loa is long-lived (> 20 years) and adult females can produce 12,000-39,000 microfilariae per day, primary prevention is focused on reducing the near-constant exposure to the Chrysops spp. Disease manifestations, therefore, may not occur until 6-18 months from the time of inoculation. Once within the human host, the maturation process from 元 larvae to adult nematode is estimated to require 150-170 days. The microfilariae mature through the third larval stage (元) within the fly, migrate to the proboscis, and enter a new host via a subsequent blood meal, where they mature into adult nematodes. Their diurnal activity coincides with that of the Chrysops fly, increasing their likelihood of ingestion during a blood meal. Microfilariae are sheathed and can be found in the spinal fluid, urine, sputum, lungs, and blood of an infected individual. Loa loa is transmitted by the deerfly of the Chrysops genus, which demonstrates a diurnal pattern of activity, being most active from 10 am - 2 pm. This theory also explains the mechanism of retinal vessel involvement in Loa loa retinopathy, and might readily be applied to other organ systems. It is hypothesized that this increased risk of mortality is due to obstructive or inflammatory processes within the circulation. However, the view of loiasis as a benign disease has been called into question by the finding that the population-attributable fraction of mortality associated with Loa loa microfilaremia is 14.5%. A primary cause for concern has been the risk for encephalopathy and other severe adverse reactions when ivermectin is administered to individuals who are coinfected with Loa loa and Onchocerca volvulus. Loiasis has traditionally been regarded as a benign condition. Cutaneous manifestations including Calabar swellings are also pathognomonic and are likely due to a hypersensitivity response elicited by migration of the adult worm through tissue. Eyeworm is a pathognomonic finding in the disease course and occurs when the adult worm is visualized migrating beneath the bulbar conjunctiva. Loiasis is an infection of the submucosal and subcutaneous tissue caused by the filarial nematode Loa loa.
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