Parasitism arid Pathogenesis 661 



lumhricoides) , human pinworm disease {Enterobius vermicularis) , hook- 

 worm diseases [Necator americanus and Ancylostoma duodenale) ^ 

 ground itch {Ancylostoma hraziliense) , elephantiasis [Wuchereria [Fi- 

 larial bancrojti) , loa loa disease of the eye {Loa loa) , Trichinosis or 

 pork roundworm disease {Trichinella spiralis) , human whipworm disease 

 {Trichuris trichiura) , and many others. 



Worms may cause liver rot of sheep, cattle, and hogs (Fasciola he- 

 patica). Chinese liver flukes may be found in monkeys, cats, dogs, and 

 snails [Clinorchis sinensis) . Blood flukes may be found in monkeys, dogs, 

 cats, pigs, cattle, and sheep (Schistosoma sp.) and lung flukes in dogs, 

 cats, pigs, tigers, and snails [Paragonimus) . Tapeworms may spend their 

 immature stages in the pig, cattle, rabbit, mouse, lice, fleas, fish, sheep, 

 monkeys, cat, dog, etc. "Gid" or "staggers" of sheep is caused by the im- 

 mature stages of the tapeworm (Multiceps) . Horse pinworm disease 

 (Oxyuris equi) may be quite common. "Gapes" of birds is caused by the 

 bird gapeworm {Syngamus trachea). The pork roundworm (Trichi- 

 nella) may inhabit the pig, cat, dog, rat, etc. 



The immature stages of certain mollusks, known as glochidia (glo- 

 kid' i a) (Gr. glochis, arrow-point; idium, diminutive), may attach them- 

 selves to the gills and fins of fish where they may cause diseased condi- 

 tions. Lice and fleas may attack man, dogs, cats, rats, and many other 

 animals, on which they may produce ill effects. Insects may parasitize 

 other insects and even eventually destroy the host. An ichneumon wasp 

 lays eggs in the cocoon of the tent caterpillar, the latter being aff"ected by 

 the developing larval stage of the ichneumon. The eggs of the tachina 

 fly may develop into a larval stage in the army worm; insects of the hy- 

 menoptera type may parasitize boll worms, army worms, plant lice 

 aphids), etc. 



D. Animals Pathogenic for Plants 



Roundworms (nematodes) may attack the roots, stems, or leaves and 

 produce nematode diseases in such plants as wheat, rye, cotton, tomato, 

 clpver, sugar beets, tobacco, peony, begonia, and many other higher 

 plants; the immature stages of the Oriental intestinal fluke {Fasciolopsis) 

 may be present in fresh- water plants; the immature stages of the Chinese 

 liver fluke {Clinorchis) may be present in freshwater plants; the round- 

 worm {Heterodera [Caconema] radicicola) may affect the potato, to- 

 mato, lettuce, trees, weeds, and many other plants. 



