National League for Nursing (NLN PAX) Practice Exam

Which of these organisms might be found in contaminated well water?

1. E. coli

2. Giardia

3. Salmonella

4. Vibrio

The correct answer is: Giardia

Giardia is a protozoan parasite that is commonly associated with contaminated water sources, including well water. It can lead to giardiasis, an intestinal infection that causes gastrointestinal symptoms such as diarrhea, cramps, and nausea. Giardia is particularly resilient and can survive in water for extended periods, making it a significant hazard in untreated or poorly managed water systems. Contaminated well water often comes from surface runoff or improper waste disposal, which can introduce Giardia cysts into the water supply. The presence of this organism is an indicator of fecal contamination and the potential presence of other pathogens. While E. coli, Salmonella, and Vibrio can also be found in contaminated water, they have different associations and transmission routes. E. coli is often linked to fecal contamination but is more commonly associated with animal waste. Salmonella is frequently tied to contaminated food rather than water, despite being able to cause illness through contaminated water under certain circumstances. Vibrio species, including Vibrio cholerae, are typically associated with saltwater environments and are more commonly linked to seafood contamination. Thus, Giardia stands out as a typical organism found specifically in contaminated well water, especially in cases where fecal contamination from human or animal sources is suspected.