Direct wet mount is commonly used to screen for which of the following intestinal parasites?

• A. Giardia lamblia
• B. Plasmodium falciparum
• C. Ascaris lumbricoides
• D. Taenia solium

Answer: (A)

Direct wet mount is most effective for spotting Giardia lamblia because Giardia is readily identified in a fresh stool sample by the observation of motile trophozoites in a saline preparation. The trophozoites have a distinctive pear shape and active flagellar movement, which makes them stand out quickly in a direct mount. Plasmodium falciparum is a malaria parasite found in blood, not stool, so it isn’t detected this way. While Ascaris lumbricoides and Taenia solium eggs can be seen in stool, they’re often better detected with concentration techniques; a direct mount is not the standard screening method for them.