Larval development of Fasciola hepatica in experimental infections: variations with populations of Lymnaea truncatula

2002 ◽  
Vol 76 (2) ◽  
pp. 179-183 ◽  
Author(s):  
P. Vignoles ◽  
G. Dreyfuss ◽  
D. Rondelaud
Keyword(s):  
Retrospective Study ◽  
Genetic Variability ◽  
Larval Development ◽  
Experimental Infection ◽  
Fasciola Hepatica ◽  
The Other ◽  
Mammalian Host ◽  
Cercarial Production ◽  
Lymnaea Truncatula ◽  
Low Prevalence

AbstractA retrospective study was undertaken on 70 French populations of Lymnaea truncatula experimentally infected with Fasciola hepatica to determine whether or not susceptibility of snails to infection influenced redial and cercarial production. Results were compared with those obtained from two control populations, known for prevalences higher than 60% when experimentally infected with F. hepatica. In the 70 other populations examined, the prevalences ranged from 2 to 75%. In 55 of these populations, where the prevalence was more than 20%, a high proportion (50.1–56.8%) of snails died after cercarial shedding, whereas in the other groups (non-shedding snails with the most differentiated larvae being free cercariae, rediae containing cercariae, immature rediae, or sporocysts, respectively), snail death was significantly less. In 11 populations, where the prevalence values were 5–19%, only 14% of snails died after cercarial shedding, whereas snails with free cercariae, rediae with cercariae, or immature rediae showed significant increases in snail mortality. In the remaining four snail populations, with prevalences of less than 5%, the most differentiated larval forms were only immature rediae and/or sporocysts. Overall, the number of rediae containing cercariae significantly decreased with decreasing prevalence values. The low prevalence of experimental infection in several populations of snails might be explained by the occurrence of natural infections with miracidia originating from a mammalian host other than cattle, and/or by genetic variability in the susceptibility of snails to infection.

Cercarial productivity of redial generations in single-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or Fasciola hepatica

2000 ◽  
Vol 74 (1) ◽  
pp. 1-5 ◽  
Author(s):  
M. Abrous ◽  
D. Rondelaud ◽  
G. Dreyfuss
Keyword(s):  
Fasciola Hepatica ◽  
The Other ◽  
Redial Generation ◽  
Post Exposure ◽  
Laboratory Conditions ◽  
Lymnaea Truncatula

AbstractSingle-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or with Fasciola hepatica were carried out under laboratory conditions to count free rediae, their germinal embryos, and to determine the cercarial productivity of each redial generation. In snails infected by P. daubneyi, the cercariae were produced by the first (8.7 cercariae per redia) and second (8.9 per redia) generations. At day 63 post-exposure, they corresponded, respectively, to 53.9% and 46.1% of cercariae produced by all rediae. In snails infected by F. hepatica, the majority of cercariae were produced by the R2a group (18.2 cercariae per redia) and corresponded to 66.0% of cercariae produced all rediae. The cercariae produced by the other redial groups were more limited in number: 17.5 per redia in the R1b group (28.7%) and 2.0 per redia in the R2b/R3a group (5.3%). Cercarial productivity of P. daubneyi until day 63 post-exposure was more limited in number than that of F. hepatica: a total of 145 cercariae per snail versus 427 per snail.

Role of the lymnaeid snailPseudosuccinea columellain the transmission of the liver flukeFasciola hepaticain Egypt

2014 ◽  
Vol 89 (6) ◽  
pp. 699-706 ◽  
Author(s):  
Y. Dar ◽  
P. Vignoles ◽  
D. Rondelaud ◽  
G. Dreyfuss
Keyword(s):  
Microsatellite Markers ◽  
Intermediate Host ◽  
Larval Development ◽  
Experimental Infection ◽  
Fasciola Hepatica ◽  
Experimental Infections ◽  
Lymnaeid Snail ◽  
Important Intermediate

AbstractExperimental infections of three EgyptianPseudosuccinea columellapopulations with sympatric miracidia ofFasciolasp., coming from cattle- or sheep-collected eggs, were carried out to determine the capacity of this lymnaeid to support larval development of the parasite. Using microsatellite markers, the isolates of Egyptian miracidia were identified asFasciola hepatica. Apart from being independent of snail origin, prevalences ranging from 60.4 to 75.5% in snails infected with five miracidia ofF. hepaticawere significantly higher than values of 30.4 to 42.2% in snails with bi-miracidial infections. The number of metacercariae ranged from 243 to 472 per cercarial-shedding snail and was independent of snail origin, parasite origin and miracidial dose used for infection. IfP. columellawas subjected to two successive bi-miracidial infections withF. hepatica, prevalence of infection was 63.3%, with a mean of 311 metacercariae per snail. These values were clearly greater than those already reported forRadix natalensisinfected with the same parasite and the same protocol. Successful experimental infection ofP. columellawithF. hepaticasuggests that this lymnaeid snail is an important intermediate host for the transmission of fascioliasis in Egypt.

The stimulation of daughter redia production during the larval development of Fasciola hepatica

Parasitology ◽  
1976 ◽  
Vol 72 (3) ◽  
pp. 245-257 ◽  
Author(s):  
R. A. Wilson ◽  
Tove Draskau
Keyword(s):  
High Temperature ◽  
Larval Development ◽  
Fasciola Hepatica ◽  
Snail Host ◽  
Parasite Development ◽  
Cercarial Production ◽  
Stimulation Of

SummaryIn snails maintained at 20 °C rediae of Fasciola hepatica emerge from sporocysts from 11 days after infection onwards. The number of mother rediae rises steadily thereafter until at least 40 days after infection. Daughter rediae are seldom observed in mother rediae dissected from snails maintained at 20 °C. Their production can, however, be stimulated by subjecting the snail host to starvation, to low, and to high temperature shocks. The parasite is susceptible to stress from immediately after infection for about 16 days, when maintained at 20 °C. In general, the more extreme the shock, the greater is daughter redial production. Increasing the length of the period of stress from 12 h up to 9 days does not increase the production of daughter rediae, nor does repeated on/off cold shocks or continuous maintenance at 10 °C. Daughter rediae develop more rapidly than cercariae and leave the mother rediae several days earlier. There is no evidence that presence of daughter rediae coincides with the suppression of cercarial production. The findings are discussed with reference to possible mechanisms by which parasite development might be controlled.

Fasciola hepatica: the infection rate and the development of redial generations in Lymnaea truncatula exposed to miracidia after experimental desiccation and activation in water

1994 ◽  
Vol 68 (1) ◽  
pp. 63-66 ◽  
Author(s):  
D. Rondelaud
Keyword(s):  
Infection Rate ◽  
First Generation ◽  
Second Generation ◽  
Fasciola Hepatica ◽  
The Other ◽  
Lymnaea Truncatula

AbstractAdult Lymnaea truncatula were subjected to 10 days of experimental desiccation and then remained in water for 1 or 8 days before each was exposed to a single miracidium. The infection rate was lower in these snails than in infected controls that were not exposed to stress (52–54% vs 73%). The redial burden clearly decreased in stressed snails (18–25 rediae per snail) than in controls (43 rediae). This numerical decrease concerned essentially: i) live independent rediae of the first generation and the first cohort of the second generation, and ii) dependent rediae of subsequent generations. Mature rediae were more numerous in the first cohort of the second generation than in the other generations. Desiccation before exposure limited the size of the redial burden but placement in water for 8 days just after the stress attenuated the effects of this factor.

Prevalence and intensity of infections in the lymnaeid snail Omphiscola glabra experimentally infected with Fasciola hepatica, Fascioloides magna and Paramphistomum daubneyi

2007 ◽  
Vol 81 (1) ◽  
pp. 7-12 ◽  
Author(s):  
G. Dreyfuss ◽  
A. Novobilský ◽  
P. Vignoles ◽  
V. Bellet ◽  
B. Koudela ◽  
...  
Keyword(s):  
Intermediate Host ◽  
Larval Development ◽  
Fasciola Hepatica ◽  
Fascioloides Magna ◽  
Post Exposure ◽  
Cercarial Production ◽  
Lymnaeid Snail

AbstractSingle 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 20°C. 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.

The presence of predators modifies the larval development of Fasciola hepatica in surviving Lymnaea truncatula

2002 ◽  
Vol 76 (2) ◽  
pp. 175-178 ◽  
Author(s):  
D. Rondelaud ◽  
P. Vignoles ◽  
G. Dreyfuss
Keyword(s):  
Survival Rate ◽  
Larval Development ◽  
Significant Variation ◽  
Fasciola Hepatica ◽  
Stress Reaction ◽  
Experimental Exposure ◽  
Post Exposure ◽  
Progressive Development ◽  
Experimental Infections ◽  
Lymnaea Truncatula

AbstractExperimental infections of Lymnaea truncatula with Fasciola hepatica were performed to study the consequences of the presence of predators (sciomyzid larvae or zonitid snails) on the characteristics of larval F. hepatica development in surviving snails. Controls consisted of infected snails that were not subjected to predators. Compared to controls, the survival rate at day 30 post-exposure, the duration of cercarial shedding, and the number of cercariae shed by surviving snails were significantly lower when predators were present in snail breeding boxes, whatever the type of predator used. In contrast, the prevalences of Fasciola infections in snails, and the length of time between exposure and the onset of cercarial shedding showed no significant variation. The progressive development of a stress reaction in surviving snails against predators during the first 30 days of experimental exposure to F. hepatica would influence snail survival during the cercarial shedding period and, consequently, the number of cercariae shed by the snails.

Variability of Fasciola infections in Lymnaea truncatula as a function of snail generation and snail activity

1997 ◽  
Vol 71 (2) ◽  
pp. 161-166 ◽  
Author(s):  
D. Rondelaud ◽  
G. Dreyfuss
Keyword(s):  
Fasciola Hepatica ◽  
Prepatent Period ◽  
The Other ◽  
Infection Rates ◽  
Patent Period ◽  
Summer Generation ◽  
Experimental Infections ◽  
Field Investigations ◽  
Lymnaea Truncatula

AbstractField investigations were carried out over a 4-year period in three farms of the Haute-Vienne department (France) in order to determine the prevalence of Fasciola hepatica infection in the annual generations of Lymnaea truncatula. Infection rates found in March were significantly lower than those recorded in July or in September (0.8% to 2.2% compared to 5.7% to 13.5% and 4.4% to 9.3%, respectively). They were always lower in overwintering snails than in other snail generations (summer generation in 1989,1990 and 1991; spring and summer generations in 1992). Experimental infections of L. truncatula by F. hepatica were performed to evaluate the characteristics of Fasciola infection with reference to snail generation and snail activity. Survival of summer generation snails at day 30 postexposure was significantly lower in snails collected in September than in those collected in May and June. In the winter generation of L. truncatula, snail survival was significantly higher in snails collected from December to March than in those from November. The prevalence of infection was significantly lower in snails collected in September (summer generation) than in those collected from December to March (winter generation). The duration of the prepatent period was significantly delayed in snails collected from January to March (a mean of 54.2 to 58.2 days instead of 43.1 to 49 days in the other groups), whereas that of the patent period was significantly shorter (5 to 9.3 days instead of 18.3 to 40.3 days, respectively). In snails collected from January to March, the number of metacercariae was significantly lower than that found from other snail groups (a mean of 21.5 to 42 metacercariae instead of 72.8 to 151.4 cysts, respectively). Fasciola infections of L. truncatula originating from spring and summer generations were more efficient than those from the winter generation of snails.

Fasciola hepatica: an unusual development of redial generations in an isolate of Lymnaea truncatula

1999 ◽  
Vol 73 (1) ◽  
pp. 27-30 ◽  
Author(s):  
D. Augot ◽  
M. Abrous ◽  
D. Rondelaud ◽  
G. Dreyfuss ◽  
J. Cabaret
Keyword(s):  
Larval Development ◽  
Fasciola Hepatica ◽  
The Body ◽  
Pharyngeal Wall ◽  
Post Exposure ◽  
Pharyngeal Region ◽  
Lymnaea Truncatula

Single-miracidium infections of Lymnaea truncatula by Fasciola hepatica were experimentally carried out to identify the redial generations of this trematode when the larval development was unusual (when the first-appearing mother redia, or R1a redia, died after its exit from the sporocyst). Four parameters were measured in the body and pharyngeal region at weekly intervals. At day 49 post-exposure at 20°C, the body of the second mother rediae (R1b) was significantly longer than that of the subsequent generations, R2a and R2b/R3a (a mean of 3.0 mm instead of 1.0 and 0.9 mm, respectively). The body was significantly wider in the R1b and R2a groups than in the R2b/R3a rediae. The pharyngeal lumen was significantly wider in the R1b group than in the R2a and R2b/R3a rediae (a mean of 48.6 μm instead of 10.8 and 3.3 μm at day 49). The thickness of the pharyngeal wall did not differ in the R1b and R2b/R3a groups, but was significantly lower in the R2a group (19.5 μm instead of 23.0–23.6 at day 49). There was better development of R1b and R2b/R3a rediae in the snails when the R1a redia died, compared with normal larval development (with a living R1a redia).

Calicophoron daubneyiandFasciola hepatica: characteristics of natural and experimental co-infections of these digeneans in the snailLymnaea glabra

2016 ◽  
Vol 91 (1) ◽  
pp. 1-6 ◽  
Author(s):  
P. Vignoles ◽  
A. Titi ◽  
A. Mekroud ◽  
D. Rondelaud ◽  
G. Dreyfuss
Keyword(s):  
Retrospective Study ◽  
Fasciola Hepatica ◽  
Shell Height ◽  
The Other ◽  
Patent Period ◽  
Galba Truncatula ◽  
Experimental Infections ◽  
Calicophoron Daubneyi

AbstractA retrospective study on differentLymnaea glabrasamples collected from central France between 1993 and 2010 was carried out to determine the prevalence of natural co-infections withCalicophoron daubneyiandFasciola hepatica, and to specify the composition of redial burdens. Experimental infections ofL. glabraperformed during the same period of time were also analysed to study metacercarial production of each digenean in co-infected snails. Controls were naturally or experimentally co-infectedGalba truncatula. In natural co-infections, prevalence was 0.7% inL. glabra(186/25,128) and 0.4% inG. truncatula(137/31,345). Low redial burdens were found in these snails, withF. hepaticarediae significantly more numerous inL. glabrathan inG. truncatula(7.5 per snail instead of 5.2). In contrast, the total numbers ofC. daubneyirediae in both lymnaeids were close to each other (4.3 and 3.0 rediae, respectively). In experimentally co-infected groups, prevalence was greater inG. truncatulathan in the other lymnaeid (6.3% instead of 3.0%). Significantly shorter patent periods and lower metacercarial production for each digenean were noted inL. glabrathan inG. truncatula.However, in both lymnaeids, the two types of cercariae were released during the same shedding waves and several peaks during the patent period were synchronous. In spite of a greater shell height forL. glabra, metacercarial production of both digeneans in co-infected snails was lower than that inG. truncatula, thus indicating a still incomplete adaptation between these FrenchL. glabraand both parasites.

scholarly journals Relationship between Cycling Infrastructure and Transportation Cycling in a Small Urban Area

2021 ◽  
Vol 1 (1) ◽  
pp. 99-112
Author(s):  
Richard Larouche ◽  
Nimesh Patel ◽  
Jennifer L. Copeland
Keyword(s):  
Generalized Linear Models ◽  
Qualitative Data ◽  
Linear Models ◽  
The Other ◽  
Small City ◽  
The Road ◽  
The Past ◽  
Low Prevalence ◽  
The Relationship

The role of infrastructure in encouraging transportation cycling in smaller cities with a low prevalence of cycling remains unclear. To investigate the relationship between the presence of infrastructure and transportation cycling in a small city (Lethbridge, AB, Canada), we interviewed 246 adults along a recently-constructed bicycle boulevard and two comparison streets with no recent changes in cycling infrastructure. One comparison street had a separate multi-use path and the other had no cycling infrastructure. Questions addressed time spent cycling in the past week and 2 years prior and potential socio-demographic and psychosocial correlates of cycling, including safety concerns. Finally, we asked participants what could be done to make cycling safer and more attractive. We examined predictors of cycling using gender-stratified generalized linear models. Women interviewed along the street with a separate path reported cycling more than women on the other streets. A more favorable attitude towards cycling and greater habit strength were associated with more cycling in both men and women. Qualitative data revealed generally positive views about the bicycle boulevard, a need for education about sharing the road and for better cycling infrastructure in general. Our results suggest that, even in smaller cities, cycling infrastructure may encourage cycling, especially among women.

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