The Immunological
Basis for Disease
Dilution
Sheena Wheeler
Dr. Anna Jolles
RELEVANCE
•Many human diseases are transmitted
from non-human animals (Zoonotic
diseases)
•Some species are better at transmitting
diseases than others
•Biodiversity is important to ecosystem
services
BACKGROUND
Disease Dilution: Empirical Findings
high biodiversity = reduced risk of disease
low biodiversity = increased risk of disease
Sin Nombre Virus in Deer Mice (Laurie J. Dizney)
BACKGROUND
BIODIVERSITY =
=
DISEASE
Why is the deer mouse good at transmitting
disease?
HYPOTHESIS
We hypothesize that short-lived species invest
less in certain aspects of their immune system,
which may make them better at transmitting
diseases.
Ex:
VS.
MY OBJECTIVE
To examine the immune differences between
short-lived and long-lived rodent species
METHODS: FIELD
1. Trap different rodent species
throughout Oregon (Sherman
and Tomahawk traps)
2. Collect blood, feces, and
ectoparasites from each
rodent
3. Ear tag, measure, weigh and
release
TRAPPING LOCATIONS
1. Local
2. Rogue RiverSiskiyou
National Forest
3. Willamette
National Forest
4. Steens
Mountain
Eastern OR
MY OBJECTIVE
To examine the immune differences between
short-lived and long-lived rodent species
1.Determine the differences in white blood cell
composition between rodent species.
BACKGROUND
White blood cells (WBC): travel in
bloodstream to infected areas and destroy
responsible bacteria
WBC
BACTERIA
Complete Blood Count:
•Determine numbers and types of white
blood cells (WBC) in an animal
Good general way to see how the immune
system of an animal functions
METHODS: LAB
1. Perform complete blood counts (CBC) on each
rodent:
A) White blood cell counts
B) Cell differentiation
Lymphocyte
Neutrophil
Band
Monocyte
Eosinophil
Basophil
MY OBJECTIVE
Examine the immune differences between shortlived and long-lived rodent species
1.Determine the differences in blood cell
composition between rodent species.
2.Evaluate the health of different rodent
species via fecal parasite analysis.
METHODS: LAB
1. Fecal Float to examine the types of parasite eggs
2. Fecal McMasters to count the different parasite eggs
within the feces
PICTURES
PRELIMINARY RESULTS
1. Complete Blood Counts
Table 1: Average and standard deviation of total white blood
cells/μl for six species of rodents.
Species
California Ground
Squirrel
Sample Size
Average WBC/μl St. Dev. WBC
10
10234.57
Chipmunk
Dusky Footed
Woodrat
3
8666.67
9
8812.5
2863.89
Norway Rat
8
3581.11
3821.13
Black Rat
2
9527.78
2710.58
79
3488.48
2360.07
Deer Mouse
6270.63
PRELIMINARY RESULTS
2. Fecal Analysis
Table 2: Percent of species with fecal parasites and percent of each
type of parasite in each species.
Species
Fecal
Parasites
Sample Size
Coccidia
Capillaria Other
California
Ground Squirrel
Chipmunk
10
3
80.00%
100%
80.00%
100%
10.00% 70.00%
0%
0%
Dusky Footed
Woodrat
Norway Rat
Deer Mouse
9
8
79
100.00%
50.00%
25.53%
100.00%
67.00%
21.28%
75.00% 0.00%
33.00% 0.00%
0.00% 0.02%
Pinyon Mouse
4
100.00%
33.00%
0.00% 67.00%
WHAT’S NEXT?
•Continue data collection of rodents around
Oregon
•Trap larger/longer lived rodents (beaver, nutria)
•Analyze data
ACKNOWLEDGEMENTS
Howard Hughes Medical Institute (HHMI)
Undergraduate Research, Innovation,
Scholarship and Creativity(URISC)
Dr. Anna Jolles
Dr. Rhea Hanselmann
Dr. Kevin Ahern