Fasciola hepatica larval development within the intermediate host.

2021 ◽  
pp. 23-64
Author(s):  
Gilles Dreyfuss ◽  
Philippe Sindou ◽  
Philippe Hourdin ◽  
Philippe Vignoles ◽  
Daniel Rondelaud

Abstract This book chapter focuses on host snail species and larval behavior forms in snails, and features of parasitic infections in naturally or experimentally infected snails, or in coinfected snails.

Author(s):  
D.M. Pfukenyi ◽  
Pfukenyi Mukaratirwa ◽  
A.L. Willingham ◽  
J. Monrad

During the period between January 1999 and December 2000, the distribution and seasonal patterns of Fasciola gigantica infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe were determined through monthly coprological examination. Cattle faecal samples were collected from 12 and nine dipping sites in the highveld and lowveld communal grazing areas respectively. Patterns of distribution and seasonal fluctuations of the intermediate host-snail populations and the climatic factors influencing the distribution were also determined by sampling at monthly intervals for a period of 24 months (November 1998 to October 2000) in six dams and six streams in the highveld and in nine dams in the lowveld communal grazing areas. Each site was sampled for relative snail density and the vegetation cover and type, physical and chemical properties of water, and mean monthly rainfall and temperature were recorded. Aquatic vegetation and grass samples 0-1 m from the edges of the snail habitats were collected monthly to determine the presence or absence of F. gigantica metacercariae. Snails collected at the same time were individually checked for the emergence of larval stages of F. gigantica. A total of 16 264 (calves 5 418; weaners 5 461 and adults 5 385) faecal samples were collected during the entire period of the study and 2 500 (15.4 %) of the samples were positive for F. gigantica eggs. Significantly higher prevalences were found in the highveld compared to the lowveld (P < 0.001), for adult cattle than calves ( P < 0.01) and in the wet season over the dry season (P < 0.01). Faecal egg output peaked from August / September to March / April for both years of the study. Lymnaea natalensis, the snail intermediate host of F. gigantica was recorded from the study sites with the highveld having a significantly higher abundance of the snail species than the lowveld (P < 0.01). The snail population was low between December and March and started to increase in April reaching a peak in September / October. The number of juvenile snails peaked between April and August. The mean number of snails collected was negatively correlated with rainfall and positively correlated with temperature. Mean number of snails collected was also positively correlated with Potamogeton plant species and negatively correlated with Cyperus plant species. However, none of the L. natalensis collected from the habitats were found shedding Fasciola cercariae. Metacercariae were found on herbage from the fringes of the snail habitats between February and August for both years, with most of the metacercariae concentrated on herbage 0-1 m from the banks of the habitats. Based on the findings of this study, anthelmintic treatment should be administered in December / January to control chronic and mature fasciolosis. A second treatment should be given in April / May to reduce pasture contamination and subsequently snail infection, as this is the time the snail population starts to build up. To control acute fasciolosis due to the immature liver flukes a third treatment should be given in August. The first application of molluscicides to control the snail intermediate hosts can be done in June the time when the snail is harbouring the parasite and a second application in September in order to kill new generations of infected snails.


2014 ◽  
Vol 89 (6) ◽  
pp. 699-706 ◽  
Author(s):  
Y. Dar ◽  
P. Vignoles ◽  
D. Rondelaud ◽  
G. Dreyfuss

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.


2007 ◽  
Vol 81 (1) ◽  
pp. 7-12 ◽  
Author(s):  
G. Dreyfuss ◽  
A. Novobilský ◽  
P. Vignoles ◽  
V. Bellet ◽  
B. Koudela ◽  
...  

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.


2020 ◽  
pp. 1616
Author(s):  
Manuel Antonio Lepe López ◽  
Ederico Villatoro-Paz ◽  
Juan Carlos Valdez Sandoval ◽  
Ligia Vanessa Rios ◽  
Mercedes Diaz Rodríguez ◽  
...  

Objective. Identify the natural infection of freshwater snails as an intermediate host of Fasciola hepatica in Guatemala. Materials and methods. Freshwater snails were collected in a high-altitude village (3.000 mamsl) from Huehuetenango department, where fasciolasis is endemic. The identification of the snail species was based on the morphological characteristics observed under the stereoscope using an identification key. The trematode phases were searched externally by visual inspection using a light source, and internally by dissection and visual inspection of the tissues under a stereoscope and microscope. Results. 260 snails were found and identified as Pseudosuccinea columella. Two of them were found naturally infected with larval phases of F. hepatica. Conclusions. This is the first report of P. columella carrying phases of F. hepatica in the highlands of Guatemala. It is necessary to increase the research of the ecology of this parasite in other understudied areas in Guatemala and Central America, due to the latent risk of infection for populations of herbivorous animals and humans.


Parasitology ◽  
2009 ◽  
Vol 136 (13) ◽  
pp. 1683-1693 ◽  
Author(s):  
C. Simoonga ◽  
J. Utzinger ◽  
S. Brooker ◽  
P. Vounatsou ◽  
C. C. Appleton ◽  
...  

SUMMARYBeginning in 1970, the potential of remote sensing (RS) techniques, coupled with geographical information systems (GIS), to improve our understanding of the epidemiology and control of schistosomiasis in Africa, has steadily grown. In our current review, working definitions of RS, GIS and spatial analysis are given, and applications made to date with RS and GIS for the epidemiology and ecology of schistosomiasis in Africa are summarised. Progress has been made in mapping the prevalence of infection in humans and the distribution of intermediate host snails. More recently, Bayesian geostatistical modelling approaches have been utilized for predicting the prevalence and intensity of infection at different scales. However, a number of challenges remain; hence new research is needed to overcome these limitations. First, greater spatial and temporal resolution seems important to improve risk mapping and understanding of transmission dynamics at the local scale. Second, more realistic risk profiling can be achieved by taking into account information on people's socio-economic status; furthermore, future efforts should incorporate data on domestic access to clean water and adequate sanitation, as well as behavioural and educational issues. Third, high-quality data on intermediate host snail distribution should facilitate validation of infection risk maps and modelling transmission dynamics. Finally, more emphasis should be placed on risk mapping and prediction of multiple species parasitic infections in an effort to integrate disease risk mapping and to enhance the cost-effectiveness of their control.


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