A fly contaminating food with pathogens from fecal matter and transmitting to a new host is an example of which vector type?

• A. Mechanical vector
• B. Biological vector
• C. Reservoir
• D. Direct contact

Answer: (A)

The key idea is how a pathogen is transmitted by a vector. In a mechanical vector, the pathogen is carried passively on the body or parts of the vector without the pathogen needing to multiply or develop inside the vector. Here, the fly picks up pathogens from fecal matter and contaminates food, passing them to a new host without the pathogen undergoing any development inside the fly. That makes it a mechanical vector.

If it were a biological vector, transmission would require the pathogen to develop or multiply within the vector before being transmitted, which isn’t the case here. A reservoir is simply the environment or organism where the pathogen persists, not the act of transferring it via a vector. Direct contact involves direct person-to-person transfer without an intermediary organism like a fly.