Onchocerciasis
Onchocerciasis
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DOI：
10.1016/s0140-6736(97)12450-3
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发表时间：
1998-05-02
期刊：
影响因子：
168.9
通讯作者：
Burnham, G
中科院分区：
文献类型：
--
作者：
Burnham, G
Adult worms Adult worms lie inside thick fibrous nodules, being recognised but not seriously attacked by the host’s immune system. The worms probably elaborate substances which promote formation of a rich vascular network around the worm, providing nutrients. 8 Nutrition may come from absorption through a highly convoluted cuticle, as well as from ingested blood. 9 Immediately around the adult worm are macrophages and fibrous proteins. Eosinophils and lymphocytes predominate at the periphery of the nodule, where microfilariae migrating out of the nodule are often attacked. A typical nodule may contain two or three adult female worms (50 cm0· 4 mm), and about half as many males. Itinerant male worms (4 cm0· 20 mm) move from nodule to nodule inseminating the female worms, perhaps attracted by as yet unidentified pheromones. 10 The female worm produces oocytes in large numbers. In the absence of fertilisation, these degenerate within the uterus. 11 When female worms are fertilised, microfilariae develop in 3–12 weeks. Many microfilariae do not successfully escape from the uterus and are reabsorbed.Microfilariae The interval between the bite of an infected fly and the appearance of microfilariae in a person’s skin is 10–20 months. 12 Microfilariae are about 250–300 m long and may live up to two years. 13 They move easily through the skin and connective tissue, ordinarily provoking little reaction while alive and remaining within lymphatic vessels. Their presence has been noted in blood, urine, cerebrospinal fluid, and internal organs. In heavily infected persons 100 million or more microfilariae may be present. 14
