at work in MS
and related diseases."
Blewett is careful to point out several possible confounding factors
and spurious correlations. People diagnosed with chronic illnesses
often move to Florida or California, because of the weather in those
states, or to East Coast states with better healthcare. States with
higher rates of diagnosis sometimes display lower death rates
because, with experience, doctors in those areas often are more
familiar with treating the disease. To protect the privacy of
individuals, federal statistics lump together data for counties with
fewer than 100,000 residents; this excludes mostly rural counties,
which have a higher incidence of Lyme transmitted by ticks in wooded
areas. Finally, MS and Lyme are commonly misdiagnosed and people's
state/county of residence may not be a good indicator of where they
were exposed to a disease.
Blewett found ArcGIS 9.1, without any extensions, sufficient for
mapping the distributions of diseases. She used Excel to create her
datasets and SPSS to calculate the descriptive and inferential
statistics and to run the correlations and the multiple regressions.
She saved the SPSS file as a Dbase IV file, then opened it and saved
it in ArcGIS to use in her cartographic analyses.
"Overall," she told me, "I have been extremely satisfied with the
ArcGIS software. This technology has given me insight I would not
have gained using more conventional biochemical / statistical
techniques. In the future, I want to explore the ArcGIS statistical
package and other ArcGIS extensions. Operating individually also
means that cost is an issue; ESRI was very generous in supplying me
with the tools I needed. I especially enjoyed presenting at the ESRI
user conference."
What are Blewett's plans for future research? "One of my focuses
now," she says, "is collecting more datasets. I hope to compare MS
distribution to bird migratory patterns, tick density, and
population density, among other factors. I am still searching for a
nationwide comprehensive tick distribution dataset."
Will GIS remain one of her key tools? "GIS holds the potential to
answer questions few other approaches can. I hope to continue to use
GIS to investigate the epidemiological overlap between MS and Lyme.
Since the cause of Lyme has already been identified as a spirochetal
bacterium, looking at commonalities could eventually reveal the
cause of MS as well. Future steps include using standard deviational
ellipses to both compare disease distributions and to investigate
the spread / saturation of the diseases over time. I often worry
that medical research today is not sufficiently goal-oriented.
Scientific fields of study are becoming increasingly narrow and
complex. GIS allows us to see the big picture and I hope to use it
to guide any future biochemical investigation of these disorders."
The next presenter in the workshop, who is just completing her PhD,
probably expressed the feelings of most of the people in the
audience: when she was Blewett's age, she said, her biggest
technical challenge was learning to drive a stick shift!
________________________________________
===
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Posted by timaca (Member # 6911) on :
There is a DVD for sale at www.unh-lyme.org that discusses Lyme and MS. It is $15. I ordered one.
Timaca
Posted by pq (Member # 6886) on :
pathology indices shared by illneses commonly misdiagnosed for one another.
http://actionlyme.org/Pathology_indices.htm
see also: http://actionlyme.org/BIOMARKERS.doc
video of klempner's secret haplotype for multiple sclerosis: http://actionlyme.org/BIOMARKERS.doc
"Mark Klempner found the other Multiple Sclerosis haplotype in Lyme
patients, and the US recruited Roland Martin from Germany to work at
NINDS because Martin found the first MS haplotype in Borreliosis
patients. That's sort of still a secret but you can get the full text
article and read what he did. Klempner-0602.wmv = Klempner speaking
about his Multiple Sclerosis Haplotype finding, which is still a dot
guv secret. "
from kathleen dickson on sci.med.diseases.lyme
[ 02. September 2006, 02:06 AM: Message edited by: pq ]
Posted by pq (Member # 6886) on :
further study on the MS-Lyme "link":
"Mark Klempner found the other Multiple Sclerosis haplotype in Lyme
patients, and the US recruited Roland Martin from Germany to work at
NINDS because Martin found the first MS haplotype in Borreliosis
patients. That's sort of still a secret but you can get the full text
article and read what he did. Klempner-0602.wmv = Klempner speaking
about his Multiple Sclerosis Haplotype finding, which is still a dot
guv secret."
" The secret Klempner haplotype, HLA-DQB1*0602 is related to
narcolepsy, MS, Lupus, and worse cases of HIV and tuberculosis. We
don't know what roles TLR polymorphism play... "
from kathleen dickson on sci.med.diseases.lyme:
http://tinyurl.com/l76eb
[ 02. September 2006, 09:14 PM: Message edited by: pq ]
Posted by bettyg (Member # 6147) on :
Jim, is this the post that I broke up making it easier reading of Megan Blewett's thesis? If not, there is an easier one to read.
Speaking of Megan, she emailed me this week. A local senior also wrote a LYME PAPER that was recognized nationally and won awards.
I tried calling this HS girls home but she was gone. Wanted to read it IF it were on my neuro lyme level, but brother said it was very technical like Megan's.
I sent Megan a note about this woman's lyme paper. She'd like to get together with her and discuss what each of them have accomplishd.
Can you imagine these 2 BRILLIANT MINDS discovering LYME MIRACLES on our behalf? I CAN!!
Unfortunately, I threw away the name of the gal I called; waiting to see if Megan wants me to pursue this by calling the HS to see if they would give me her name or not.
Daystar/MARGIE, she talked about coming ONLINE AGAIN in near future!! Hope so.
Bettyg
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Posted by bettyg (Member # 6147) on :
Hi PQ,
Can you use a tinyurl for the really LONG link address? It caused this to go SUPER wide. Thanks so much. Bettyg
Posted by Lymetoo (Member # 743) on :
Hope pq comes back!!
That's pretty awesome data, JB!! Smart girl!
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Posted by pq (Member # 6886) on :
Betty and Tutu: Done. sorry about that.
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