Final answer:
Malaria and West Nile virus are spread by mosquitoes through a process known as vector-borne transmission, where mosquitoes serve as the vector that carries the pathogen from one host to another.
Step-by-step explanation:
Malaria and West Nile virus are spread by mosquitoes. This type of disease transmission is known as vector-borne transmission. The mosquitoes act as vectors, which are organisms that carry pathogens from one host to another. In the case of malaria, the Anopheles gambiae mosquito carries the Plasmodium falciparum parasite, which it transmits to humans. Similarly, for West Nile virus, the mosquito is the vector that carries the virus and spreads it to humans or animals it bites. Vector-borne diseases are a significant public health concern, particularly in regions where these vectors are prevalent and can spread infectious diseases over wide areas.