**Question:** Parasites transmitted by ingestion are the following EXCEPT

A. Enteric protozoa (e.g., Entamoeba histolytica, Giardia lamblia)
B. Helminths (e.g., Ascaris lumbricoides, Taenia solium)
C. Viruses (e.g., Hepatitis A virus)
D. Bacteria (e.g., Salmonella typhi, Shigella species)

**Correct Answer:** C. Viruses (e.g., Hepatitis A virus)

**Core Concept:**
Parasites can be transmitted to humans through ingestion of contaminated food or water. There are various types of parasites, including protozoa, helminths, and bacteria. Viruses, however, are not typically considered as parasites and are primarily transmitted through respiratory droplets, fecal-oral route, or close contact.

**Why the Correct Answer is Right:** Viruses are not considered parasites because they do not form a symbiotic relationship with their host. Unlike parasites, viruses rely on the host cell's machinery for their replication and do not have a distinct life cycle within the host. Viruses require direct contact or close proximity for transmission, which is not the case for parasites that can be transmitted through contaminated food or water.

**Why Each Wrong Option is Incorrect:**

A. Enteric protozoa and helminths are examples of parasites that can be transmitted via ingestion, making this option incorrect.

B. Bacteria like Salmonella typhi and Shigella species can cause gastrointestinal infections but are not typically considered parasites. They are classified as enteric pathogens or zoonotic bacteria.

**Clinical Pearl:** To prevent parasitic infections, maintaining proper hygiene, safe water and food handling, and avoiding high-risk areas are essential. Knowledge of the mode of transmission helps prioritize preventive measures and seek appropriate treatment if infected.