Trpis M, Wergin W P, Murphy C A
The Johns Hopkins University, School of Hygiene and Public Health, The W.H. Harry Feistone Department of Molecular Microbiology and Immunology, Baltimore, Maryland 21205-2179, USA.
J Parasitol. 2001 Dec;87(6):1265-72. doi: 10.1645/0022-3395(2001)087[1265:DOOVFO]2.0.CO;2.
Simulium yahense black flies infected with microfilaria of Onchocerca volvulus were kept in a defined insectary environment in Liberia, West Africa. A daily sample of infected flies was dissected for larvae developing in the thoracic muscles and examined for growth in stadial development. Microfilariae ingested by black flies transformed to the L1 larval stage without molting. Successive larval development included molting to the L2 stage and, finally, to the L3 stage, which was infective in humans. The cephalic cap, consisting of a laterally located hook and central stoma, occurs in the first larval stage. The caudal appendix and the laterally located anal opening are apparent in the L1 larva. In the L2 stage, the cephalic cap is lost and the large circular stoma becomes surrounded with elevated flaps. The caudal appendix was lost after larvae molted to the L3 stage, and in its place, 3 terminal papillae developed. Sense organs, such as 2 opposing phasmids and 8 papillae that were arranged into 2 circles, developed in the cephalic region of the L3 larva. The evidence of pathological consequences due to the presence of the L3 larva in the fly host are illustrated and discussed.
感染了盘尾丝虫微丝蚴的雅氏蚋被饲养在西非利比里亚一个特定的昆虫饲养环境中。每天对感染的蚋进行解剖，以检查胸肌中发育的幼虫，并观察其在龄期发育中的生长情况。被蚋摄取的微丝蚴未经过蜕皮就转变为L1幼虫阶段。随后的幼虫发育包括蜕皮至L2阶段，最终蜕皮至对人类具有感染性的L3阶段。头部帽状体由侧向的钩子和中央口组成，出现在第一幼虫阶段。尾附器和侧向的肛门开口在L1幼虫中很明显。在L2阶段，头部帽状体消失，大的圆形口被隆起的瓣包围。幼虫蜕皮至L3阶段后尾附器消失，取而代之的是3个末端乳头。感觉器官，如2个相对的尾感器和排列成2个圆圈的8个乳头，在L3幼虫的头部区域发育。文中展示并讨论了由于L3幼虫存在于蚋宿主中而导致的病理后果的证据。
