The Experts below are selected from a list of 3105 Experts worldwide ranked by ideXlab platform
Daniel Rondelaud - One of the best experts on this subject based on the ideXlab platform.
-
Fasciola hepatica: the Redial generations in juvenile Pseudosuccinea columella
Parasitology research, 2015Co-Authors: Y. Dar, Daniel Rondelaud, Philippe Vignoles, Gilles DreyfussAbstract:Juvenile Pseudosuccinea columella, measuring 1 or 2 mm in height, were subjected to single-miracidium infections with Fasciola hepatica to determine the developmental pattern of Redial generations and count free and live Rediae according to their generation. Controls were constituted of juvenile Galba truncatula infected according to the same protocol. In the four groups, Redial counts were performed in snails dissected every week from day 7 to day 49 post-exposure at 20 °C. Most infected snails showed a normal development of Redial generations, whatever the lymnaeid species. In P. columella, the total number of live Rediae on day 49 was 24.6 and 34.6 per infected snail in the 1 and 2-mm groups, respectively (instead of 11.5 and 18.8 Rediae in the corresponding groups of G. truncatula). A single mother Redia (R1a) producing only daughter Rediae of the second generation was noted in each snail of three groups, while the 2-mm P. columella showed the presence of a single (43 snails/71) or two (28/71) R1a Redia(e) within their bodies. The mean number of other mother Rediae and that of daughter Rediae of the second generation were low in the 1 and 2-mm groups of both lymnaeids. Besides, there was a delay in Redial development. The development of two live R1a Rediae in several P. columella from the 2-mm group needs to verify if this process would be specific to P. columella or would occur in other lymnaeid species known for their good susceptibility to the digenean and their larger size to allow harbouring Rediae.
-
Growth rate of the intermediate snail host Galba truncatula influences Redial development of the trematode Fascioloides magna.
Journal of Helminthology, 2013Co-Authors: Daniel Rondelaud, Philippe Vignoles, A. Novobilský, J. Höglund, M. Kašný, J. Pankrác, Gilles DreyfussAbstract:A total of 850 pre-adult Galba truncatula (shell height, 4 mm), originating from four French snail populations differing in shell height at the adult stage (from 6.5 to 12 mm), were individually subjected at 20°C to single-miracidium infections with Fascioloides magna. At day 75 post-exposure, the surviving snails were dissected, and Rediae and cercariae were counted. Snail groups differed in shell growth during the experiment: from 1.8 ± 0.4 mm in group A up to 4.0 ± 1.1 mm in group D. The prevalence of F. magna infection, the numbers of free Rediae and cercariae significantly increased together with increasing growth of infected snails during the experiment. Group A produced 1-6 first-generation Rediae per snail and the mean daughter Redia production ranged from 7.5 second-generation Rediae (when a single first generation per snail developed) to 2.3 (6 first-generation Rediae per snail). In contrast, up to ten first-generation Rediae were noted in group D, and each mother Redia gave daughter Rediae with averages ranging from 1.5 (ten first-generation Rediae per snail) to 13 (a single first generation per snail). In conclusion, the development of F. magna in G. truncatula exhibited both inter- and intrapopulation variability, where the development of Rediae and cercariae was positively correlated with snail growth.
-
The development of Rediae of Fasciola hepatica in Radix natalensis subjected twice to bimiracidial exposures.
Journal of Helminthology, 2010Co-Authors: Y. Dar, G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Egyptian Radix natalensis with a French isolate of Fasciola hepatica (each snail was subjected twice to a bimiracidial exposure) were carried out to determine how many sporocysts grew in these snails and to study the developmental patterns of Redial generations. Single-sporocyst infections were found in 69.3% (34/49) of infected snails, with equivalent numbers of normal and abnormal patterns. Snails with two- and three-sporocyst infections were 24.4% and 6.1%, respectively. In single- and two-sporocyst infections at days 42 and 56 post-exposure, the total Redial burden was significantly higher in snails with a normal Redial development. In two- and three-sporocyst infections, the overall maturity of Rediae was delayed at days 42 and 56. The high frequency of abnormal patterns in R. natalensis (53.1% of all infected snails showed degeneration of a first mother Redia) might be due to incomplete adaptation between the snail population and the parasite. The delayed Redial maturity in two- and three-sporocyst infections can mainly be explained by the volume of the snail body, which would be insufficient to allow the simultaneous differentiation of most Rediae over time.
-
Redial generations of Fasciola hepatica: a review.
Journal of Helminthology, 2009Co-Authors: Daniel Rondelaud, Philippe Vignoles, M. Belfaiza, M. Moncef, Gilles DreyfussAbstract:An update on the Redial generations of Fasciola hepatica was carried out to highlight the different developmental patterns of Rediae, the effects of some factors on these generations, and the consequences of such developmental patterns on cercarial productivity. The development of generations is dependent on the behaviour of the first mother Redia of the first generation. If this Redia remains alive throughout snail infection, it produces most second-generation Rediae. In contrast, if it dies during the first weeks, daughter Redia formation is ensured by a substitute Redia (the second mother Redia of the first generation, or the first Redia of the second generation). Environmental and biotic factors do not modify the succession of Redial generations, but most act by limiting the numbers of Rediae, either in all generations, or in the second and/or third generations. An abnormal development of Rediae reduces the number of cercariae and most are formed by the second cohort of the first generation. By contrast, most cercariae are produced by the first cohort of the second generation when Redial development is normal. The mother Rediae described by previous authors might correspond to the first generation and the second cohort of the second generation, while daughter Rediae would be the second cohort of the second generation and the first cohort of the third generation. Under certain circumstances, daughter Redia formation is ensured by the first two mother Rediae or all first-generation Rediae, thus demonstrating that the first mother Redia is not the only larva to ensure daughter Redia formation.
-
Paramphistomum daubneyi: the number of sporocysts developing in experimentally and naturally infected Galba truncatula.
Parasitology Research Journal of Parasitology, 2008Co-Authors: G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out to determine at day 50 (at 24 degrees C) the numbers of sporocysts, which grew in infected snails via the count of first- and second-generation Rediae. In snails individually exposed to one, two, three, four, or five miracidia, the numbers of first-generation Rediae increased from the one-miracidium group to the five-miracidium snails (from a mean of 6.7 to 26.1), while second-generation Rediae decreased in number (from 6.2 to 0.9, respectively). This scale of Redial numbers was used to determine the number of sporocysts, which grew in naturally infected snails collected from sedimentary or acid soils between 1993 and 2006. In cercariae-containing snails, natural infections resulting from the development of one to five sporocysts were found in both samples of G. truncatula examined. The numbers of 3-, 4-, and 5-sporocyst infections were increasing over time since 1997, 2000, and 2003, respectively. The utility of such multiple-sporocyst infections is open to question, as the differentiation of second-generation Rediae and that of procercariae were delayed and always limited. They might be interpreted as a consequence of a zoonosis, which has been spreading since 1990 in ruminants of central France.
G Dreyfuss - One of the best experts on this subject based on the ideXlab platform.
-
The development of Rediae of Fasciola hepatica in Radix natalensis subjected twice to bimiracidial exposures.
Journal of Helminthology, 2010Co-Authors: Y. Dar, G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Egyptian Radix natalensis with a French isolate of Fasciola hepatica (each snail was subjected twice to a bimiracidial exposure) were carried out to determine how many sporocysts grew in these snails and to study the developmental patterns of Redial generations. Single-sporocyst infections were found in 69.3% (34/49) of infected snails, with equivalent numbers of normal and abnormal patterns. Snails with two- and three-sporocyst infections were 24.4% and 6.1%, respectively. In single- and two-sporocyst infections at days 42 and 56 post-exposure, the total Redial burden was significantly higher in snails with a normal Redial development. In two- and three-sporocyst infections, the overall maturity of Rediae was delayed at days 42 and 56. The high frequency of abnormal patterns in R. natalensis (53.1% of all infected snails showed degeneration of a first mother Redia) might be due to incomplete adaptation between the snail population and the parasite. The delayed Redial maturity in two- and three-sporocyst infections can mainly be explained by the volume of the snail body, which would be insufficient to allow the simultaneous differentiation of most Rediae over time.
-
Paramphistomum daubneyi: the number of sporocysts developing in experimentally and naturally infected Galba truncatula.
Parasitology Research Journal of Parasitology, 2008Co-Authors: G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out to determine at day 50 (at 24 degrees C) the numbers of sporocysts, which grew in infected snails via the count of first- and second-generation Rediae. In snails individually exposed to one, two, three, four, or five miracidia, the numbers of first-generation Rediae increased from the one-miracidium group to the five-miracidium snails (from a mean of 6.7 to 26.1), while second-generation Rediae decreased in number (from 6.2 to 0.9, respectively). This scale of Redial numbers was used to determine the number of sporocysts, which grew in naturally infected snails collected from sedimentary or acid soils between 1993 and 2006. In cercariae-containing snails, natural infections resulting from the development of one to five sporocysts were found in both samples of G. truncatula examined. The numbers of 3-, 4-, and 5-sporocyst infections were increasing over time since 1997, 2000, and 2003, respectively. The utility of such multiple-sporocyst infections is open to question, as the differentiation of second-generation Rediae and that of procercariae were delayed and always limited. They might be interpreted as a consequence of a zoonosis, which has been spreading since 1990 in ruminants of central France.
-
paramphistomum daubneyi the number of sporocysts developing in experimentally and naturally infected galba truncatula
Parasitology Research, 2008Co-Authors: G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out to determine at day 50 (at 24°C) the numbers of sporocysts, which grew in infected snails via the count of first- and second-generation Rediae. In snails individually exposed to one, two, three, four, or five miracidia, the numbers of first-generation Rediae increased from the one-miracidium group to the five-miracidium snails (from a mean of 6.7 to 26.1), while second-generation Rediae decreased in number (from 6.2 to 0.9, respectively). This scale of Redial numbers was used to determine the number of sporocysts, which grew in naturally infected snails collected from sedimentary or acid soils between 1993 and 2006. In cercariae-containing snails, natural infections resulting from the development of one to five sporocysts were found in both samples of G. truncatula examined. The numbers of 3-, 4-, and 5-sporocyst infections were increasing over time since 1997, 2000, and 2003, respectively. The utility of such multiple-sporocyst infections is open to question, as the differentiation of second-generation Rediae and that of procercariae were delayed and always limited. They might be interpreted as a consequence of a zoonosis, which has been spreading since 1990 in ruminants of central France.
-
Paramphistomum daubneyi: the number of sporocysts developing in experimentally and naturally infected Galba truncatula
Parasitology research, 2008Co-Authors: G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out to determine at day 50 (at 24°C) the numbers of sporocysts, which grew in infected snails via the count of first- and second-generation Rediae. In snails individually exposed to one, two, three, four, or five miracidia, the numbers of first-generation Rediae increased from the one-miracidium group to the five-miracidium snails (from a mean of 6.7 to 26.1), while second-generation Rediae decreased in number (from 6.2 to 0.9, respectively). This scale of Redial numbers was used to determine the number of sporocysts, which grew in naturally infected snails collected from sedimentary or acid soils between 1993 and 2006. In cercariae-containing snails, natural infections resulting from the development of one to five sporocysts were found in both samples of G. truncatula examined. The numbers of 3-, 4-, and 5-sporocyst infections were increasing over time since 1997, 2000, and 2003, respectively. The utility of such multiple-sporocyst infections is open to question, as the differentiation of second-generation Rediae and that of procercariae were delayed and always limited. They might be interpreted as a consequence of a zoonosis, which has been spreading since 1990 in ruminants of central France.
-
prevalence and intensity of infections in the lymnaeid snail omphiscola glabra experimentally infected with fasciola hepatica fascioloides magna and paramphistomum daubneyi
Journal of Helminthology, 2007Co-Authors: G Dreyfuss, Philippe Vignoles, A. Novobilský, V. Bellet, B. Koudela, D. RondelaudAbstract:Single and double infections of juvenile Omphiscola glabra (Gastropoda: Lymnaeidae) with Paramphistomum daubneyi and/or Fasciola hepatica were carried out to determine the Redial burden and cercarial production in snails dissected at day 60 or at day 75 post-exposure (p.e.) in the laboratory at 208C. The results were compared with those obtained with single-miracidium infections by Fascioloides magna. Compared to F. hepatica, low values were noted at day 75 p.e. for the prevalence of snail infections with P. daubneyi (4.6 – 8.3% instead of 23.6– 25.9%), the total number of free Rediae (10.7 – 17.9 per snail instead of 26.3– 34.7), and that of free cercariae (112.8– 136.9 per snail instead of 177.8 –248.5). Despite a greater number of free Rediae at day 75 p.e. (36.2 –45.6 per snail), the prevalences of snail infections with F. magna and cercarial production were similar to those noted for F. hepatica. The results concerning F. hepatica and P. daubneyi might partly be explained by a progressive adaptation of O. glabra to sustain the larval development of these digeneans over the years, as this snail is a natural intermediate host of F. hepatica and P. daubneyi in central France since 1995. Compared with the high number of fully-grown Rediae of F. magna in O. glabra, cercarial production seemed limited and this might be explained by the presence of high numbers of Rediae which reduced the avaibility of nutrients for cercarial differentiation within the snail.
Gilles Dreyfuss - One of the best experts on this subject based on the ideXlab platform.
-
Fasciola hepatica: the Redial generations in juvenile Pseudosuccinea columella
Parasitology research, 2015Co-Authors: Y. Dar, Daniel Rondelaud, Philippe Vignoles, Gilles DreyfussAbstract:Juvenile Pseudosuccinea columella, measuring 1 or 2 mm in height, were subjected to single-miracidium infections with Fasciola hepatica to determine the developmental pattern of Redial generations and count free and live Rediae according to their generation. Controls were constituted of juvenile Galba truncatula infected according to the same protocol. In the four groups, Redial counts were performed in snails dissected every week from day 7 to day 49 post-exposure at 20 °C. Most infected snails showed a normal development of Redial generations, whatever the lymnaeid species. In P. columella, the total number of live Rediae on day 49 was 24.6 and 34.6 per infected snail in the 1 and 2-mm groups, respectively (instead of 11.5 and 18.8 Rediae in the corresponding groups of G. truncatula). A single mother Redia (R1a) producing only daughter Rediae of the second generation was noted in each snail of three groups, while the 2-mm P. columella showed the presence of a single (43 snails/71) or two (28/71) R1a Redia(e) within their bodies. The mean number of other mother Rediae and that of daughter Rediae of the second generation were low in the 1 and 2-mm groups of both lymnaeids. Besides, there was a delay in Redial development. The development of two live R1a Rediae in several P. columella from the 2-mm group needs to verify if this process would be specific to P. columella or would occur in other lymnaeid species known for their good susceptibility to the digenean and their larger size to allow harbouring Rediae.
-
Growth rate of the intermediate snail host Galba truncatula influences Redial development of the trematode Fascioloides magna.
Journal of Helminthology, 2013Co-Authors: Daniel Rondelaud, Philippe Vignoles, A. Novobilský, J. Höglund, M. Kašný, J. Pankrác, Gilles DreyfussAbstract:A total of 850 pre-adult Galba truncatula (shell height, 4 mm), originating from four French snail populations differing in shell height at the adult stage (from 6.5 to 12 mm), were individually subjected at 20°C to single-miracidium infections with Fascioloides magna. At day 75 post-exposure, the surviving snails were dissected, and Rediae and cercariae were counted. Snail groups differed in shell growth during the experiment: from 1.8 ± 0.4 mm in group A up to 4.0 ± 1.1 mm in group D. The prevalence of F. magna infection, the numbers of free Rediae and cercariae significantly increased together with increasing growth of infected snails during the experiment. Group A produced 1-6 first-generation Rediae per snail and the mean daughter Redia production ranged from 7.5 second-generation Rediae (when a single first generation per snail developed) to 2.3 (6 first-generation Rediae per snail). In contrast, up to ten first-generation Rediae were noted in group D, and each mother Redia gave daughter Rediae with averages ranging from 1.5 (ten first-generation Rediae per snail) to 13 (a single first generation per snail). In conclusion, the development of F. magna in G. truncatula exhibited both inter- and intrapopulation variability, where the development of Rediae and cercariae was positively correlated with snail growth.
-
Redial generations of Fasciola hepatica: a review.
Journal of Helminthology, 2009Co-Authors: Daniel Rondelaud, Philippe Vignoles, M. Belfaiza, M. Moncef, Gilles DreyfussAbstract:An update on the Redial generations of Fasciola hepatica was carried out to highlight the different developmental patterns of Rediae, the effects of some factors on these generations, and the consequences of such developmental patterns on cercarial productivity. The development of generations is dependent on the behaviour of the first mother Redia of the first generation. If this Redia remains alive throughout snail infection, it produces most second-generation Rediae. In contrast, if it dies during the first weeks, daughter Redia formation is ensured by a substitute Redia (the second mother Redia of the first generation, or the first Redia of the second generation). Environmental and biotic factors do not modify the succession of Redial generations, but most act by limiting the numbers of Rediae, either in all generations, or in the second and/or third generations. An abnormal development of Rediae reduces the number of cercariae and most are formed by the second cohort of the first generation. By contrast, most cercariae are produced by the first cohort of the second generation when Redial development is normal. The mother Rediae described by previous authors might correspond to the first generation and the second cohort of the second generation, while daughter Rediae would be the second cohort of the second generation and the first cohort of the third generation. Under certain circumstances, daughter Redia formation is ensured by the first two mother Rediae or all first-generation Rediae, thus demonstrating that the first mother Redia is not the only larva to ensure daughter Redia formation.
-
Cercarial production of Fascioloides magna in the snail Galba truncatula (Gastropoda: Lymnaeidae).
Parasitology Research Journal of Parasitology, 2006Co-Authors: Philippe Vignoles, Daniel Rondelaud, A. Novobilský, V. Bellet, P. Treuil, B. Koudela, Gilles DreyfussAbstract:Single-miracidium infections of Fascioloides magna in two populations of Galba truncatula were carried out under laboratory conditions to count free Rediae and cercariae in snail cadavers just after death. Cercaria-shedding snails were in low numbers, and their shell height at day 60 p.e. was significantly greater than that of numerous infected snails that died without cercarial shedding. In snails that died between days 44 and 60 p.e. (at 20 degrees C), the numbers of second-generation Rediae significantly increased with increasing shell heights of infected snails. First-generation Rediae showed insignificant, quantitative variations, while scarce Rediae of the third generation were only found in the highest snails. Cercariae were only produced by the second Redial generation. In both groups of snails, free cercariae appeared from 6 mm of shell height, and their numbers increased in the upper classes up to 32.9 per snail. Metacercariae were only found from 9 mm of shell height and were in low numbers. The global cercarial production ranged from 163.5 to 210.0 in the highest classes of snail size from both groups and was limited, whereas the mean burdens of free Rediae fluctuated from 39.5 to 43.9. The death of numerous infected snails without cercarial shedding might be explained by the presence of a very high number of second-generation Rediae simultaneously growing within the body of these snails.
-
Fasciola hepatica: The growth and larval productivity of Redial generations in Galba truncatula subjected to miracidia differing in their mammalian origin
Journal of Parasitology, 2004Co-Authors: Philippe Vignoles, D. Rondelaud, A. Ménard, Albert Agoulon, Gilles DreyfussAbstract:Experimental infections of Galba truncatula with 4 isolates of Fasciola hepatica miracidia differing by their mammalian origin (cattle, nutrias, rabbits, or sheep) were carried out to determine if parasite origin had an effect on the number of free Rediae, their growth, and their larval productivity in each Redia category. The mammalian origin of miracidia had a significant influence on the numbers of free Rediae (they were higher in cattle-group snails) and the lengths of Rediae (they were lower in rabbit groups). The Redia category had also a significant effect on body and pharyngeal measurements. In all groups, the majority of cercariae (55.8–63.2%) were produced by the daughter Rediae (R2a Rediae) originating from the first mother Redia. Compared with the other groups, the mean number of cercariae at day 49 postexposure was twice as high in cattle groups. In contrast, the mean number of daughter Rediae produced by each second-appearing mother Redia or each R2a Redia was higher in the nutria, rabbit, and sheep groups. The mammalian origin of F. hepatica miracidia had an effect on the number of live Rediae, their length, and their Redial and cercarial productivity.
D. Rondelaud - One of the best experts on this subject based on the ideXlab platform.
-
prevalence and intensity of infections in the lymnaeid snail omphiscola glabra experimentally infected with fasciola hepatica fascioloides magna and paramphistomum daubneyi
Journal of Helminthology, 2007Co-Authors: G Dreyfuss, Philippe Vignoles, A. Novobilský, V. Bellet, B. Koudela, D. RondelaudAbstract:Single and double infections of juvenile Omphiscola glabra (Gastropoda: Lymnaeidae) with Paramphistomum daubneyi and/or Fasciola hepatica were carried out to determine the Redial burden and cercarial production in snails dissected at day 60 or at day 75 post-exposure (p.e.) in the laboratory at 208C. The results were compared with those obtained with single-miracidium infections by Fascioloides magna. Compared to F. hepatica, low values were noted at day 75 p.e. for the prevalence of snail infections with P. daubneyi (4.6 – 8.3% instead of 23.6– 25.9%), the total number of free Rediae (10.7 – 17.9 per snail instead of 26.3– 34.7), and that of free cercariae (112.8– 136.9 per snail instead of 177.8 –248.5). Despite a greater number of free Rediae at day 75 p.e. (36.2 –45.6 per snail), the prevalences of snail infections with F. magna and cercarial production were similar to those noted for F. hepatica. The results concerning F. hepatica and P. daubneyi might partly be explained by a progressive adaptation of O. glabra to sustain the larval development of these digeneans over the years, as this snail is a natural intermediate host of F. hepatica and P. daubneyi in central France since 1995. Compared with the high number of fully-grown Rediae of F. magna in O. glabra, cercarial production seemed limited and this might be explained by the presence of high numbers of Rediae which reduced the avaibility of nutrients for cercarial differentiation within the snail.
-
Fasciola hepatica: an unusual case of adaptation to a Moroccan population of Galba truncatula
Parasitology Research, 2005Co-Authors: M. Belfaiza, M. Moncef, D. RondelaudAbstract:Parent snails, F1, and F2, originating from a Moroccan population of Galba truncatula , were experimentally subjected to sympatric miracidia of Fasciola hepatica at 20°C to determine the mode of adaptation of this parasite to the local intermediate host via the study of Redial burdens and by following cercarial shedding. In spite of an increase in the global prevalences of infections, the frequencies recorded for immature or mature infections in dissected snails did not show any significant variations from parents to F2. If the Redial burdens in mature infections were mainly composed of first-generation Rediae in parent snails, the numbers of Rediae belonging to subsequent generations significantly increased in the F1 and F2 generations. In mature infections, the lengths of first-generation Rediae and their contents significantly decreased from parent snails to F2. Conversely, in the first Redial cohort of the second generation (R2a Rediae), only the intraRedial contents increased significantly with snail generation. In mature infections, daughter Redia production was ensured by all mother Rediae of the first generation in parent snails, whereas it was progressively effected by the first mother Redia in the F1 and F2 infections. The numbers of cercariae shed by snails increased significantly from parents to F2. If the cercariae produced by first-generation Rediae decreased with snail generation, an inverse finding was noted in the case of R2a Rediae. We suggest that snails impose a bottleneck on the development of the first mother Redia, so that other mother Rediae of the first generation react with greater growth (until 3.9 mm in parent snails), an important daughter Redia production and a high cercarial production. As the first mother Redia remained alive until day 49 post-exposure but without growth after week 2, this mode of development must be considered as a new developmental pattern of Redial generations, and it is useful to determine its frequency in snails, as it has never been found in naturally or experimentally infected snails in central France.
-
Fasciola hepatica: the developmental patterns of Redial generations in naturally infected Galba truncatula
Parasitology Research, 2004Co-Authors: D. Rondelaud, Philippe Vignoles, G DreyfussAbstract:A retrospective study on 1,211 snails naturally infected with Fasciola hepatica in central France was carried out to determine the numbers of full-grown sporocysts from which infections derived, to specify the developmental patterns of Redial generations (normal or abnormal) and to count live and free Rediae. In the department of Haute Vienne (siliceous subsoils), most snails showed single-sporocyst infections, with normal (46.3%) or abnormal (33.9%) development of Redial generations. Two-sporocyst infections were scarcer (a total of 10.6%), while snail co-infections with F. hepatica and Paramphistomum daubneyi (8.0%) were found since 1996. In the department of Indre (calcareous subsoils), single-sporocyst infections showing normal development of Rediae were the most numerous (58.0%), while the frequency of single-sporocyst infections with abnormal development was strongly decreased (4.3%). Two-sporocyst infections (with normal development of generations) and co-infections with F. hepatica and P. daubneyi slightly increased in frequency. The Redial burdens found in snails collected from the department of Indre were significantly higher than those noted in snails originating from the department of Haute Vienne, whatever the type of snail infection; and these increases in numbers especially concerned the Rediae of the second and subsequent generations. The results might be explained by the lower calcium ion content (7–23 mg/l) present in waters from the department of Haute Vienne which would induce a slower growth of infected snails (the shell height of adults scarcely reached 8 mm) and, consequently, would create barely favourable conditions for the development of the first Rediae of the first generation within snails. However, the quality of the diet provided as food for snails and its influence on the development of Redial generations cannot be excluded.
-
Fasciola hepatica: the effect of food quality on the development of Redial generations in Galba truncatula infected with allopatric miracidia
Parasitology Research, 2004Co-Authors: M. Belfaiza, M. Moncef, D. Rondelaud, G DreyfussAbstract:Individual bimiracidial infections of French Galba truncatula with an allopatric (Moroccan) isolate of Fasciola hepatica were carried out under laboratory conditions to count free Rediae and intraRedial daughter Rediae in snails just after their death, and to determine whether feeding the snails on lettuce only or lettuce plus Tetraphyll had an effect on the development of Redial generations. Controls consisted of snails infected with sympatric (French) miracidia and reared with lettuce only. In the allopatric group, reared with lettuce only as food, a higher mortality rate of snails in the first 4 weeks of the experiment was noted, and most G. truncatula showed 1-sporocyst infections, with the usual development of Redial generations. Compared to the sympatric group, the growth of the first mother Redia (R1a Redia) in each snail of the allopatric group was significantly slower during the first weeks of infection, whereas a significantly increased formation of intraRedial daughter Rediae in the other mother Rediae (R1b Rediae) was noted over the same period. In the allopatric group, reared with cos lettuce and commercial fish food, 1-sporocyst infections (45.5% of snails) and 2-sporocyst infections (53.9%), with the usual development of Redial generations, were noted. Compared to the sympatric group, a significantly slower development of the first mother Redia during the first weeks of the experiment was noted in the 1-sporocyst infections, whereas the values in the 2-sporocyst infections did not significantly differ from those noted in the sympatric group. Similar results were noted for the production of intraRedial daughter Rediae in the R1b Rediae during the first weeks of the experiment. In all infections derived from the growth of a single sporocyst per snail, the differentiation of numerous daughter Rediae inside R1b Rediae would be induced by the slow growth of the R1a Redia (from which the most important group of R2a Rediae originated) during the first weeks of infection and might represent a mechanism to replace free Rediae absent from the inside of the snail.
-
Fasciola hepatica: The growth and larval productivity of Redial generations in Galba truncatula subjected to miracidia differing in their mammalian origin
Journal of Parasitology, 2004Co-Authors: Philippe Vignoles, D. Rondelaud, A. Ménard, Albert Agoulon, Gilles DreyfussAbstract:Experimental infections of Galba truncatula with 4 isolates of Fasciola hepatica miracidia differing by their mammalian origin (cattle, nutrias, rabbits, or sheep) were carried out to determine if parasite origin had an effect on the number of free Rediae, their growth, and their larval productivity in each Redia category. The mammalian origin of miracidia had a significant influence on the numbers of free Rediae (they were higher in cattle-group snails) and the lengths of Rediae (they were lower in rabbit groups). The Redia category had also a significant effect on body and pharyngeal measurements. In all groups, the majority of cercariae (55.8–63.2%) were produced by the daughter Rediae (R2a Rediae) originating from the first mother Redia. Compared with the other groups, the mean number of cercariae at day 49 postexposure was twice as high in cattle groups. In contrast, the mean number of daughter Rediae produced by each second-appearing mother Redia or each R2a Redia was higher in the nutria, rabbit, and sheep groups. The mammalian origin of F. hepatica miracidia had an effect on the number of live Rediae, their length, and their Redial and cercarial productivity.
Philippe Vignoles - One of the best experts on this subject based on the ideXlab platform.
-
Fasciola hepatica: the Redial generations in juvenile Pseudosuccinea columella
Parasitology research, 2015Co-Authors: Y. Dar, Daniel Rondelaud, Philippe Vignoles, Gilles DreyfussAbstract:Juvenile Pseudosuccinea columella, measuring 1 or 2 mm in height, were subjected to single-miracidium infections with Fasciola hepatica to determine the developmental pattern of Redial generations and count free and live Rediae according to their generation. Controls were constituted of juvenile Galba truncatula infected according to the same protocol. In the four groups, Redial counts were performed in snails dissected every week from day 7 to day 49 post-exposure at 20 °C. Most infected snails showed a normal development of Redial generations, whatever the lymnaeid species. In P. columella, the total number of live Rediae on day 49 was 24.6 and 34.6 per infected snail in the 1 and 2-mm groups, respectively (instead of 11.5 and 18.8 Rediae in the corresponding groups of G. truncatula). A single mother Redia (R1a) producing only daughter Rediae of the second generation was noted in each snail of three groups, while the 2-mm P. columella showed the presence of a single (43 snails/71) or two (28/71) R1a Redia(e) within their bodies. The mean number of other mother Rediae and that of daughter Rediae of the second generation were low in the 1 and 2-mm groups of both lymnaeids. Besides, there was a delay in Redial development. The development of two live R1a Rediae in several P. columella from the 2-mm group needs to verify if this process would be specific to P. columella or would occur in other lymnaeid species known for their good susceptibility to the digenean and their larger size to allow harbouring Rediae.
-
Growth rate of the intermediate snail host Galba truncatula influences Redial development of the trematode Fascioloides magna.
Journal of Helminthology, 2013Co-Authors: Daniel Rondelaud, Philippe Vignoles, A. Novobilský, J. Höglund, M. Kašný, J. Pankrác, Gilles DreyfussAbstract:A total of 850 pre-adult Galba truncatula (shell height, 4 mm), originating from four French snail populations differing in shell height at the adult stage (from 6.5 to 12 mm), were individually subjected at 20°C to single-miracidium infections with Fascioloides magna. At day 75 post-exposure, the surviving snails were dissected, and Rediae and cercariae were counted. Snail groups differed in shell growth during the experiment: from 1.8 ± 0.4 mm in group A up to 4.0 ± 1.1 mm in group D. The prevalence of F. magna infection, the numbers of free Rediae and cercariae significantly increased together with increasing growth of infected snails during the experiment. Group A produced 1-6 first-generation Rediae per snail and the mean daughter Redia production ranged from 7.5 second-generation Rediae (when a single first generation per snail developed) to 2.3 (6 first-generation Rediae per snail). In contrast, up to ten first-generation Rediae were noted in group D, and each mother Redia gave daughter Rediae with averages ranging from 1.5 (ten first-generation Rediae per snail) to 13 (a single first generation per snail). In conclusion, the development of F. magna in G. truncatula exhibited both inter- and intrapopulation variability, where the development of Rediae and cercariae was positively correlated with snail growth.
-
The development of Rediae of Fasciola hepatica in Radix natalensis subjected twice to bimiracidial exposures.
Journal of Helminthology, 2010Co-Authors: Y. Dar, G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Egyptian Radix natalensis with a French isolate of Fasciola hepatica (each snail was subjected twice to a bimiracidial exposure) were carried out to determine how many sporocysts grew in these snails and to study the developmental patterns of Redial generations. Single-sporocyst infections were found in 69.3% (34/49) of infected snails, with equivalent numbers of normal and abnormal patterns. Snails with two- and three-sporocyst infections were 24.4% and 6.1%, respectively. In single- and two-sporocyst infections at days 42 and 56 post-exposure, the total Redial burden was significantly higher in snails with a normal Redial development. In two- and three-sporocyst infections, the overall maturity of Rediae was delayed at days 42 and 56. The high frequency of abnormal patterns in R. natalensis (53.1% of all infected snails showed degeneration of a first mother Redia) might be due to incomplete adaptation between the snail population and the parasite. The delayed Redial maturity in two- and three-sporocyst infections can mainly be explained by the volume of the snail body, which would be insufficient to allow the simultaneous differentiation of most Rediae over time.
-
Redial generations of Fasciola hepatica: a review.
Journal of Helminthology, 2009Co-Authors: Daniel Rondelaud, Philippe Vignoles, M. Belfaiza, M. Moncef, Gilles DreyfussAbstract:An update on the Redial generations of Fasciola hepatica was carried out to highlight the different developmental patterns of Rediae, the effects of some factors on these generations, and the consequences of such developmental patterns on cercarial productivity. The development of generations is dependent on the behaviour of the first mother Redia of the first generation. If this Redia remains alive throughout snail infection, it produces most second-generation Rediae. In contrast, if it dies during the first weeks, daughter Redia formation is ensured by a substitute Redia (the second mother Redia of the first generation, or the first Redia of the second generation). Environmental and biotic factors do not modify the succession of Redial generations, but most act by limiting the numbers of Rediae, either in all generations, or in the second and/or third generations. An abnormal development of Rediae reduces the number of cercariae and most are formed by the second cohort of the first generation. By contrast, most cercariae are produced by the first cohort of the second generation when Redial development is normal. The mother Rediae described by previous authors might correspond to the first generation and the second cohort of the second generation, while daughter Rediae would be the second cohort of the second generation and the first cohort of the third generation. Under certain circumstances, daughter Redia formation is ensured by the first two mother Rediae or all first-generation Rediae, thus demonstrating that the first mother Redia is not the only larva to ensure daughter Redia formation.
-
Paramphistomum daubneyi: the number of sporocysts developing in experimentally and naturally infected Galba truncatula.
Parasitology Research Journal of Parasitology, 2008Co-Authors: G Dreyfuss, Philippe Vignoles, Daniel RondelaudAbstract:Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out to determine at day 50 (at 24 degrees C) the numbers of sporocysts, which grew in infected snails via the count of first- and second-generation Rediae. In snails individually exposed to one, two, three, four, or five miracidia, the numbers of first-generation Rediae increased from the one-miracidium group to the five-miracidium snails (from a mean of 6.7 to 26.1), while second-generation Rediae decreased in number (from 6.2 to 0.9, respectively). This scale of Redial numbers was used to determine the number of sporocysts, which grew in naturally infected snails collected from sedimentary or acid soils between 1993 and 2006. In cercariae-containing snails, natural infections resulting from the development of one to five sporocysts were found in both samples of G. truncatula examined. The numbers of 3-, 4-, and 5-sporocyst infections were increasing over time since 1997, 2000, and 2003, respectively. The utility of such multiple-sporocyst infections is open to question, as the differentiation of second-generation Rediae and that of procercariae were delayed and always limited. They might be interpreted as a consequence of a zoonosis, which has been spreading since 1990 in ruminants of central France.