Schistosomiasis is a water-borne parasitic illness caused by neoophoran trematodes of the genus Schistosoma. Using classical histological techniques and whole-mount preparations, the present work describes the embryonic development of Schistosoma mansoni eggs in the murine host and compares it with eggs maintained under in vitro conditions. Two pre-embryonic stages occur inside the female worm: the prezygotic stage is characterized by the release of mature oocytes from the female ovary until its fertilization. The zygotic stage encompasses the migration of the zygote through the ootype, where the eggshell is formed, to the uterus. Fully formed eggs are laid still undeveloped, without having suffered any cleavage. In the outside environment, eight embryonic stages can be defined: stage 1 refers to early cleavages and the beginning of yolk fusion. Stage 2 represents late cleavage, with the formation of a stereoblastula and the onset of outer envelope differentiation. Stage 3 is defined by the elongation of the embryonic primordium and the onset of inner envelope formation. At stage 4, the first organ primordia arise. During stages 5 to 7, tissue and organ differentiation occurs (neural mass, epidermis, terebratorium, musculature, and miracidial glands). Stage 7 is characterized by the nuclear condensation of neurons of the central neural mass. Stage 8 refers to the fully formed larva, presenting muscular contraction, cilia, and flame-cell beating. This staging system was compared to a previous classification and could underlie further studies on egg histoproteomics (morphological localizome). The differentiation of embryonic structures and their probable roles in granulomatogenesis are discussed herein.

Seeking the identification ofA. cantonensis has already been found in Southeast Asia, South Pacific, Africa, India, Caribbean, Australia, North America (Pien & Pien 1999), Jamaica (Lindo et al. 2002) and Haiti (Raccurt et al. 2003).Eosinophilic meningitis is a rare clinical entity that is defined by the presence of 10 or more eosinophils/ ml in the cerebrospinal fluid (CSF) or a CSF eosinophilia of at least 10% of the total CSF leukocyte count (Kuberski 1979). The most common cause is invasion of the central nervous system by helminthic parasites, inciting an inflammatory response that eventually kills the parasites. Clinical manifestations, which develop in humans at two to 35 days after larvae ingestion, may include headache, nuchal rigidity and visual disturbances (Koo et al. 1988). Cerebral angiostrongyliasis usually has an incubation period of about two weeks, although it may vary from 12 to 28 days (Dooley & Neafie 1976). Paresthesias of the extremities, trunk or face, are the most distinctive neurological findings and can persist for weeks to months after the other symptoms are resolved. Occasionally, infective larvae can migrate to the eye, causing retinal detachment or intraocular hemorrhage, but most patients recover completely (Alicata 1962, Sawanyawisuth et al. 2007. In Brazil, a clinical case of eosinophilic meningoencephalitis that resulted in death ten days after ingestion of three Achatina fulica snails was reported in a regional meeting in 2006 (AVS Moll, G Zanini and C Graeff-Teixeira, unpublished observations).In January 2007, two male individuals aged 21 and 39 years were admitted to the local hospital of Cariacica, state of Espírito Santo (ES), Brazil, with eosinophilic meningitis and history of ingestion of raw terrestrial slugs. By that time, a male child aged one year and eight months from the city of Vila Velha, ES, had also been admitted to the hospital with similar symptoms.A number of 270 mollusc specimens and feces from Rattus norvergicus were collected with a grasping tool, in peridomiciliary areas of the patients' houses by health agents of the Central Laboratory of the ES (LACEN-ES). The materials were sent to the Laboratory of Intestinal Helminthiasis of Instituto René Rachou-Fiocruz for mollusc morphological identification and molecular characterization of nematode larvae. The gastropods were identified as: Sarasinula marginata (Semper, 1885) (Veronicellidae), 45 specimens, Subulina octona (Bruguière, 1792) (Subulinidae), 157 specimens, A. fulica (Bowdich, 1822) (Achatinidae), 45 specimens, and Bradybaena similaris (Férussac, 1821) (Bradybaenidae), 23 specimens.

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Classical schemes of the adult Schistosoma mansoni reproductive system have been described. In our study, whole adult worms derived from unisexual or mixed infections and stained with carmine chlorine were virtually and tomographically analyzed under confocal laser scanning microscopy. We found that: (1) there were morphological differences in the ovary, vitteline glands and testicular lobes between specimens derived from unisexual or mixed infections; (2) there was always a single lobed ovary (three or four lobes), presenting differentiation from the anterior to the posterior lobes, where the most mature oocytes were located; (3) the proximal segment of oviduct was connected to an ampullary dilatation, full of tailed spermatozoa, characterizing a seminal receptacle; (4) there was no long vitelline duct, but a short one that begins at the end of the proximal region of the vitelline gland; (5) long cells of Mehlis' gland placed radially around the ootype were not observed. Otherwise, the ootype was only lined by thick cuboidal epithelial cells with plaited bases and nuclei with flabby chromatin, making a clear distinction from the uterine epithelium. This morphological feature suggests that each cell represents a gland. (6) In coupled males, the specimens located inside the gynaecophoric canal had smaller testicular lobes, suckers, and body length and width when compared to their partners. Our results show that the reproductive system does not follow a unique pattern within flatworms. Due to its better resolution, confocal laser scanning microscopy, using a reflected mode with tomographic sections, allows new interpretations, modifying the adopted and current descriptions of the internal morphological structures of S. mansoni adult worms.

Epimastigotes multiplying extracellularly and metacyclic trypomastigotes, stages that correspond to the cycle of Trypanosoma cruzi in the intestinal lumen of its insect vector, were consistently found in the lumen of the anal glands of opossums Didelphis marsupialis inoculated subcutaneously with infective feces of triatomid bugs.