Mosquitoes become infected with malaria when they bite a host animal that has the disease, and suck the infected blood up into their abdomen to be digested as food.
They then spread malaria to another animal or person when they go in search of another blood meal, which allows them to reproduce again, and bite that animal, exposing it to malaria.
Mosquitoes are one of the most dangerous insects in the world, and are prolific vectors for diseases such as malaria and dengue fever, although they cannot spread the AIDS virus.
Malaria, chiefly spread by mosquitoes bites, is an epidemic in many developing countries of the world.