Final answer:
A reservoir host unaware of the pathogen and spreading the disease is a Carrier, an individual who can transmit the pathogen whether or not they show symptoms.
Step-by-step explanation:
A reservoir host who is unaware of the presence of the pathogen and so spreads the disease is known as a Carrier. This term refers to an active carrier, which is an infected individual who can transmit the pathogen to others regardless of whether symptoms are currently present. This is different from a vector, which is an organism that carries pathogens from one host to another without being infected itself, such as ticks or mosquitoes that transfer diseases like Lyme disease and West Nile virus.