Loinen

Loinen is the Finnish term for a parasite, an organism that lives on or within another organism, the host, from which it derives nutrients and often causes harm. Parasites can be endoparasites, living inside the host, or ectoparasites, feeding on the host from the outside. They may be obligate, requiring a host to complete their life cycle, or facultative, able to live freely but benefiting from a host when available. Parasites infect a wide range of hosts, including humans, other animals, and plants, and they can affect individuals, populations, and ecosystems.

Life cycles of parasites often involve adaptations for transmission and reproduction. Many have one or more intermediate hosts or vectors that help move them between hosts. Parasites may evade or suppress host immune defenses, regulate their own development in response to the host environment, and exhibit a variety of reproductive strategies to maximize survival.

Representative groups include protozoa such as Giardia and Plasmodium, and multicellular helminths like nematodes (eg, Ascaris), cestodes (eg, Taenia), and trematodes (eg, Schistosoma). Ectoparasites such as fleas, ticks, and lice feed on the surface of hosts. Plants can also be parasitized by parasitic plants (eg, dodder) or by parasitic fungi, while some fungi itself act as parasites on crops.

Impact and management are central concerns in medicine, animal health, and agriculture. Parasites can cause disease, reduce productivity, and incur economic costs. Detection methods include microscopy, serology, and molecular tests; treatments comprise antiparasitic drugs and vaccines where available. Prevention emphasizes sanitation, clean water, vector control, and integrated pest management.