Cruz Ligia M, Allanson Michael, Kwa Boo, Azizan Azliyati, Izurieta Ricardo
Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida 33612, USA.
J Parasitol. 2012 Feb;98(1):63-8. doi: 10.1645/GE-2821.1. Epub 2011 Jul 29.
Information on the infective stage of Ascaris lumbricoides and the pathology caused by the parasite is widely available in the literature. However, information about early embryonic development of A. lumbricoides and its life cycle outside the host is limited. The purpose of this study was to describe the morphological changes within the developing embryo during incubation in vitro at 28 C, as well as to explore differences in egg viability during incubation. Ascaris suum eggs (4,000 eggs/ml), used as a model for A. lumbricoides , were placed for incubation in 0.1N H(2)SO(4) at 28 C in the dark for 21 days. Every day, sub-samples of approximately 100 A. suum eggs were taken from the incubation solution for microscopic evaluation. Development, morphological changes, and viability of the first 40 eggs were observed and documented with photos. During this study, 12 stages were identified in the developing embryo by standard microscopy, 2 of which had not been previously reported. By the end of the first wk, most developing embryos observed were in the late-morula stage (72.5%). On day 14 of incubation, 90% had developed to larva-1 stage, and by day 21, 100% had developed to larva-2 stage. No significant differences were found in the viability recorded in a continuum from day 5 to day 21 of incubation (chi-square, P > 0.05). The result of this study complements and expands the stages of development of Ascaris spp. outside the host previously reported in the literature. It also suggests the potential use of early stages of development of the nematode to determine viability and safety of sewage sludge, wastewater, or compost after treatment recommended by USEPA.
关于蛔虫感染阶段以及该寄生虫所致病理学的信息在文献中广泛可得。然而，关于蛔虫早期胚胎发育及其在宿主体外生命周期的信息有限。本研究的目的是描述在28℃体外孵育期间发育中胚胎的形态变化，以及探索孵育期间虫卵活力的差异。用作蛔虫模型的猪蛔虫卵（4000个卵/毫升）置于0.1N硫酸中，于28℃黑暗条件下孵育21天。每天从孵育液中取约100个猪蛔虫卵的子样本进行显微镜评估。观察并拍摄了前40个虫卵的发育、形态变化和活力情况。在本研究中，通过标准显微镜在发育中的胚胎中鉴定出12个阶段，其中2个阶段此前未见报道。在第一周结束时，观察到的大多数发育中胚胎处于桑葚胚晚期（72.5%）。孵育第14天时，90%已发育至幼虫1期，到第21天时，100%已发育至幼虫2期。在孵育第5天至第21天的连续过程中记录的活力未发现显著差异（卡方检验，P>0.05）。本研究结果补充并扩展了文献中先前报道的蛔虫在宿主体外的发育阶段。它还表明线虫发育早期阶段有可能用于确定美国环境保护局推荐的处理后污水污泥、废水或堆肥的活力和安全性。
