A mosquito shortly after obtaining blood from a human (note the droplet of blood plasma being expelled as the mosquito squeezes out excess water). Mosquitos are a<unk>  for several<unk> s, including malaria. In epidemiology, a<unk>  is any living agent that carries and transmits an infectious pathogen to another living organism; agents regarded as<unk> s are organisms, such as parasites or microbes. The first major discovery of a<unk>  came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected a mosquito.
Disease vector
Pathogen
Natural reservoir
Vaccine ingredients
Human parasite
Bioprocess
Pathogenic bacteria
Parasitic worm