Which term best describes a small animal that transmits disease?

The term that best describes a small animal that transmits disease is "vector." In epidemiology, vectors are typically organisms, often arthropods like mosquitoes or ticks, that carry pathogens from one host to another, thus facilitating the spread of diseases. Vectors do not typically cause the disease themselves but instead serve as vehicles for pathogens, which can infect other organisms.

Understanding the role of vectors is crucial in disease prevention and control, as it allows for targeted strategies to disrupt the cycle of infection. For example, controlling mosquito populations can help reduce the spread of diseases such as malaria or dengue fever.

In contrast, a carrier refers to an organism that harbors a pathogen without necessarily showing symptoms or becoming ill, while a pathogen is the actual microorganism (like bacteria or viruses) responsible for causing disease. A host is an organism that can support the growth and reproduction of the pathogen. Recognizing these definitions helps clarify the specific function of a vector in the transmission of infectious diseases.