Seasonal occurrence of Cyathocotyle bushiensis Khan, 1962 (Digenea: Cyathocotylidae) metacercariae in the intermediate host Bithynia tentaculata L. (Gastropoda: Prosobranchia)

1987 ◽  
Vol 65 (12) ◽  
pp. 2980-2992 ◽  
Author(s):  
L. Ménard ◽  
M. E. Scott
Keyword(s):  
Intermediate Host ◽  
Late Summer ◽  
Snail Population ◽  
Close Link ◽  
Transmission Rates ◽  
Total Prevalence ◽  
Bithynia Tentaculata ◽  
Population Comparison ◽  
Infected Area ◽  
Cyathocotyle Bushiensis

Cyathocotyle bushiensis Khan, 1962 (Digenea) has been associated with late-summer duck mortality in southern Quebec. In an attempt to relate these die-offs with seasonal availability of the infective metacercariae to the ducks, two intermediate host (Bithynia tentaculata L.) populations were regularly sampled in 1984 and 1985. Prevalence varied between 5.3 and 57.3% at the South River, and between 9.1 and 49.7% at Lake St. Francis over the period of the study. Maximum abundances at the two localities were 1.38 and 1.66 metacercariae per snail, respectively. No close link between availability of metacercariae and periods of duck mortality was found, as the total prevalence and abundance of the cysts decreased through the summer, probably as a consequence of snail recruitment and low cercarial transmission rates, and increased in the autumn. Prevalence and abundance of metacercariae increased with snail age, estimated by both size and annual growth lines, and the metacercariae were found to be aggregated in the snail population. Comparison of infection levels reached at the end of the two sampling seasons by two year classes of B. tentaculata suggested that transmission of cercariae was higher in 1984 than in 1985. This was supported by the results of exposure of sentinel snails in an infected area during the 2 years of the study: transmission was detected in 1984 but not in 1985. In addition to C. bushiensis metacercariae, the sentinel snails acquired Sphaeridiotrema globulus (Rudolphi, 1814), another potential duck pathogen, in both years. The peak rate of transmission of S. globulus metacercariae occurred in August.

Spatial and temporal structure of the trematode component community inValvata macrostoma(Gastropoda, Prosobranchia)

Parasitology ◽  
2008 ◽  
Vol 135 (14) ◽  
pp. 1691-1699 ◽  
Author(s):  
A. FALTÝNKOVÁ ◽  
E. T. VALTONEN ◽  
A. KARVONEN
Keyword(s):  
Temporal Structure ◽  
Trematode Species ◽  
Snail Population ◽  
Community Studies ◽  
Component Community ◽  
Spatial And Temporal Scales ◽  
Total Prevalence ◽  
Ca 50 ◽  
Parasite Dynamics ◽  
Comprehensive Study

SUMMARYWe conducted the first comprehensive study on the spatiotemporal structure of trematode communities in the large-mouthed valve snail,Valvata macrostoma. A total of 1103 snails were examined monthly between May and October 2007 from Lake Konnevesi, Central Finland, from a shallow (1–2 m deep) and an offshore site (5–6 m deep), located ca. 50–70 m apart. Snails were infected by 10 trematode species. The species composition and prevalence were strikingly different between the sites with high species diversity in the shallow site (all 10 species; total prevalence of sporocysts/rediae 12·1%, metacercariae 55·4%) compared to the deeper site (3 species; prevalence 15·0% and 1·9%, respectively). This difference persisted throughout our study and is probably related to the spatial distribution of bird definitive hosts, whereas the seasonal parasite dynamics are likely to be affected by changes in the age-structure of the snail population. The probability of sporocyst infections increased with snail size, but no such trend was observed in redial or metacercarial infections which decreased with host size. Our results show that generally well-described spatiotemporal differences in trematode infection of molluscs can emerge in very narrow spatial and temporal scales, which emphasizes the importance of these factors in community studies.

scholarly journals Epidemiological studies of Fasciola gigantica infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe

2006 ◽  
Vol 73 (1) ◽  
Author(s):  
D.M. Pfukenyi ◽  
Pfukenyi Mukaratirwa ◽  
A.L. Willingham ◽  
J. Monrad
Keyword(s):  
Intermediate Host ◽  
Plant Species ◽  
Aquatic Vegetation ◽  
Climatic Factors ◽  
Fasciola Gigantica ◽  
Snail Species ◽  
Snail Population ◽  
Adult Cattle ◽  
Host Snail ◽  
Faecal Samples

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.

scholarly journals Schistosoma transmission in a dynamic seasonal environment and its impact on the effectiveness of disease control

2020 ◽  
Author(s):  
Qimin Huang ◽  
David Gurarie ◽  
Martial Ndeffo-Mbah ◽  
Emily Li ◽  
Charles H King
Keyword(s):  
Seasonal Variation ◽  
Intermediate Host ◽  
Control Strategies ◽  
Control Measures ◽  
Seasonal Effects ◽  
Effective Control ◽  
Optimal Timing ◽  
Snail Population ◽  
Dynamics And Control ◽  
The Impact

Abstract Background A seasonal transmission environment including seasonal variation of snail population density and human-snail contact patterns can affect the dynamics of Schistosoma infection and the success of control interventions. In projecting control outcomes, conventional modeling approaches have often ignored seasonality by using simplified intermediate-host modeling, or by restricting seasonal effects through use of yearly averaging. Methods We used mathematical analysis and numerical simulation to estimate the impact of seasonality on disease dynamics and control outcomes, and to evaluate whether seasonal averaging or intermediate-host reduction can provide reliable predictions of control outcomes. We also examined whether seasonality could be used as leverage in creation of effective control strategies. Results We found models that used seasonal averaging could grossly overestimate infection burden and underestimate control outcomes in highly seasonal environments. We showed that proper intra-seasonal timing of control measures could make marked improvement on the long-term burden reduction for Schistosoma transmission control, and we identified the optimal timing for each intervention. Seasonal snail control, implemented alone, was less effective than mass drug administration, but could provide additive impact in reaching control and elimination targets. Conclusion Seasonal variation makes Schistosoma transmission less sustainable and easier to control than predicted by earlier modeling studies.

scholarly journals Macro-parasite transmission in dynamic seasonal environment: Basic Reproductive Number, endemicity, and control

2019 ◽  
Author(s):  
Q. Huang ◽  
D. Gurarie ◽  
M. Ndeffo-Mbah ◽  
E. Li ◽  
CH. King
Keyword(s):  
Intermediate Host ◽  
Worm Burden ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Optimal Time ◽  
Optimal Timing ◽  
Snail Population ◽  
Seasonal Environment ◽  
Combined Strategy ◽  
And Control

AbstractSeasonality of transmission environment, which includes snail populations and habitats, or human-snail contact patterns, can affect the dynamics of schistosomiasis infection, and control outcomes. Conventional modeling approaches often ignore or oversimplify it by applying ‘seasonal mean’ formulation. Mathematically, such ‘averaging’ is justified when model outputs/quantities of interest depend linearly on input variables. That is not generally the case for macroparasite transmission models, where model outputs are nonlinear functions of seasonality fashion.Another commonly used approach for Schistosomiasis modeling is a reduction of coupled human-snail system to a single ‘human equation’, via quasi-stationary snail (intermediate host) dynamics. The basic questions arising from these approaches are whether such ‘seasonal averaging’ and ‘intermediate host reduction’ are suitable for highly variable/seasonal environments, and what implications these methods have on models’ predictive potential of control interventions.Here we address these questions by using a combination of mathematical analysis and numerical simulation of two commonly used models for macroparasite transmission, MacDonald (MWB), and stratified worm burden (SWB) snail-human systems. We showed that predictions from ‘seasonal averaging’ models can depart significantly from those of quasi-stationary models. Typically, seasonality would lower endemicity and sustained infection, vs. stationary system with comparable transmission inputs. Furthermore, discrepancies between the two models (‘seasonal’ and its ‘stationary mean’) increase with amplitude (or variance) of seasonality. So sufficiently high variability can render infection unsustainable. Similar discrepancies were observed between coupled and reduced ‘single host’ models, with reduced model overpredicting sustained endemicity. Seasonal variability of transmission raises the question of optimal control timing. Using dynamic simulation, we show that optimal timing of repeated MDA is about half season past the snail peak, where snail population attains its minimal value. Compared to sub-optimal timing, such strategy can reduce human worm burden by factor 2 after 5-6 rounds of MDA. We also extended our models for dynamic snail populations, which allowed us to study the effect of repeated molluscicide, or combined strategy (MDA + molluscicide). The optimal time for molluscicide alone is the end or the start of season, and combined strategy can give additional reduction, and in some cases lead to elimination.Overall, reduced sustainability in seasonal environment makes it more amenable to control interventions, compared to stationary environment.

New data on the occurrence of Acanthocephala in Antarctic Amphipoda

2010 ◽  
Vol 55 (2) ◽  
Author(s):  
Zdzisław Laskowski ◽  
Witold Jeżewski ◽  
Krzysztof Zdzitowiecki
Keyword(s):  
Intermediate Host ◽  
Parasite Species ◽  
South Shetland Islands ◽  
Polluted Water ◽  
Admiralty Bay ◽  
Shetland Islands ◽  
Total Prevalence ◽  
First Time ◽  
Cheirimedon Femoratus

AbstractIn total, 6401 amphipods, including 5707 Cheirimedon femoratus, caught at the Galindez Island (Argentine Islands, Western Antarctica) were examined for the presence of cystacanths and advanced acanthellae of Acanthocephala. Two parasite species, Corynosoma pseudohamanni Zdzitowiecki, 1984 and Metacanthocephalus johnstoni Zdzitowiecki, 1983, were found in the haemocoeloma of C. femoratus. Total prevalence was 1.19%, that of C. pseudohamanni 0.68% and of M. johnstoni 0.51%. Additionally, 8 of 1416 C. femoratus caught in the Admiralty Bay (South Shetland Islands) were found to be infected with C. pseudohamanni and free of M. johnstoni. The representative of the genus Metacanthocephalus was found in the intermediate host for the first time. C. pseudohamanni was more abundant at the Galindez Island (prevalence 0.68%) than in the Admiralty Bay (prevalence 0.42% in previous investigations and 0.56% in present ones). Amphipods harboured usually one or rarely two acanthocephalans of one species. Both parasites were more abundant in amphipods caught in the polluted water closely to the Vernadsky Station than in the Mick Channel, farther from the station (prevalence 0.77% vs. 0.51% for C. pseudohamanni and 0.64% vs. 0.26% for M. johnstoni).

SOME MICRO-ECOLOGICAL FACTORS INFLUENCING THE POPULATION DYNAMICS OF SCHISTOSOMIASIS INTERMEDIATE HOST SNAILS IN KHARTOUM STATE, SUDA

2016 ◽  
Vol 4 (8) ◽  
pp. 147-151
Author(s):  
A. Zakaria Mohamed ◽  
Azzam Afifi ◽  
Yassir Sulieman ◽  
Theerakamol Pengsakul
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Intermediate Host ◽  
Population Growth Rate ◽  
Ecological Factors ◽  
Water Bodies ◽  
Snail Population ◽  
Factors Influencing ◽  
High Turbidity

This study was conducted to determine the role of some micro-ecological factors influencing the population dynamics of schistosomiasis intermediate host snails in the water bodies of Khartoum State, Sudan. The results show that the air and water temperature play a significant role in the determination of snail growth, a gradual increase of air and water temperate causing an increase in the snail population growth rate with the peak in summer. Water of high turbidity and high current speed caused a drop in the snail population. Vegetation cover in water bodies showed a significant effect on the snail population, the denser the cover the higher the snail population growth rate.

First molecular identification of Ascocotyle (Phagicola) longa in its first intermediate host the mud snail Heleobia australis

2015 ◽  
Vol 60 (4) ◽  
Author(s):  
Pilar Alda ◽  
Nicolás Bonel ◽  
Carlos J. Panei ◽  
Néstor J. Cazzaniga ◽  
Sergio R. Martorelli
Keyword(s):  
Intermediate Host ◽  
Bahía Blanca Estuary ◽  
Larval Stages ◽  
Mud Snail ◽  
Total Prevalence ◽  
Second Intermediate Host ◽  
Species Specific ◽  
Dna Primers ◽  
First Intermediate Host ◽  
Blanca Estuary

AbstractThis is the first study that used species-specific DNA primers to confirm the presence of the heterophyid Ascocotyle (Phagicola) longa Ransom, 1920 in its first intermediate host. The larval stages (rediae and cercariae) of this parasite were morphologically and genetically identified in the gonad of the intertidal mud snail Heleobia australis (d’Orbigny, 1835) (Cochliopidae) in the Bahía Blanca estuary, Argentina. In addition, we asked whether the prevalence in H. australis varied between seasons. Mullets - the second intermediate host of this heterophyid - migrate in estuaries during the warmer seasons and it is expected that piscivorous birds and mammals - the definitive hosts - prey more intensively on this species at those times. Thus, the number of parasite eggs released into the tidal flat within their feces should be higher, thereby increasing the ingestion of the parasite by H. australis.We therefore expected a higher prevalence of A. (P.) longa in H. australis in the Bahía Blanca estuary during spring and summer than autumn and winter. We found that 16 out of 2,744 specimens of H. australis had been infected with A. (P.) longa (total prevalence of 0.58%). Nonetheless, the prevalence showed no significant variation between seasons. Hence, we discuss an alternative scenario where the lack of seasonal changes might be mostly related to the permanent residence of definitive hosts in the estuary and not to the seasonal recruitment of mullets. Finally, we highlight the need for more experimental and comparative approaches in order to understand the diagnosis and geographical distribution of this worldwide heterophyid.

Studies on the life cycle of Asymphylodora tincae (Modeer, 1790) (Trematoda: Monorchiidae) in a small lake near Amsterdam

1979 ◽  
Vol 53 (1) ◽  
pp. 79-89 ◽  
Author(s):  
Elisabeth van den Broek ◽  
Nienke de Jong
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Morphological Structure ◽  
Morphological Description ◽  
Snail Species ◽  
Tinca Tinca ◽  
Small Lake ◽  
Bithynia Tentaculata ◽  
Second Intermediate Host

ABSTRACTAspects of the life cycle of Asymphylodora tincae have been studied in a small lake near Amsterdam. Bithynia tentaculata, being the only snail species that was very numerous in the lake, was the first as well as the main second intermediate host; adult trematodes were found exclusively in the tench, Tinca tinca. A small part of the cercariae that penetrate into B. tentaculata was able to develop into progenetic specimens. A morphological description is given of the following stages of A. tincae: adult, egg, redia, cercariaeum, metacercaria and progenetic stage. The cercariaeum is identified as Cercariaeum paludinae impurae De Filippi, 1854.It is concluded that A. tincae is a species, capable of large variation regarding both morphological structure (e.g. body spination, size) and life cycle.

scholarly journals OVICIDAL EFFECT OF PIPERACEAE SPECIES ON Biomphalaria glabrata, Schistosoma mansoni HOST

2013 ◽  
Vol 55 (6) ◽  
pp. 421-424 ◽  
Author(s):  
Ludmila Nakamura Rapado ◽  
Priscila Orechio de Moraes Lopes ◽  
Lydia Fumiko Yamaguchi ◽  
Eliana Nakano
Keyword(s):  
Public Health ◽  
Disease Control ◽  
Intermediate Host ◽  
Biomphalaria Glabrata ◽  
Snail Population ◽  
Intermediate Host Snail ◽  
Blastula Stage ◽  
Public Health Importance ◽  
Host Snail ◽  
Ovicidal Effect

SUMMARY Schistosomiasis is a neglected disease with public health importance in tropical and subtropical regions. An alternative to the disease control is the use of molluscicides to eliminate or reduce the intermediate host snail population causing a reduction of transmission in endemic regions. In this study nine extracts from eight Piperaceae species were evaluated against Biomphalaria glabrata embryos at blastula stage. The extracts were evaluated in concentrations ranging from 100 to 10 mg/L. Piper crassinervium and Piper tuberculatum extracts were the most active (100% of mortality at 20 mg/L and 30 mg/L respectively).

Assessing cercarial transmission of Cyathocotyle bushiensis and Sphaeridiotrema pseudoglobulus by use of sentinel snails

1994 ◽  
Vol 72 (5) ◽  
pp. 885-891 ◽  
Author(s):  
Dwayne A. W. Lepitzki ◽  
Marilyn E. Scott ◽  
J. Daniel McLaughlin
Keyword(s):  
Spatial Heterogeneity ◽  
Temporal Variation ◽  
Spatial And Temporal Variation ◽  
Temporal Differences ◽  
Size Classes ◽  
Naturally Occurring ◽  
Bithynia Tentaculata ◽  
Low Levels ◽  
Different Levels ◽  
Cyathocotyle Bushiensis

Sentinel snails (Bithynia tentaculata) were used to assess spatial and temporal variation in cercarial transmission of Cyathocotyle bushiensis and Sphaeridiotrema pseudoglobulus at two field locations in southern Quebec and southeastern Ontario from mid-August to the end of October, 1989. Sentinels acquired infections with both digeneans; however, low levels of metacercariae of C. bushiensis precluded any conclusions regarding transmission of this parasite from being reached. In contrast, extensive spatial heterogeneity existed in the S. pseudoglobulus – snail system. Sentinel snails within 10 m of each other were apparently exposed to vastly different levels of naturally occurring cercariae. All size classes of sentinels were apparently equally susceptible to cercarial infections but no consistent temporal differences in infection levels were found.

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