Parasyty

Parasyty is a term used to refer to parasites — organisms that live on or in another organism (the host) and obtain nutrients or other benefits at the host's expense. Parasites range from microscopic protozoa and bacteria to multicellular helminths (worms) and arthropods (ticks, fleas). They occur across virtually all ecosystems and affect plants, animals and fungi as hosts.

Parasites are categorized by habitat (ectoparasites live on the host surface; endoparasites live inside tissues or organs), by dependence (obligate parasites require a host to complete their life cycle; facultative parasites do not), and by life-history strategy (parasitoids eventually kill their hosts, while typical parasites usually do not). Life cycles can be direct, with a single host species, or complex, involving multiple hosts and vectors that transmit infectious stages.

Ecologically, parasites influence host population dynamics, community structure and coevolutionary processes. They can regulate host abundance, alter behavior, and affect nutrient cycles. In human and veterinary contexts, parasitic infections cause significant disease burden and economic costs; examples include malaria (Plasmodium spp.), schistosomiasis, and various helminthiases.

Control measures combine prevention (sanitation, vector control, vaccines where available), diagnosis and treatment with antiparasitic drugs, and integrated management in agriculture and public health. Ongoing research addresses parasite genomics, drug resistance, vaccine development and the role of parasites in ecosystems and One Health frameworks that link human, animal and environmental health.