Morphometric and chaetotactic studies were carried out on the body and cephalic regions of the rediae of Fasciola hepatica (Trematoda: Fasciolidae) in order to precisely identify the different redial generations of this trematode in Lymnaea truncatula under experimental infection. At day 49 post-exposure at 20°C, the length of the redia was significantly higher in the first group of the first generation (R1a) compared with successive generations, R1b, R2a and R2b/R3a. The width of the body was similar in the R1a, R1b, and R2a rediae, but was significantly lower in the R2b/R3a groups. The intrapharyngeal cavity of R1a rediae was significantly wider compared with the R1b, R2a, and R2b/R3a groups, whereas the pharyngeal wall was significantly thicker in the R2b/R3a rediae compared with the R1b and R2a groups. Four other measurements, namely the maximum length and width of the pharynx, diameter of the mouth, and width of intestine, also showed significant variations in relation to pharyngeal morphology and age of infection. Discriminant analysis based on these measurements demonstrated that 98% of the rediae were readily categorized into the four groups identified. The number of perioral sensillae ranged from 126 to 160 but a significant difference was only noted between the mean values of the first generation and those of the group R2b/R3a. From these parameters, the maximum width of the pharyngeal lumen was found to be the best characteristic in the identification of the redial generations.

SummaryThe authors present marsh rat Holochilus brasiliensis, jirds Meriones shawi and M. unguiculatus as new models of Schistosoma haematobiurn infection. Histological findings were compared with those of classic models mouse Mus and hamster Mesocricetus. In new models, embryonated eggs were seen in the stool from 90 days post infestation (DPI) and active disease developed from 117 to 175 DPI. Seven out of TO rodents presented granulomatous and/or chronic cystitis, fibrosis, polyps and urothelial changes: squamous metaplasia, precancerous dysplasia and squamous cell carcinoma of the urinary bladder. In the digestive tract of all new models, granulomas eroded the mucosa, formed inflammatory polyps, infiltrated the wall and accumulated into bilharziomas. In the liver, granulomatous hepatitis surrounded by bilharzial pigment deposit was apparent. Pipe-stem fibrosis involved 4 rodents with precirrhotic changes in I and portal hypertension in 2.One female Meriones suffered from granulomatous endometritis and salpingitis. All new models developed pulmonary granulomatosis with associated vascular lesions: giant cell arteritis in I rodent, thromboses in 3 and pulmonary hypertension in 4 others. In classic models, I Mus presented a squamous cell carcinoma of the urinary bladder while Mesocricetus displayed diverse lesions in digestive and genital tracts, liver and lungs. All tissue lesions, resembling those seen in humans in all points, were far more frequent and severe in new models than in classic ones. Those involving the urinary bladder have never been reported in other models such as monkeys: Pan troglodytes, Cercopithecus aethiops and Cebus apella. A comparison was carried out between different models on the basis of experimental conditions: definitive hosts, number of cercariae used, type and duration of infection. This study clearly demonstrated that Holochilus brasiliensis, Meriones shawi and M . unguiculatus are perfectly adequate models in terms of laboratory facilities. They are helpful in investigating the pathogenic mechanism of some disorders in S. haematobium infection, particularly tumours of the urinary bladder, and this may enhance therapeutic assays.

RésuméPoursuivant leur enquête sur les foyers leishm aniens du sud de la France, les auteurs étudient la réceptivité expérim entale et l' infestation spontanée des réservoirs selvatiques. E xpérim entale m ent, les R ongeurs, et particulièrem ent les G liridés, se m ontrent réceptifs aux trois types de L eishm anies, derm otropes et viscéro-tropes (hum aine et canine) ; toutefois, aucune infestation naturelle n'est observée. Par contre, deux R enards, capturés aux lim ites du foyer cévenol, sont trouvés spontaném ent atteints. L 'inoculation d'un broyat de ganglion parasité à deux autres R enards, prove nant d' une région indem ne, est suivie d'infestation. SummaryFollow ing their investigation about the focus of Leishm ania in Southern France, the authors study the experim ental recepti vity and the spontaneous infection of the selvatic reservoirs. E xpe rim entally, the rodents, and particularly the G liridae, appear to b e receptive to the three types of Leishm ania, derm otropic and viscerotropic (hum an and canine) ; how ever no natural infection is observed. O n the other hand tw o foxes captured on the lim its of the C evenol focus w ere found spontaneously infected. T he inoculation of a crushed parasitized lym ph gland to tw o foxes, com ing from an uninfected region, is follow ed by an infection.

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