What occurs during biological transmission of a disease?

During biological transmission of a disease, the microorganism actually multiplies within the host organism. This process typically involves a vector, such as an insect, that harbors the pathogen. When the vector bites or otherwise interacts with a host, the pathogen can enter the host system and, once inside, may replicate or undergo development.

This aspect of biological transmission is important because it often results in a higher pathogenic load being introduced to the new host which can lead to more severe disease outcomes. For example, in the case of diseases like malaria or dengue fever, the disease-causing agents develop within the mosquito before being transmitted to humans, highlighting the critical role of the host in the life cycle of the pathogen. This is distinct from mechanical transmission, where microorganisms are merely transferred from one surface or organism to another without replication.