What are key factors in the epidemiology of parasites in companion animals?

The key factors in the epidemiology of parasites in companion animals include host susceptibility, environmental factors, and transmission routes. Host susceptibility refers to the individual animal's ability to resist infection based on factors like its immune system, age, and overall health. Some animals may be more prone to certain parasitic infections based on their genetic predispositions or health conditions.

Environmental factors encompass a range of conditions such as climate, geography, and the presence of vectors (like fleas, ticks, or mosquitoes) that can facilitate parasite transmission. These conditions influence the lifecycle of parasites and the likelihood of exposure for pets.

Transmission routes involve the methods through which parasites infect host animals, which can vary significantly depending on the parasite's biology. For example, some parasites are transmitted through direct contact, while others may require an intermediate host or specific environmental conditions to thrive.

The other factors mentioned in the other options, while relevant to pet health and wellness, do not encompass the critical elements directly related to the spread and impact of parasitic infections in companion animals as comprehensively as host susceptibility, environmental factors, and transmission routes do.