Advances in PARASITOLOGY VOLUME 4 This Page Intentionally Left Blank Advances in PARASITOLOGY Edited by BEN DAWES Department of Zoology, Kings College, University of London, England VOLUME 4 1966 ACADEMIC PRESS London and New York ACADEMIC PRESS INC. (LONDON) LTD. Berkeley Square House Berkeley Square London, W.l U.S. Edition published by ACADEMIC PRESS INC. 111 Fifth Avenue New York, New York 10003 Copyright 0 1966 by ACADEMIC PRESS INC. (LONDON) LTD. ACtrghs Anobis carGIincrisis Alligator mississippiensis Crocodiles Ewiys orbicuiaris Kittens Author Rodhain and Hoof, 1936 Geirnan, 1937 Rodhain and Hoof, 1935 Ratcliffe and Geiman, 1938 Ratcliffe and Geiman, 1938 Rodhain and Hoof, 1936 Rodhain and Hoof, 1936 Ratcliffe and Geiman, 1938 28 R. A . N E A L in about 2 weeks. The two lizards and one species of tortoise which have been tested were also highly susceptible to infection, with intestinal ulceration. Turtles also proved susceptible to infection, but the infection did not kill the host and intestinal ulceration was not observed (Geiman, 1937). Table VII lists animals which were not susceptible to infection with E. invadens. One frog out of fourteen inoculated with virulent amoebae proved to be infected in the absence of ulceration (Rodhain and Hoof, 1935). Three other frogs were inoculated with culture material from the one infected frog, but these latter frogs were not infected. The amoeba from the one frog was identified as being morphologically identical to E. invadens, and subsequent experiments proved it to be pathogenic for slow-worms (Anguisfragilis). The infectivity studies with the European tortoise Emys orbicularis (Rodhain and Hoof, 1935) were not conclusive. Out of three tortoises inoculated, only one contracted a temporary infection. It is, therefore, included amongst the refractory hosts (Table VII) although, possibly with some justification, it could have been considered susceptible to E. invadens. Reptilian hosts found spontaneously infected with E. invadens are listed by Hill and Neal (1954). The observation that snakes die very quickly after infection with E. invadens suggests that they are not the natural host. Since turtles are easily infected and pass cysts in the faeces, it was thought that these animals could act as carriers (Rodhain and Hoof, 1936). This supposition has now been proved by the identification of E. invadens in the intestine of a turtle (Chrysemys picta) (Meerovitch, 1958). 4. Summary of Host-restriction of Reptilian Amoebae On the basis of present evidence, it can be seen that turtles are infected by two amoebae, E. terrapinae and E. invadens, belonging to the 4-nucleate cyst group of species. Both of these are infective to snakes, one causing lesions and death, E. invadens, and the other living as a commensal in the gut, E. terrapinae. The question of whether these are virulent and avirulent strains of the same species has not been considered, but if they are merely strains differing only in virulence, the situation parallels that of E. histolytica in man. Turtles are also infected by an 8-nucleate cyst species, E. barretti, which is infective to snakes. F . E. ranarum The entamoeba of frogs and toads is called E. ranarum. The morphological resemblance of E. ranarum of the common frog Rana temporaria to E. histolytica prompted Dobell (1918) to attempt to infect tadpoles of Rana temporaria with E. histolytica cysts from man. The tadpoles were not infected. Other studies of the amphibian parasite have been carried out by Cairns (1953) and Lobeck (1940). In addition to results summarized in Table VIII, Cairns found that amoebae from the salamander Ambystoma tigrinum would not infect Triturus pyrrhogaster or the turtle Amyda spinifera. In spite of the extensive work