Disease vector
In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking (hematophagous) arthropods such as mosquitoes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected the stomach tissue of a mosquito.
Source: Wikipedia
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