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DPDx

DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/ascariasis.

Ascariasis

[Ascaris lumbricoides]

Laboratory Diagnosis

Morphologic Diagnosis

Microscopic identification of eggs in the stool is the most common method for diagnosing intestinal ascariasis. The recommended procedure is as follows:

  • Collect a stool specimen.
  • Fix the specimen in 10% formalin.
  • Concentrate using the formalin–ethyl acetate sedimentation technique
  • Examine a wet mount of the sediment.

Where concentration procedures are not available, a direct wet mount examination of the specimen is adequate for detecting moderate to heavy infections. For quantitative assessments of infection, various methods such as the Kato-Katz can be used. Larvae can be identified in sputum or gastric aspirate during the pulmonary migration phase (examine formalin-fixed organisms for morphology). Adult worms are occasionally passed in the stool or through the mouth or nose and are recognizable by their macroscopic characteristics.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
  • Notice: Linking to a non-federal site does not constitute an endorsement by HHS, CDC or any of its employees of the sponsors or the information and products presented on the site.
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