Loasis (Xing. — calabar hypostasis; lat. — loaosis, English — loiasis) is caused by Loa loa microfilarias. The people living in boggy, wet districts get sick mainly. The incubation interval — from several months to several years, proceeds an illness at visitors (not immune) more violently. The helminths which got into a human body can parasitize not only in skin, but also in hypodermic cellulose, and also in a conjunctiva, an anterior chamber of an eye. It also defines features of clinical manifestations of a loasis. A. At localization of helminths in skin and hypodermic cellulose there is a local hypodermic recurrent infiltrate in the form of a swelling size about egg. Skin in this place becomes hotter to the touch, often hyperemic. Emergence of such infiltrate which more often is localized in a wrist and an elbow joint is followed by temperature increase, a skin itch, and is frequent also urtikariya. Hypostasis ("a calabar tumor") can migrate, reflecting movement of helminths, within several months or even years. Each episode of migration lasts from several days to several weeks. In places of localization of helminths in skin abscesses, ulcers can be formed. B. "Calabar hypostasis" can arise in the field of an upper and lower eyelid if helminths get under a conjunctiva. Hypostasis is followed by the expressed local skin itch, a conjunctiva hyperemia. Helminths can get also into an anterior chamber of an eye, and products of their life activity and death cause retina hypostasis. B. If helminths parasitize not in skin, and is deep in hypodermic cellulose, an intermuscular layer, then skin defeats can be absent, and the disease is shown by a periodic joint pain, fever, an eosinophilia. The eosinophilia — an obligatory sign of a loasis during the entire periods, at the same time quantity of eosinophils in blood can reach 70%. Further allergic and autoimmune processes progress, can be a consequence of what a nephrotic syndrome, endo-and myocarditis. The microfilarias which got into brain capillaries can cause their obstruction with the subsequent focal damages; toxic and allergic manifestations strengthen the arisen disturbances. The mass death of microfilarias (and it usually happens against treatment of DEK) can lead to retinal apoplexies.