A fine-tuned vector-parasite dialogue in tsetse's cardia determines peritrophic matrix integrity and trypanosome transmission success.

Arthropod vectors have multiple physical and immunological barriers that impede the development and transmission of parasites to new vertebrate hosts. These barriers include the peritrophic matrix (PM), a chitinous barrier that separates the blood bolus from the midgut epithelia and modulates vector-pathogens interactions. In tsetse flies, a sleeve-like PM is continuously produced by the cardia organ located at the fore- and midgut junction. African trypanosomes, Trypanosoma brucei, must bypass the PM twice; first to colonize the midgut and secondly to reach the salivary glands (SG), to complete their transmission cycle in tsetse. However, not all flies with midgut infections develop mammalian transmissible SG infections-the reasons for which are unclear. Here, we used transcriptomics, microscopy and functional genomics analyses to understand the factors that regulate parasite migration from midgut to SG. In flies with midgut infections only, parasites fail to cross the PM as they are eliminated from the cardia by reactive oxygen intermediates (ROIs)-albeit at the expense of collateral cytotoxic damage to the cardia. In flies with midgut and SG infections, expression of genes encoding components of the PM is reduced in the cardia, and structural integrity of the PM barrier is compromised. Under these circumstances trypanosomes traverse through the newly secreted and compromised PM. The process of PM attrition that enables the parasites to re-enter into the midgut lumen is apparently mediated by components of the parasites residing in the cardia. Thus, a fine-tuned dialogue between tsetse and trypanosomes at the cardia determines the outcome of PM integrity and trypanosome transmission success.

[Effects produced by Spinitectus jamundensis (Nematoda, Cystidicolidae) in the stomach of the shad, Prochilodus lineatus (Pisces, Prochilodidae)]. / Efectos producidos por Spinitectus jamundensis (Nematoda, Cystidicolidae) en el estómago del sábalo, prochilodus lineatus (Pisces, Prochilodidae).

The presence of the nematode Spinitectus jamundensis in cardial and pyloric regions of the stomach of Prochilodus lineatus is observed. Samples of the parasitized stomach were analyzed by histological techniques using Hematoxilin-Eosin and Mallory (Azan) Heidenhain's stainnigs. The macroscopical description of the inner surface of the stomach showing damages in the parasites penetration sites, were observed. Histological observations show that the parasite enters the mucous membrane reaching muscular mucous membrane of the cardial region or the epithelial plaits in the pyloric region reaching up to the muscular layer without crossing it. In this way, the parasite remains confined by a thin layer of connective tissue and in almost direct contact with tissue liquids. Sometimes, in host tissues as response to the parasite presence, an increased level in the amount of lymphocytes in the surrounding tissues is observed.

Esophageal anisakiasis accompanied by reflux esophagitis.

A case with esophageal anisakiasis accompanied by reflux esophagitis is described. A 38-year-old man visited our hospital with complaints of heartburn and disturbance of food passage about seven hours after eating raw cuttlefish. The first esophagogastroscopy revealed an anisakis larva invading the squamocolumnar junction. Near the anisakis larva, a whitish exudate was demonstrated in the distal esophagus just proximal to the squamocolumnar junction. An anisakis larva was easily extracted from the esophagus by forceps. Reflux esophagitis with whitish exudative mucosal lesions and an area of linear erythema more than 5mm long were noted endoscopically 8 weeks after treatment with lansoprazole and cisapride. After six months the third endoscopic examination clarified that there was neither exudate nor erythema in the distal esophagus. Judging from the clinical course that he complained of newly experienced heartburn about seven hours after eating raw cuttlefish, and that whitish exudative mucosal lesions and an area of linear erythema did not disappear at three months after extraction of the anisakis larva. It was concluded that an anisakis larva enters the stomach first and then returns to the esophagus by gastroesophageal reflux.

A typical presentation of a parasitic infestation mimicking a metastatic carcinoma.

A case of ectopic filarial infestation mimicking metastatic oesophageal carcinoma is presented. The clinical implications, pathologic features and pathogenesis of this atypical presentation are discussed.

Stomach parasites of donkeys in Morocco: habitat and interspecific interactions.

One hundred and four donkeys originating from several regions of Morocco were necropsied during 1 year. The parasites in their stomachs were counted and locations determined in the cardiac, fundic and pyloric portions. Synergistic or antagonistic interactions between parasites were assessed by a principal component analysis. Gasterophilus intestinalis was only found in the cardiac portion and G. nasalis was mostly found in the pyloric portion. Habronema were principally encountered in the pyloric portion, whereas Trichostrongylus axei was found in the fundic portion. The parasites were synergistically associated in their habitat interaction, except for T. axei on the fundic portion which was antagonistic to other parasites.

Ultrastructural biology of Leishmania (Viannia) panamensis (=Leishmania braziliensis panamensis) in Lutzomyia gomezi (Diptera: Psychodidae): a natural host-parasite association.

The development of Leishmania (Viannia) panamensis in a natural sand fly host, Lutzomyia gomezi, was studied by light and transmission electron microscopy. New aspects of peripylarian parasite behavior and morphology in the sand fly gut, early bloodmeal stages, and ultrastructural development in the anterior gut were documented. Eight distinct morphological forms were observed in the life cycle of the parasite within the insect. In the bloodmeal, amastigotes (1) transformed into stumpy promastigotes (2) which rapidly multiplied, resulting in spatulate-shaped nectomonad promastigotes (3) and elongate nectomonad promastigotes (4). These latter forms migrated primarily into the hindgut, where both were observed attached (=haptomonad phase) to the cuticular intima by hemidesmosomes within extremely shortened flagella. Spatulate haptomonad promastigotes predominated, colonizing the entire length of the hindgut, with the greatest density at 2 disjunct sites: the pylorus/ileum and the anterior rectum/rectal sac. Paramastigotes and dividing flagellates were rare. Some parasites migrated directly to the cardia/stomodeal valve region without a hindgut phase; however, major movement anteriorly was from the hindgut beginning at 6 days postinfection. In the cardia lumen, dividing short Type A promastigotes (5) predominated, intermixed with short Type B promastigotes with longer flagella (6). Paramastigotes (7) were free-swimming in the lumen as well as attached to the stomodeal valve. The primary colonizers of the valve were pear-shaped haptomonad promastigotes (8), with flagella of variable lengths and multi-segmented hemidesmosomal attachment points to the intima. Promastigotes and paramastigotes colonized the esophagus-pharynx region and attached to the foregut lining by flagellar hemidesmosomes. Both forms may represent infective stages of L. (V.) panamensis; however, no parasites were detected in the cibarium or proboscis. L. (V.) panamensis appeared well-adapted to the gut of Lu. gomezi, multiplying extensively at 2 sites, changing morphological form, and adhering to host surfaces by variously modified flagellar hemidesmosomes.