Final answer:
A host that spreads a disease without showing symptoms is called a carrier. It differs from a vector, which transmits pathogens between hosts, and a fomite, an inanimate object that can indirectly spread pathogens.
Step-by-step explanation:
A reservoir host who is unaware of the presence of the pathogen, exhibits no symptoms of the infection, and spreads the disease is called a carrier. A carrier is an individual who can transmit the pathogen to others regardless of whether symptoms of the infection are currently present. In contrast, a vector is an organism that carries pathogens from one host to another without being infected, such as ticks and mosquitoes. These vectors can either be mechanical, transferring the pathogen without being infected themselves, or biological, wherein the pathogen grows and reproduces in the vector before transmission. A fomite refers to an inanimate object that can transfer pathogens through indirect contact, but it is not considered a host.