319 



Cheng, Thomas C. 1966. 



Perivascular leucocytosis and other types of cellular reactions in the oyster 

 Crassostrea virginica experimentally infected with the nematode Angiostrongylus 

 aantonensis . J. Invert. Pathol. 8(1): 52-58. 



Conspicuous leucocytic response was observed in oysters 10 to 14 days after 

 infection. Intraluminal nematode larvae attracted extraluminal leucocytes 

 after loth day. The leucocyte-attracting substance was believed to be 

 nematode molting fluid. Infection occurred only when first-stage larvae of 

 nematodes were ingested and penetrated alimentary wall successfully. Larvae 

 can be transported by Leydig tissues of oyster in blood vessels. Mercenaria 

 mercenaria was mentioned by reference to a paper by Cheng and Burton (1965) 

 abstracted elsewhere in this bibliography. - J.L.M. 



320 



Cheng, Thomas C. 1967. 



Marine molluscs as hosts for symbiosis, with a review of known parasites 



of commercially important species. In Advances in Marine Biology, Vol. 5. 



F. S. Russell (edj . Academic Press, London, xiii+424 p. 



Some references to Mercenaria mercenaria in this book are cited from other 

 works, abstracted elsewhere in this bibliography. Only uncited statements 

 are included here. The bird schistosome Austrobilharzia variglandis is 

 found along the Atlantic coast of the United States in Nassarius obsoletus , 

 which shares mud flats with Mya arenaria and Mercenaria mercenaria. People 

 digging clams in such areas may contract "clam diggers itch" or "swimmers 

 itch" from cercarial attack, which produces dermatitis on exposed skin. 

 Large numbers of Himasthla quissetensis cysts have been found in M. mercenaria 

 from Connecticut, and the trematode is suspected, although it was not proven, 

 of causing severe gastrointestinal disturbances in humans. H. muehlensi also 

 has been suspected. Malacobdella mercenaria , a nemertinean, which is 

 identical with M. grossa, has been found in M. mercenaria from Europe and 

 North America, and also in M. campeehiensis . The only known parasites of 

 Mercenaria mercenaria at the time of writing were those already mentioned; 

 Odostomia bisutularis and 0. Seminuda , both induced experimentally; and the 

 copepods Mytilicola porrecta, Myocheres major, and Ostrincola gracilis . 

 (Abstracter's note: Much of this book is devoted to detailed discussions of 

 parasites of commercially important marine mollusks, which include frequent 

 references to such common American bivalves as Crassostrea virginica, Mya 

 arenaria, and Mytilus edulis. It must be concluded either that Mercenaria 

 mercenaria is remarkably free of parasites, or that the species has not been 

 investigated extensively by parasitologists.) - J.L.M. 



321 



Cheng, Thomas C. 19 70. 



Parasites transmittable through waste water to estuarine invertebrates of 

 economic importance and their public health significance. J. Parasitol. 

 56 (4 Sec II Pt. 1) : 54-55. 



Mercenaria mercenaria and Crassostrea virginica from the east coast of the 

 U.S. can serve as experimental intermediate hosts for Angiostrongylus 

 aantonensis , the nematode causative agent of a type of human meningoenceph- 

 alitis in parts of Asia and the South Pacific, although much less effectively 

 than certain other mollusks. It is conceivable that in nature the availa- 

 bility of first-stage larvae of A. aantonensis to susceptible estuarine pele- 

 cypods could be via freshwater runoff contaminated with feces of infected 

 rats. Brackish-water predatory crabs also can serve as paratenic hosts of 

 this nematode. The question needs further study. - J.L.M. 



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