Gastroenteritis%20-%20parasitic Diagnosis

• Attempt to elicit a history of possible exposure, especially for helminthic infections (eg eating undercooked meat, ingestion of undercooked or raw fish, swimming in fresh water where certain parasites may be endemic, walking barefoot)
• Knowledge of the geographic distribution of parasites is helpful in the diagnosis

• Findings are nonspecific

Microscopic Exam of Stools

• Fundamental to the diagnosis of all gastrointestinal parasitic infections
  
  • A minimum of 3 stool specimens, examined by trained personnel using a concentration and a permanent stain technique, should be used
  • The stool exam is used to detect protozoan cysts and trophozoites, helminth ova, proglottids, larvae or adult worms
  • A fecal sample must be mixed well before examination because eggs are never uniformly distributed in feces

Other Laboratory Tests

• The following are other tests that may be used to document a parasitic infection, as necessary
  
  • Duodenal aspirate
  • Biopsy
  • String capsule test
  • Immunofluorescent antibody test
  • Enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR)
  • Cellophane tape test
  • Barium studies
• Anemia and eosinophilia may be seen on the complete blood count (CBC)
  • Eosinophilia may be seen especially with helminthic infections
  • Anemia may be seen especially in severe cases of hookworm infection
• Sudan stain for malabsorption
• Liver biopsy, abdominal imaging studies (eg abdominal ultrasound, computerized axial tomography scan) may be considered as supportive evidence in patients with suspected Fasciola hepatica infection