What is the most common mode of transmission of Microsporidia?

• A. Contact with body fluids of an infected animal
• B. Ingestion or inhalation of infectious spores
• C. Exposure to pathogen through bites from an infected animal
• D. None of the above

Answer: (B)

Infectious spores are the hallmark of Microsporidia, and these hardy spores are most commonly taken into the body through ingestion or inhalation from contaminated food, water, or dust. Once a spore is swallowed or breathed in, it can invade cells in the gut or respiratory tract and establish infection. Because this environmental exposure route is how spores typically spread, ingestion or inhalation is the best answer. Transmission via body fluids or bites is not the usual route for Microsporidia, and saying none of the above would ignore the established exposure pathway. In practice, controlling exposure means preventing environmental contamination and reducing opportunities for spores to be ingested or inhaled (good hygiene, clean water and feed, dust control, and appropriate PPE).