Component community dynamics of larval trematodes in the freshwater snail Semisulcospira nakasekoae in the Uji River, central Japan

2004 ◽  
Vol 78 (4) ◽  
pp. 361-370 ◽  
Author(s):  
M. Urabe ◽  
M Hinoue
Keyword(s):  
Community Dynamics ◽  
Positive Association ◽  
Freshwater Snail ◽  
Host Population ◽  
Multiple Infections ◽  
Trematode Species ◽  
Patent Period ◽  
Component Community ◽  
Temporal And Spatial ◽  
Stable Size Distribution

AbstractThe component community of larval trematodes in the freshwater snail Semisulcospira nakasekoae (Caenogastropoda: Sorbeoconcha: Pleuroceridae) was surveyed over 13 months from April 1996 to April 1997 inclusive. Temporal and spatial fluctuation of trematode prevalence, the frequency of multiple infections, and the duration of cercarial shedding were examined as factors that might affect trematode community structure. The spatial prevalence of some species varied significantly, but the dynamics were too small to allow an explanation of the overall pattern. The prevalence of sanguinicolids fluctuated temporally, despite a stable size distribution in the host populations (> 6.0 mm shell width), suggesting the life-cycle phenology of this species. Some pairs of species had statistically positive associations, but no pairs had negative associations. This shows the importance of positive association possibly as a result of suppression of the host defensive response on trematode community structures in molluscan hosts. The length of the patent period, which is part of the persistent period, varied among trematode species, suggesting it to be one of the factors determining prevalence in the host population.

Temporal variations in the infection of a population of Cerithidea cingulata by larval trematodes in Kuwait Bay

2000 ◽  
Vol 74 (1) ◽  
pp. 17-22 ◽  
Author(s):  
W.Y. Al-Kandari ◽  
J. Abdul-Salam ◽  
R. Meakins
Keyword(s):  
Temporal Variations ◽  
Multiple Infections ◽  
Trematode Species ◽  
Snail Population ◽  
Component Community ◽  
Shell Size ◽  
Kuwait Bay ◽  
Cerithidea Cingulata ◽  
Trematode Infections ◽  
Prevalent Species

AbstractThe prosobranch gastropod Cerithidea cingulata (Gastropoda: Potamididae) in Kuwait Bay was examined for larval trematode infections over a 17-month period. A total of 2537 snails were examined and 1265 (49.9%) found to be infected with one or more species of trematodes. The component community in the snail comprised 12 species representing the families Cyathocotylidae (2), Echinostomatidae (2), Haplosplanchnidae (1), Heterophyidae (2), Microphallidae (1), Philophthalmidae (2), Plagiorchiidae (1) and Schistosomatidae (1). Cyathocotylid II (41.6%) was by far the most prevalent species followed by the microphallid (3.9%), the two species comprised 90% of the total trematode fauna. The prevalence of infection increased with shell size and was significantly higher in male (47%) than female (33%) snails. Multiple infections were observed in only 15 (1.2%) of the infected snails; cyathocotylid I and cyathocotylid II combination occurred 14 times and heterophyid I and the microphallid occurred once. Trematode species were more diverse and prevalent in winter, and cercarial shedding peaked in summer. Behaviour of the definitive host and snail population dynamics were probably the major contributors to the detected temporal pattern in the infections.

The effect of the acanthocephalan Pomphorhynchus laevis upon the respiration of its intermediate host, Gammarus pulex

Parasitology ◽  
1974 ◽  
Vol 68 (2) ◽  
pp. 271-284 ◽  
Author(s):  
A. E. Rumpus ◽  
C. R. Kennedy
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Host Population ◽  
Gammarus Pulex ◽  
Multiple Infections ◽  
Pomphorhynchus Laevis ◽  
Respiration Rates ◽  
Physiological Processes ◽  
Stage Of Development ◽  
Host Parasite

The respiration rates of individual Gammarus pulex infected by larval Pomphorhynchus laevis were investigated with particular reference to the stage of development of the host and parasite and to the water temperature. At 20°C the oxygen consumption of Gammarus of all sizes was reduced by an average of 19·3 % by the presence of cystacanths of the parasite, but was unaffected by the presence of acanthellae. It is considered that the small size of this larval stage, in relation to that of its host, is responsible for the failure to detect an effect. Multiple infections did not exert any greater effect upon host respiration than single cystacanths, nor did it appear that the parasite had different effects upon hosts of different sexes. At 10°C no significant differences were observed between the respiration rates of infected and uninfected gammarids. The parasite was probably still depressing the host respiration rate at this temperature, but the oxygen uptake of G. pulex is so low that the differences between infected and uninfected individuals were too small to be detected. The parasite has a direct effect upon the physiological processes of the host, but neither the mechanism of this nor the reasons for the different effects found in different host-parasite systems are yet understood. Despite the pronounced effect of P. laevis on respiration of individual hosts, its effect upon the oxygen consumption of a natural host population is small since only a small proportion of the population carries infections and water temperatures remain below 10°C for over half the year.

Parasite infection and host dynamics in a naturally fluctuating rodent population

2012 ◽  
Vol 90 (9) ◽  
pp. 1149-1160 ◽  
Author(s):  
J.C. Winternitz ◽  
M.J. Yabsley ◽  
S.M. Altizer
Keyword(s):  
Population Density ◽  
Experimental Studies ◽  
Host Density ◽  
Positive Association ◽  
Population Cycles ◽  
Host Population ◽  
Reproductive Status ◽  
Vole Cycles ◽  
Host Infection ◽  
The Impact

Parasites can both influence and be affected by host population dynamics, and a growing number of case studies support a role for parasites in causing or amplifying host population cycles. In this study, we examined individual and population predictors of gastrointestinal parasitism on wild cyclic montane voles ( Microtus montanus (Peale, 1848)) to determine if evidence was consistent with theory implicating parasites in population cycles. We sampled three sites in central Colorado for the duration of a multiannual cycle and recorded the prevalence and intensity of directly transmitted Eimeria Schneider, 1875 and indirectly transmitted cestodes from a total of 267 voles. We found significant associations between host infection status, individual traits (sex, age, and reproductive status) and population variables (site, trapping period, and population density), including a positive association between host density and cestode prevalence, and a negative association between host density and Eimeria prevalence. Both cestode and Eimeria intensity correlated positively with host age, reproductive status, and population density, but neither parasite was associated with poorer host condition. Our findings suggest that parasites are common in this natural host, but determining their potential to influence montane vole cycles requires future experimental studies and long-term monitoring to determine the fitness consequences of infection and the impact of parasite removal on host dynamics.

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.

LARVAL TREMATODES PARASITIZING LYMNAEA STAGNALIS APPRESSA SAY IN ONTARIO WITH EMPHASIS ON MULTIPLE INFECTIONS

1963 ◽  
Vol 41 (6) ◽  
pp. 937-941 ◽  
Author(s):  
T. K. R. Bourns
Keyword(s):  
Lymnaea Stagnalis ◽  
Multiple Infections ◽  
Trematode Species ◽  
Subsequent Infection ◽  
Trematode Infection

A total of 1659 Lymnaea stagnalis appressa Say were examined for trematode infection. Of these, 571 shed one, 215 shed two, and 15 shed three species of cercariae. Most of the snails, including at least one with three other species, contained metacercariae of Cotylurus flabelliformis. It is suggested that infection of snails by one trematode species may increase or decrease the mollusc's susceptibility to subsequent infection by other trematode larvae.

Patterns of variation in parasite component communities and infracommunities of a littoral fish species from the northern coast of Chile

2012 ◽  
Vol 88 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Vania Henríquez ◽  
M. Teresa González
Keyword(s):  
Fish Population ◽  
Host Population ◽  
Northern Coast ◽  
Component Community ◽  
Geographic Scale ◽  
Parasite Communities ◽  
Individual Host ◽  
Hierarchical Levels ◽  
Geographical Scale ◽  
Parasite Assemblages

AbstractThe structure and similarity of the parasite communities of fish can be evaluated at the component community (CC) and infracommunity (IC) levels. Both hierarchical levels have been used to assess parasite variations in fish at large (biogeographic) scales. However, studies evaluating the consistency between these two hierarchical levels at smaller geographical scales are scarce. In this study, the parasite assemblages of 124 Paralabrax humeralis collected by local fishermen by spear fishing at four sites (El Fierro, EF; P. Angamos, PA; Santa María, ISM; San Jorge, BSJ) in northern Chile were compared to assess the variability (or similarity) of their CCs and ICs at a limited geographical scale using multivariate analysis. At the IC level, discriminant analyses showed that P. humeralis parasite communities varied significantly among sites; 70% of ectoparasite ICs were correctly assigned to each site, but only 55% of helminth parasite ICs were correctly classified. At the CC level, the composition of parasite communities as assessed by correspondence analyses varied significantly between sites. Tagia sp., Neobenedenia sp. and Philometra sp. were associated with BSJ, ISM and PA, respectively; Corynosoma sp. and most digeneans were associated with both ISM and EF. Analysis of similarities (ANOSIM) showed significant variations in the degree of similarity between P. humeralis CCs from different sites, but not between ICs. Variations between CCs from different sites reflect fish population processes (e.g., population age, reproductive segregation) and the particular conditions of their respective habitats, whereas ICs reflect individual host movements. This study demonstrated that, when examined at a limited geographical scale, IC is better than CC at capturing the local pool of parasite assemblages when host populations are spatially segregated. Therefore, in this study, it is demonstrated that at a small geographic scale, CC variations are not reflected by IC, when host population is spatially segregated.

scholarly journals Heterogeneity in transmission parameters of hookworm infection within the baseline data from the TUMIKIA study in Kenya

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
James E. Truscott ◽  
Alison K. Ower ◽  
Marleen Werkman ◽  
Katherine Halliday ◽  
William E. Oswald ◽  
...  
Keyword(s):  
Negative Binomial ◽  
Positive Association ◽  
Monitoring And Evaluation ◽  
Host Population ◽  
Transmission Model ◽  
High Coverage ◽  
Study Region ◽  
Transmission Parameters ◽  
Parasite Aggregation ◽  
The Impact

Abstract Background As many countries with endemic soil-transmitted helminth (STH) burdens achieve high coverage levels of mass drug administration (MDA) to treat school-aged and pre-school-aged children, understanding the detailed effects of MDA on the epidemiology of STH infections is desirable in formulating future policies for morbidity and/or transmission control. Prevalence and mean intensity of infection are characterized by heterogeneity across a region, leading to uncertainty in the impact of MDA strategies. In this paper, we analyze this heterogeneity in terms of factors that govern the transmission dynamics of the parasite in the host population. Results Using data from the TUMIKIA study in Kenya (cluster STH prevalence range at baseline: 0–63%), we estimated these parameters and their variability across 120 population clusters in the study region, using a simple parasite transmission model and Gibbs-sampling Monte Carlo Markov chain techniques. We observed great heterogeneity in R0 values, with estimates ranging from 1.23 to 3.27, while k-values (which vary inversely with the degree of parasite aggregation within the human host population) range from 0.007 to 0.29 in a positive association with increasing prevalence. The main finding of this study is the increasing trend for greater parasite aggregation as prevalence declines to low levels, reflected in the low values of the negative binomial parameter k in clusters with low hookworm prevalence. Localized climatic and socioeconomic factors are investigated as potential drivers of these observed epidemiological patterns. Conclusions Our results show that lower prevalence is associated with higher degrees of aggregation and hence prevalence alone is not a good indicator of transmission intensity. As a consequence, approaches to MDA and monitoring and evaluation of community infection status may need to be adapted as transmission elimination is aimed for by targeted treatment approaches.

Helminth community structure and pattern in two allopatric populations of a nonmigratory waterfowl species (Anas fulvigula)

1996 ◽  
Vol 74 (7) ◽  
pp. 1253-1259 ◽  
Author(s):  
Alan M. Fedynich ◽  
Danny B. Pence ◽  
Paul N. Gray ◽  
James F. Bergan
Keyword(s):  
Habitat Diversity ◽  
Host Population ◽  
Helminth Species ◽  
Feeding Guilds ◽  
Feeding Guild ◽  
Component Community ◽  
Recurrent Group ◽  
Mottled Duck ◽  
Anas Fulvigula ◽  
Group Members

Helminth communities of mottled ducks (Anas fulvigula) from Florida and Texas were species rich and diverse. The helminth component community in the mottled duck population from Texas contained more species than were found in the Florida host population. However, infracommunities of birds from Florida and Texas contained 9.5 ± 0.7 (mean ± SE) and 9.3 + 0.7 species, respectively. Similarity indices indicated less commonality of helminth species between the 2 host populations; 23 of the 42 species found across the 2 populations co-occurred. Eight helminth species from each host population were recurrent group or associate members; however, only 3 species (Amidostomum acutum, Capillaria contorta, and Tetrameres spp.) maintained group membership across both host populations. Maritrema paracadiae and Psilochasmus oxyurus were absent in birds from Florida but were recurrent group members in the host population from Texas. Only 2 recurrent group members (A. acutum and Epomidiostomum uncinatum) in birds from Florida were members of the same feeding guild and shared the same microhabitat. Three distinct feeding guilds, each containing 2 species, were found in birds from Texas. Results suggest that habitat diversity of the host plays an important part in determining species richness; however, important helminth species in both mottled duck populations are those commonly found in other Anatini from North America.

scholarly journals Fertility Intentions and Views on Gender Roles: Russian Women in Estonia from an Origin-destination Perspective

2019 ◽  
Vol 43 ◽  
Author(s):  
Allan Puur ◽  
Hanna Vseviov ◽  
Liili Abuladze
Keyword(s):  
Gender Roles ◽  
Positive Association ◽  
Gender Role Attitudes ◽  
Fertility Intentions ◽  
Host Population ◽  
Second Child ◽  
Logistic Regression Models ◽  
Cultural Maintenance ◽  
Childbearing Intentions ◽  
The Difference

In this article we investigate fertility intentions of Russian women in Estonia from an origin-destination perspective. Russian migrants to Estonia and their descendants are compared with women in the sending and host countries in order to identify similarities and differences in intended transitions to first, second and third births. The study is based on the Estonian and Russian Generations and Gender Surveys, which were conducted in 2004/2005, and employs logistic regression models. The dependent variables are intentions to become a mother, to have a second child, or to have a third child. The hypotheses for the study are mainly derived from the adaptation, cultural maintenance, and selection (characteristics) perspectives. We also incorporate attitudes towards gender roles into the models, which have proven to be a salient factor in shaping childbearing intentions, but have seldom been considered in studies of migrant fertility.Our results lend support to both the adaptation and cultural maintenance perspectives. In accord with the latter, the similarity between the childbearing intentions of Russian migrants and their descendants in Estonia and those of their counterparts in Russia suggests that socialisation to the ethnic subculture has prevailed over the influence of the host society. We attribute this outcome to contextual features that have retarded integration processes. By contrast, we observe that proficiency in the host country language, residence in areas where the host population constitutes a large majority and having a native partner significantly contribute to the adaptation of migrants’ intentions to have another child to those of the host population. These results provide support to the adaptation argument. Finally, our study reveals a positive association between egalitarian views on gender roles and women’s intentions to have another child. However, variation in gender role attitudes accounts for a relatively minor part of the difference in intended fertility between the groups addressed in this study.* This article belongs to a special issue on migrant fertility.

scholarly journals Virulence evolution of multiple infections with vertically and horizontally transmitted fungal species in a natural plant system

2020 ◽  
Author(s):  
Kai Fang ◽  
Jie Zhou ◽  
Lin Chen ◽  
Yu-Xuan Li ◽  
Ai-Ling Yang ◽  
...  
Keyword(s):  
Invasive Plant ◽  
Horizontal Transmission ◽  
Experimental Studies ◽  
Fungal Species ◽  
Host Population ◽  
Transmission Mode ◽  
Multiple Infections ◽  
Plant Host ◽  
Susceptible Host ◽  
Virulence Evolution

AbstractThe virulence evolution of multiple infections of parasites from the same species has been modelled widely in evolution theory, and the trajectories of evolution are relevant to parasite transmission mode, as well as to parasite and host population dynamics. However, experimental studies on this topic remain scarce, particularly regarding multiple infections by different parasite species. In this study, we employed the invasive plant Ageratina adenophora to verify the predictions made by the model. We observed that A. adenophora was a highly susceptible host to phylogenetically diverse foliar pathogens with mixed vertical and horizontal transmission within leaf spots. The pathogen community structure at the leaf spot level was determined by transmission mode. Over time, the pathogen community decreased in diversity; meanwhile, the vertically transmitted pathogens exhibited decreased virulence to the host A. adenophora, but the horizontally transmitted pathogens exhibited increased virulence to the host. Our results demonstrate that the predictions of classical models are still valid in a complex environment. Moreover, we propose that it is very important to determine whether the primary foliar pathogen of a given plant host is relevant to seedborne fungi, as this characteristic is an important factor in understanding pathogen-host interactions.

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