Humans are the intermediate hosts in which asexual reproduction occurs and female anopheline mosquitos are the definitive hosts harboring the sexual reproduction stage. An infected female Anopheles mosquito begins the cycle by biting a human. Out of about 460 species of Anopheles mosquito, 30-40 species transmit Plasmidium falciparum. One of the best known and most prevalent vectors in Africa is the Anopheles gambiae mosquito.
The infective stage called sporozoites released from the salivary glands through the proboscis of the mosquito enter the bloodstream during feeding. The saliva of the mosquito contains anti-hemostatic and anti-inflammatory enzymes that disrupt blood clotting and inhibit the pain reaction. On average, each infected bite contains 20-200 sporozoites.
Images courtesy of the CDC.https://www.cdc.gov/malaria/images/mosquitoes/anopheles_adult_graph_200w.gif
https://www.cdc.gov/malaria/about/biology/mosquitoes/freeborni_large.html
