Parasitic disease
A disease caused by a parasite living in or on a host. Its agents include protozoa, parasitic worms, and parasitic arthropods.
Host–parasite interaction: The biological relationship between a parasite and the organism it inhabits or exploits. Disease emerges from interactions between parasite traits and the host’s defenses and physiology.
Protozoan infection: An infection caused by a single-celled eukaryotic parasite. Protozoa include agents of malaria, sleeping sickness, and amoebiasis.
Parasitology: The study of parasites, their hosts, and the relationships between them. Parasitology provides the biological basis for diagnosing and controlling parasitic diseases.
Malaria: A mosquito-borne disease caused by Plasmodium parasites. Malaria illustrates a protozoan infection with complex life stages and severe systemic illness.
Bacterial infection: An infection caused by bacteria, single-celled organisms without a nucleus. Bacteria are cellular microbes, unlike the eukaryotic parasites that cause parasitic disease.
Parasite life cycle: The sequence of developmental stages a parasite passes through, often in multiple hosts or environments. Life-cycle stages determine where infection occurs and how parasites reach new hosts.
Helminthiasis: An infection caused by parasitic worms, including flatworms and roundworms. Worm infections form a major class of parasitic disease, often involving chronic tissue or intestinal effects.
Parasitological diagnosis: The identification of parasites or their products in clinical specimens or by other diagnostic methods. Microscopy, antigen tests, and molecular methods can reveal which parasite is causing illness.
Schistosomiasis: A disease caused by blood flukes of the genus Schistosoma. Its transmission through freshwater and chronic organ damage exemplify helminth disease.
Viral disease: A disease caused by viruses that replicate inside host cells. Viruses depend on host-cell machinery and are not classified as parasites in clinical disease categories.