Which parasite's eggs can be ingested from fecally contaminated water leading to infection?

Which parasite's eggs can be ingested from fecally contaminated water leading to infection?

• A. Ascaris lumbricoides
• B. Entamoeba histolytica
• C. Taenia solium
• D. Giardia lamblia

Answer: (A)

The infective form is an embryonated egg that resists environmental conditions, making fecal-oral transmission via contaminated water a classic route. Ascaris lumbricoides sheds eggs in human feces; these eggs contaminate water and become embryonated in the environment. When ingested through dirty water, the eggs release larvae in the gut, migrate to the lungs, then return to the intestine to mature into adult worms. This life cycle hinges on ingestion of eggs from contaminated water, which is why it’s the best answer. Giardia lamblia and Entamoeba histolytica rely on cysts, not eggs, for infection, even though waterborne transmission can occur. Taenia solium eggs can also be ingested and cause disease, but the most straightforward and classic example of waterborne infection via eggs points to Ascaris lumbricoides.

The infective form is an embryonated egg that resists environmental conditions, making fecal-oral transmission via contaminated water a classic route. Ascaris lumbricoides sheds eggs in human feces; these eggs contaminate water and become embryonated in the environment. When ingested through dirty water, the eggs release larvae in the gut, migrate to the lungs, then return to the intestine to mature into adult worms. This life cycle hinges on ingestion of eggs from contaminated water, which is why it’s the best answer.

Giardia lamblia and Entamoeba histolytica rely on cysts, not eggs, for infection, even though waterborne transmission can occur. Taenia solium eggs can also be ingested and cause disease, but the most straightforward and classic example of waterborne infection via eggs points to Ascaris lumbricoides.