What is passive or mechanical transmission in disease spread?

Passive or mechanical transmission refers to the way diseases are spread without the involvement of a biological change or multiplication of a pathogen inside the carrier organism. In this context, the correct answer highlights that transmission happens through unintentional contact. This type of transmission occurs when a vector, such as an insect, physically carries a pathogen on its body (like on its legs or mouthparts) and transfers it to a host, often without the vector acquiring any infection itself.

For instance, if a fly lands on contaminated food, it can facilitate transmission to humans when they consume that food, without being a true vector that multiplies the pathogen. This method stands in contrast to other options, which involve active or more complex roles in the disease transmission process.