Infectivity and excystation of the metacercaria of Echinoparyphium flexum (Trematoda)

Observations were made on infectivity and chemical excystation of the metacercaria of Echinoparyphium flexum (Trematoda) obtained from naturally infected Physa heterostropha snails in Cumberland County, Pa. Domestic chicks fed large numbers of cysts revealed an infectivity rate of about 2%. Regardless of the worm burden in chicks, flukes localized only in the upper region of the small intestine. Attempts to increase infectivity by treating cysts in various pretreatment solutions were unsuccessful. Cloacal inoculation of chicks with chemically excysted metacercariae also failed to produce infection. In vitro excystation experiments revealed that the synergistic effect of bile salts + trypsin at an alkaline pH produced maximal excystation at 420C within 30 min, and cyst pretreatment in acidified-pepsin was not
a prerequisite for excystation.

Title	Infectivity and excystation of the metacercaria of Echinoparyphium flexum (Trematoda)
Creator	Fried, Bernard
Creator	Grigo, K. L.
Publisher	Proceedings of the Pennsylvania Academy of Science
Academic Department	Biology
Division	Natural Sciences
Organization	Lafayette College
Date Issued	1975
Date Available	2015-03-17T17:40:05Z
Type	Article
Language	English
Bibliographic Citation	Fried, B. and K. L. Grigo (1975) "Infectivity and excystation of the metacercaria of Echinoparyphium flexum (Trematoda)." Proceedings of the Pennsylvania Academy of Science 49 (1): 79-81.
Standard Identifier	Handle 10385/1728
Permalink	http://hdl.handle.net/10385/1728
Rights Statement	In Copyright
Rights Holders	Pennsylvania Academy of Science, Inc.