Parazitar

Parazitar is a term used to describe organisms or relationships in which one organism, the parasite, lives on or inside another organism, the host, and obtains nutrients at the host's expense. Parazitar relationships can be obligate or facultative and may be internal (endoparasites) or external (ectoparasites).

Endoparasites inhabit internal organs, tissues, or body fluids, while ectoparasites attach to the skin or external surfaces. Common examples include ectoparasites such as fleas, lice, and ticks, and endoparasites such as tapeworms, flukes, roundworms, and protozoa like Giardia. Parasite diversity spans protozoa, helminths, and arthropods, each with distinct life cycles and transmission strategies.

Life cycles often involve transmission between hosts, vectors, or through ingestion of contaminated food or water. Some parasites require multiple hosts or specific environmental conditions to complete development. Complex lifecycles can include stages adapted to different hosts or habitats, illustrating intricate host–parasite interactions and coevolution.

Impact on hosts varies widely. Many parasites cause disease, debilitation, or impaired reproductive success, but some have subtler effects or play roles in ecosystem dynamics, such as regulating host populations or influencing community structure. Host defenses and parasite countermeasures drive ongoing coevolution, shaping immune responses and parasite adaptations.

Diagnosis and control depend on parasite type and context. Medical and veterinary approaches include antiparasitic drugs, sanitation, vector control, safe food and water practices, and protective measures to reduce transmission.

Etymology: from Latin parasita and Greek parasitos, meaning “one who sits beside,” reflecting the parasitic association with a host.