Final answer:
The mode of transmission through ticks and fleas is called vector transmission, exemplified by Lyme disease, which is caused by the bacterium Borrelia burgdorferi carried by ticks.
Step-by-step explanation:
When a pathogen is transmitted to a susceptible host via ticks and fleas, the mode of transmission is referred to as vector transmission. This is the case with Lyme disease, where the pathogen is the bacterium Borrelia burgdorferi, and the vector is the tick. This method of pathogen transmission is not to be confused with other forms such as fecal-oral transmission or airborne transmission. The presence of such diseases is often related to specific geographic regions where the vector organism is endemic.
Specifically, ticks and mosquitoes are common vectors of pathogens. For example, when a tick carrying Lyme disease bites an uninfected person, it transmits the bacteria that can cause symptoms such as fever, headache, and tiredness. It's important to note that humans are generally dead-end hosts in the transmission cycle of Lyme disease, meaning further transmission from ticks feeding on infected persons is rare.