This protozoa has a life cycle that involves two stages. One stage in its life cycle is in mosquitoes and the other part of its life cycle is in vertebrate hosts.
At least ten species of plasmodium have been known to infect humans. There are other types that infect other animals though.
When bitten by an infected mosquito the protozoa can be transmitted to the human host through mosquito saliva. Symptoms take anywhere from eight to twenty five days to start. For those on some sort of prevention the symptoms may take longer to set in. Flu like symptoms begin and are followed by feelings of being cold and shivering then fever and sweating.
Of course there are many types of malaria and symptoms are sometimes different from infected to infected.
There are a number of drugs used to aid in preventing the disease, but sometimes the malaria may be immune. Many of those drugs are used in treating the disease too.
The best method of prevention is what's called vector control. The mosquitoes are the carrier so they are considered the vector and keeping their population down is vector control.