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Collection Techniques and Host Specificity of Larval Trematodes
from Aquatic Snails in Tennessee’s Powell River
T. Goldberg, C. Faulkner, L. Brandt
College of Math and Science, Lincoln Memorial University, Harrogate, TN 37752
Introduction/Background Results
Methods
Discussion/Future Directions
Acknowledgements
An estimated 750 million people are at risk of
infections from food-borne trematodes,
including liver flukes, lung flukes, and
intestinal flukes (Keiser & Utzinger, 2009). All
trematodes utilize aquatic snails as their first
intermediate host and an invertebrate or lower
vertebrate, such as a fish, as the second
intermediate host. There is existing research
about general characteristics and the lifecycles
of cercariae; research about collection
techniques and if there is any snail host
specificity in Tennessee’s Powell River does not
exist. The purpose of this study was to develop
effective collection techniques and to determine
if there is any specificity in snail hosts.
Snails were collected from the Powell river and
sorted into aquariums based on genus,129
Leptoxis and 101 Pleurocera. Snails were
maintained in darkness for 48 hours prior to
being placed in 1000 ml beakers. 200 ml DI
water was added to each beaker and then they
were exposed to direct lighting from a daylight
CFL lightbulb. The water from the beakers was
collected at the 2 and 4 hour marks. Water
from the beakers was placed in petri dishes and
examined under a dissecting microscope.
Cercariae were then transferred onto slides
and viewed at 100X.
Keiser, J., & Utzinger, J. (2009). Food-borne
trematodiases. Clinical microbiology
reviews, 22(3), 466-83.
Only one group of morphologically similar
cercariae has been recovered thus far so we can
only speculate that there is not any host
specificity. The initial collection techniques
have been modified and are now successful at
inducing shedding.
Induced shedding will be continued to
determine if there are any other groups of
cercariae present in the snails. Continued
research will also focus on collecting
measurements of the cercariae to classify the
characteristics of specimens and confidently
identify the group. The only successful staining
we have achieved is simple contrast staining
with safranin. Methods for effectively staining
individual structures will be developed to aid in
identification.
Snails failed to shed any cercariae on the first
attempt. On the second attempt, Leptoxis shed
9 cercariae and Pleurocera shed 21 cercariae.
Cercariae from both sets of snails appear
morphologically similar.
Figure1: Snails in beakers under direct lighting
Figure 2: Unstained cercariae from Leptoxis
Figure 3: Unstained cercariae from Pleurocera