Parasitic disease

Close-up of a Plasmodium, which causes Malaria. Mosquitoes spread malaria through their bite.

A parasitic disease is a disease caused by a parasite. It is also known as parasitosis. Parasites live on or inside a host organism, and they cause harm to the host. Parasites are either protozoa, parasitic worms (called helminths), or parasitic arthropods. Other parasites that cause disease include lice, fleas, mites, and certain fies, which are know as ectoparasites.