Parasitresistens

Parasitresistens, or resistance of parasites to antiparasitic drugs, is the reduction in efficacy of treatments used to control parasitic infections in humans, animals, and plants. It arises when parasite populations adapt to drugs, enabling survival and reproduction despite treatment.

Causes include extensive or improper use of antiparasitics, under-dosing, and lack of refugia. Resistance develops through genetic changes such as mutations in drug targets, gene amplification, altered drug transport, and metabolic pathway changes. Parasites with complex life cycles and high fecundity spread resistance quickly.

Common contexts include livestock production, aquaculture, and human medicine for helminths and protozoa. Documented examples include resistance of intestinal nematodes to benzimidazoles and of other parasite groups to macrocyclic lactones and nitroimidazoles in various regions.

Detection methods include phenotypic assays such as fecal egg count reduction tests and molecular diagnostics that identify resistance-associated mutations. Surveillance networks track trends to guide treatment choices and policy.

Management emphasizes drug stewardship and integrated measures: correct dosing, rotating or combining drug classes, maintaining refugia, targeted selective treatment, improved farm and water management, vaccination where available, and investment in new antiparasitics and vaccines.

Impact and outlook: resistance reduces treatment efficacy, increases disease burden and costs, and can threaten food production and public health. Coordinated research and policy efforts are needed to slow resistance, preserve drug options, and promote sustainable parasite control.