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PetriKey

Disease

Giardiasis

Fatty, foul, floating diarrhea from water

jee-ar-DYE-uh-sis

protozoafecal-oralwaterbornemalabsorptiondiarrhea

High-yield clue

Prolonged non-bloody greasy, fatty, floating diarrhea with bloating after camping or drinking untreated water is the classic giardiasis clue.

Overview

A small-intestine protozoal infection by Giardia, studied for prolonged malabsorptive, non-inflammatory diarrhea and its waterborne fecal-oral spread.

Classification

  • Protozoal enteric syndrome
  • Giardia duodenalis infection
  • Waterborne fecal-oral spread
  • Non-inflammatory and malabsorptive

Lab & identification clues

  • Stool ova-and-parasite cysts/trophozoites vocabulary
  • Stool antigen (EIA) test concept
  • Steatorrhea / fat malabsorption vocabulary

Associations

  • Transmission: untreated water, daycare, fecal-oral
  • At-risk: campers, travelers; chlorine-tolerant cysts
  • Incubation roughly 1-2 weeks vocabulary
  • No blood or pus (non-inflammatory) distinction

Commonly confused with

  • Cryptosporidiosis
  • Amebiasis
  • Lactose intolerance

Frequently asked questions

What is Giardiasis?

A small-intestine protozoal infection by Giardia, studied for prolonged malabsorptive, non-inflammatory diarrhea and its waterborne fecal-oral spread.

What is the high-yield clue for Giardiasis?

Prolonged non-bloody greasy, fatty, floating diarrhea with bloating after camping or drinking untreated water is the classic giardiasis clue.

What is Giardiasis associated with?

Giardiasis is associated with Transmission: untreated water, daycare, fecal-oral; At-risk: campers, travelers; chlorine-tolerant cysts; Incubation roughly 1-2 weeks vocabulary; No blood or pus (non-inflammatory) distinction.

What is Giardiasis commonly confused with?

Giardiasis is commonly confused with Cryptosporidiosis, Amebiasis, and Lactose intolerance.

Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.

OpenStax: Microbiology 2e organism classification foundations - sourceNCBI Bookshelf: Medical Microbiology organism chapters - sourceCDC: CDC disease and public-health topic pages - source