Kalu, 30 year old man, presented with subcutaneous itchy nodules over left iliac crest. On examination they are firm, nontender, and mobile skin scrappings contain microfilaria and adult worms of:
Ans. (b) Onchocerca volvulus It is a case of subcutaneous filariasis so causes of lymphatic filariasis (Brugia) and serous cavity filariasis (M.perstans) are ruled out. Thus we left with only 2 options: Loa Loa = Eye Worm: Cause Loiasis/ Fugitive Swellings Or Calabar Swellings Definitive host = Man (in subcutaneous tissue) Intermediate host = Vector - day biting flies (Chyrysops) Mode of trnsmission: Bite of infected Chyrysops Microfilariae: Are sheathed and show diurnal periodicity and appear in blood only during day and taken by chyrysops in which Mf develop into infective third stage larvae. Clinical features: Is due to migration of adult worms causing fugitive swellings (which disappear in few days only to reappear elsewhere); Ocular manifestations. Diagnosis : Demonstration of adult worm from scraping of skin or conjunctiva. Treatment : Surgery to remove worms; DEC; coicosteroids Onchocerca Volvulus: Convulated or blinding filaria causing onchocerciasis or river blindness. It is 2'd major cause of blindness in the world. Vector: Day biting female black flies (are pool feeders) Simulium, which breed in fast flowing rivers. Microfilariae: Unsheathed; non-periodic; found in skin, subcutaneous lymphatics, conjunctiva and rarely in blood. Clinical features: Subcutaneous nodule or onchocercoma which is circumscribed, firm, non-tender tumor tend to occur over anatomical sites where bones are superficial such as scalp, scapula, ribs, elbow, iliac crest, sacrum, knees. Lesions in skin (pruritus, pigmentation, atrophy, fibrosis) and eyes (photophobia to blindness, glaucoma, punctate or sclerosing keratitis, iridocyclitis, glaucoma) also seen. Diagnosis: Demonstrating microfilariae by slicing off a silver of skin; aspirating subcutaneous nodules, conjunctival biopsies. Treatment: Ivermectin; Enucleation of nodules; DEC (cause Mazotti reaction) and Suramin.
Loa loa
Onchocerca volvulus
Brugia malayi
Mansonella persetans