You get malaria from a bite by an infected mosquito. This bite injects malaria-causing parasites into your blood, where they travel to liver cells. In the liver cells, the parasites breed. The cells later burst, letting loose thousands of new parasites that go on to infect more red blood cells.

Mosquitoes get malaria from biting a human who has malaria. The mosquito draws the blood into its stomach where malaria parasites breed and infect other red blood cells. In time, the parasites move into the mosquito’s salivary glands. When this happens, the mosquito is then able to infect a human.