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