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).…
Anderson-May host-parasite ODE: dH/dt=rH−βHP; dP/dt=αHP−dP
Anderson-May host-macroparasite framework — the canonical 2-equation coupled ODE model of host-macroparasite population dynamics (Anderson…
R₀ via next-generation matrix: R₀ = ρ(K) = spectral radius; 2×2 NGM = √(a12·a21)
Basic reproduction number R₀ via next-generation matrix framework — the canonical linear-algebraic method for computing epidemic threshold…
Negative-binomial burden: VMR=1+μ/k; aggregation parameter k; overdispersion
Negative-binomial aggregation framework — the canonical probabilistic model of over-dispersed parasite-burden distributions in host…
Anderson-May theorem: H*=d/α; P*=r/β; Tr(J*)=0; det(J*)=rd; eigs=±i√(rd)
Sympy-exact symbolic witness of the Anderson-May host-parasite interior-equilibrium canonical identities. Setup: r, β, α, d — all positive…
R₀ NGM theorem: eigs=±√(a12·a21); R₀=√(a12·a21); R₀_SIR=βH0/(γμ_p); det K=−a12·a21
Sympy-exact symbolic witness of the next-generation matrix R₀ canonical identities. Setup: a12, a21, β, H0, γ, μ_p — all positive symbols.…
NBD theorem: VMR=1+μ/k; σ²=μ(k+μ)/k; Poisson k→∞ VMR=1; geometric k=1; E[X²]
Sympy-exact symbolic witness of the negative-binomial aggregation canonical variance-to-mean identities. Setup: μ, k_agg — positive…
Plasmodium life cycle (Anopheles)
5 species infect humans (P. falciparum / vivax / ovale / malariae / knowlesi); 7-21 day liver + 48h erythrocytic cycles; gametocytes uptake…
Schistosomiasis (Bilharz double-host)
Bilharz 1851 / Manson 1893: Schistosoma life-cycle: adult-worms in human venous-system -> eggs in feces/urine -> miracidium -> snail…
Trichinella spiralis (encysted muscle)
Owen 1835: nematode larvae encyst in striated muscle; transmitted via undercooked pork / wild-boar / bear; trichinellosis with periorbital…
Leishmania (sandfly + amastigote/promastigote)
Donovan 1903 / Leishman 1903: Leishmania flagellated promastigote in sandfly -> amastigote in macrophage of mammalian host; cutaneous +…
Toxoplasma gondii (cat definitive host)
Nicolle-Manceaux 1908: Toxoplasma gondii infects ~30% of humans; cats are definitive host; congenital + immunocompromised reactivation…
Antiparasitic ivermectin (Omura-Campbell)
Omura-Campbell 1979 ivermectin from Streptomyces avermitilis; broad spectrum against nematodes + arthropods; revolutionized onchocerciasis…
Malaria (Laveran 1880)
C Laveran 1880 (Nobel 1907) plasmodium discovery; modern molecular-Plasmodium-falciparum genome 2002 + RTS,S vaccine 2021.
Ross mosquito (1897)
R Ross 1897 (Nobel 1902) Anopheles-malaria vector; modern Sterile-Insect-Technique + gene-drive Anopheles control.
Trypanosomiasis (Bruce 1894)
D Bruce 1894 Trypanosoma brucei tsetse-vector African sleeping-sickness; modern fexinidazole oral-cure 2018.
Toxoplasma (Nicolle 1908)
C Nicolle 1908 (Nobel 1928) Toxoplasma gondii; modern cat-definitive-host + behavioral-manipulation host-parasite hypothesis.
Ivermectin (Ōmura 2015)
S Ōmura-W Campbell 2015 (Nobel 2015) ivermectin onchocerca + COVID-controversy; modern anthelmintic resistance challenges.
Artemisinin (Tu Youyou 2015)
Tu Youyou 2015 (Nobel 2015) artemisinin from Artemisia-annua; modern ACT first-line + emerging-resistance Mekong-Greater.