Table 31.2.

Common Intestinal Parasites

Parasite	Location in the Host	Clinical Signs/Lesions	Life Cycle
Nematodes
Capillaria	Crop, small intestine, and ceca	Thickened mucosa, emaciation, hemorrhage/anemia	Direct. May be ingested by earthworms.
Dispharynx, Tetrameres, Cyrnea	Proventriculus	Diarrhea, emaciation. Mucosa ulceration, necrosis	Indirect: grasshoppers, cockroaches, sowbugs, and pillbugs are intermediate host
Cheilospirura	Gizzard	Damaged gizzard wall	Indirect: grasshoppers, beetle
Ascarids sp. (Fig. 31.23)	Lumen of small intestine	Weight loss, potential intestinal blockage, and blood loss	Direct: Eggs may be ingested by insects
Heterakis	Ceca	Cecal mucosa inflammation and thickening	Direct: Eggs may be ingested by earthworms
Cestodes	Small intestine	Mild or unknown, except Raillientina sp. that causes severe lesions and weight loss	Indirect: insect, earthworm, snail
Trematode	Small intestine	Mild or unknown	Indirect
Protozoa
Eimeria (Coccidia)	Intestine, region depends on species	Varies with species, from diarrhea to bloody feces and death; from whitish white foci on serosa to hemorrhage and necrosis	Direct
Trichomonas	Esophagus, crop	White-yellow plaques (ulcers)	Direct
Histomonas	ceca, liver	Necrosis	Indirect: Heterakis gallinarum is the initial intermediate host Direct (?)
Cryptosporidium	Small intestine, bursa of Fabricius	Diarrhea, villus atrophy	Direct