Study of parasites — organisms that live in or on another host, obtaining nutrients at the host's expense. Covers protozoan parasites, helminths, and arthropod ectoparasites; substrate of tropical medicine and veterinary science.
parasitology
Parasitism
Obligate symbiosis in which one organism (parasite) lives at the expense of another (host), reducing host fitness. Distinct from predation…
Protozoan parasite
Single-celled eukaryotic parasites: Plasmodium (malaria, 600k deaths/y), Trypanosoma (sleeping sickness, Chagas), Leishmania…
Helminth (worm) parasite
Multicellular parasitic worms in three groups: nematodes (Ascaris, hookworm, filariae), trematodes (Schistosoma, Fasciola), cestodes…
Parasite life cycle
Sequence of hosts (definitive: sexual stage, intermediate: asexual stage) and environmental stages. Schistosoma: snail → human; Plasmodium:…
Vector-borne disease
Pathogen transmitted by arthropod vector: mosquitoes (malaria, dengue, Zika, WNV), ticks (Lyme, Rocky Mountain spotted fever), tsetse…
Parasite immune evasion
Mechanisms: antigenic variation (Trypanosoma VSG switching, ~1000 gene archive), intracellular residence (Plasmodium in RBCs/hepatocytes),…
Anthelmintic resistance
Evolution of drug resistance in parasitic worms (benzimidazoles, ivermectin) under selection from mass drug administration. Widespread in…
Zoonotic disease
Disease naturally transmissible between vertebrate animals and humans (rabies, Lyme, hantavirus, leptospirosis, SARS/MERS/COVID-19, Ebola).…