The cornerstone for the diagnosis of parasitic infections is a thorough history of the patient's illness. Epidemiologic aspects of the illness are especially important because the risks of acquiring many parasites are closely related to occupation, recreation, or travel to areas of high endemicity. Without a basic knowledge of the epidemiology and life cycles of the major parasites, it is difficult to approach the diagnosis of parasitic infections systematically. Accordingly, the medical classification of important human parasites in this chapter emphasizes their geographic distribution, their transmission, and the anatomic location and stages of their life cycle in humans. The text and tables are intended to serve as a guide to the correct diagnostic procedures for the major parasitic infections; in addition, the reader is referred to other chapters that contain more comprehensive information about each infection (Chaps. 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, and 220). Tables e25-1, e25-2, and e25-3 summarize the geographic distributions, the anatomic locations, and the methods employed for the diagnosis of flatworm, roundworm, and protozoal infections, respectively.
Table e25-1 Flatworm Infections
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Table e25-1 Flatworm Infections
|Parasite||Geographic Distribution||Intermediate (Transmission)||Definitive||Parasite Stage||Body Fluid or Tissue||Serologic Tests||Other|
|Taenia saginata (beef tapeworm)||Worldwide||Beef||Humans||Ova, segments||Feces||—||Motile segments|
|Hymenolepis nana (dwarf tapeworm)||Worldwide||Grain beetles||Humans, micea||Ova||Feces||—||—|
|Diphyllobothrium latum (fish tapeworm)||Worldwide||Copepods–fishb||Humans, other mammals||Ova, segments||Feces||—||Megaloblastic anemia in 1%|
|T. soliumc (pork tapeworm)||Worldwide||Swine||Humans||Ova, segments||Feces||WB||Especially Mexico, Central and South America, Africa|
|Echinococcus granulosus (hydatid disease)||Sheep-raising and hunting areas||Sheep, camels, humans, others||Dogs||Hydatid||Lung, liver||WB, EIA||Chest radiography, CT, MRI|
|E. multilocularis (hydatid disease)||Subarctic areas||Rodents, humans||Foxes, dogs, cats||Hydatid||Liver||—||May resemble cholangiocellular carcinoma|
|T. soliumc (pork tapeworm)||Worldwide||Swine, humans||Humans||Cysticercus||Muscles, CNS||WB||CT, MRI, radiography|
|Fasciolopsis buski||China, India||Snails–water chestnuts||Humans||Ova||Feces||—||—|
|Heterophyes heterophyes||Far East, India||Snails–fish||Humans||Ova||Feces||—||—|
|Metagonimus yokogawai||Far East, Balkans, North Africa||Snails–fish||Humans||Ova||Feces||—||—|
|Clonorchis sinensis||China, Southeast Asia||Snails–fish||Humans||Ova||Feces, bile||—||Recurrent bacterial cholangitis|
|Fasciola hepatica||Sheep-raising areas||Snails–watercress||Humans, sheep||Ova||Feces,d bile||EIA||Cirrhosis, portal hypertension|
|Paragonimus spp.||Orient, Africa, the Americas||Snails–crabs/crayfish||Humans, other mammals||Adults, ova||Lung, sputum, feces||WB, EIA||Chest radiography, CT, MRI|
|Schistosoma mansoni||Africa, Central and South America, West Indies||Snails||Humans||Ova, adults||Feces||EIA, WB||Rectal snips, liver biopsy|
|S. haematobium||Africa||Snails||Humans||Ova, adults||Urine||WB||Liver, urine, or bladder biopsy|
|S. japonicum||Far East||Snails||Humans||Ova, adults||Feces||WB||Liver biopsy|
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