scholarly journals Community diversity reduces Schistosoma mansoni transmission, host pathology and human infection risk

2009 ◽  
Vol 276 (1662) ◽  
pp. 1657-1663 ◽  
Author(s):  
Pieter T.J Johnson ◽  
Peder J Lund ◽  
Richard B Hartson ◽  
Timothy P Yoshino
Keyword(s):  
Community Structure ◽  
Schistosoma Mansoni ◽  
Host Density ◽  
Biodiversity Loss ◽  
Infection Risk ◽  
Human Infection ◽  
Host Community ◽  
Community Diversity ◽  
Complex Life Cycle ◽  
Intermediate Hosts

Global biodiversity loss and disease emergence are two of the most challenging issues confronting science and society. Recently, observed linkages between species-loss and vector-borne infections suggest that biodiversity may help reduce pathogenic infections in humans and wildlife, but the mechanisms underlying this relationship and its applicability to a broader range of pathogens have remained speculative. Here, we experimentally evaluated the effects of host community structure on transmission of the human pathogen, Schistosoma mansoni , which alternates between snail intermediate hosts and vertebrate definitive hosts. By manipulating parasite exposure and community diversity, we show that heterospecific communities cause a 25–50 per cent reduction in infection among snail hosts ( Biomphalaria glabrata ). Infected snails raised alongside non-host snails ( Lymnaea or Helisoma sp.) also produced 60–80 per cent fewer cercariae, suggesting that diverse communities could reduce human infection risk. Because focal host density was held constant during experiments, decreases in transmission resulted entirely from diversity-mediated pathways. Finally, the decrease in infection in mixed-species communities led to an increase in reproductive output by hosts, representing a novel example of parasite-mediated facilitation. Our results underscore the significance of community structure on transmission of complex life-cycle pathogens, and we emphasize enhanced integration between ecological and parasitological research on the diversity–disease relationship.

Posthodiplostomum cuticola(Digenea: Diplostomatidae) in intermediate fish hosts: factors contributing to the parasite infection and prey selection by the definitive bird host

Parasitology ◽  
2004 ◽  
Vol 129 (6) ◽  
pp. 761-770 ◽  
Author(s):  
M. ONDRAČKOVÁ ◽  
A. šIMKOVÁ ◽  
M. GELNAR ◽  
P. JURAJDA
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Host Density ◽  
Parasite Infection ◽  
Fish Host ◽  
Snail Host ◽  
Complex Life Cycle ◽  
Adult Fish ◽  
Fish Community Structure ◽  
Fish Hosts

Infection parameters ofPosthodiplostomum cuticola, a digenean parasite with a complex life-cycle, were investigated in fish (the second intermediate host) from 6 floodplain water bodies over 2 years. A broad range of factors related to abiotic characteristics of localities, density of the first intermediate (planorbid snails) and definitive (wading birds) hosts and fish community structure were tested for their effects onP. cuticolainfection in juvenile and adult fish. Characters of the littoral zone and flood duration were found to be important factors for the presence of the first intermediate and definitive hosts. Visitation time of definitive bird hosts was also related to adult fish host density. Localities withP. cuticolainfected fish were visited by a higher number of bird species. Infection ofP. cuticolain fish and similarities in infection among fish host assemblages were correlated with fish host density and fish species composition. Parasite infection in both adult and juvenile fishes was associated with the slope of the bank and the bottom type, in particular in juvenile fish assemblages with snail host density. We conclude that habitat characteristics, snail host density and fish community structure contribute significantly toP. cuticolainfection in fish hosts.

scholarly journals Dicrocoelium DendriticumInfection in a Patient with Crohn’s Disease

2008 ◽  
Vol 22 (6) ◽  
pp. 571-573 ◽  
Author(s):  
Franzjosef Schweiger ◽  
Magdalena Kuhn
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Medical Literature ◽  
Present Report ◽  
Land Snail ◽  
Human Infection ◽  
Complex Life Cycle ◽  
Intermediate Hosts ◽  
Animal Liver ◽  
Second Intermediate Host

Infection withDicrocoelium dendriticumin humans is rarely reported in the medical literature. This liver fluke, which commonly infects ruminants, has a complex life cycle with two intermediate hosts – the land snail and the ant. True human infection occurs by ingestion of the second intermediate host, but spurious infections have occurred after consumption of undercooked animal liver. The present report describes a patient with active Crohn’s disease whose stool containedD dendriticumeggs. A brief discussion of the medical literature is presented.

Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

1989 ◽  
Vol 47 ◽  
pp. 962-963
Author(s):  
Betty Ruth Jones ◽  
Steve Chi-Tang Pan
Keyword(s):  
Nervous System ◽  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Snail Host ◽  
Complex Life Cycle ◽  
Rational Approach ◽  
Effective Control ◽  
The Social ◽  
Social And Economic Development ◽  
Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

Temperature and multiple parasites combine to alter host community structure

Oikos ◽  
2021 ◽  
Author(s):  
Olwyn Friesen ◽  
Robert Poulin ◽  
Clément Lagrue
Keyword(s):  
Community Structure ◽  
Host Community

Susceptibilities of Various Snail Intermediate Hosts of Schistosoma mansoni to Different Strains of the Parasite

1965 ◽  
Vol 39 (4) ◽  
pp. 363-376 ◽  
Author(s):  
M.F.A. Saoud
Keyword(s):  
Puerto Rico ◽  
Schistosoma Mansoni ◽  
Intermediate Hosts ◽  
Considerable Evidence ◽  
The Past ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Different Strains ◽  
Host Parasite ◽  
Comprehensive Studies

In the past two decades, considerable evidence has accumulated in the literature about the differences in the susceptibility of various intermediate hosts of Schistosoma mansoni to different strains of the parasite. Comprehensive studies on this aspect of host-parasite relationship have been published by Files & Cram (1949), Abdel-Malek (1950) and Files (1951). The results of more recent studies have been reported by Wright (1962) and Saoud (1964).In the present paper, the writer has studied the susceptibility of four intermediate hosts of S. mansoni from Brazil, Puerto Rico, Egypt and Tanganyika to some strains of the parasite.

Correlation between Experimental and Human Infection with Schistosoma Mansoni

Nature ◽  
1964 ◽  
Vol 201 (4922) ◽  
pp. 899-901 ◽  
Author(s):  
KENNETH S. WARREN
Keyword(s):  
Schistosoma Mansoni ◽  
Human Infection

scholarly journals Interaction between typical sulfonamides and bacterial diversity in drinking water

2018 ◽  
Vol 16 (6) ◽  
pp. 914-920 ◽  
Author(s):  
Qing Wu ◽  
Shuqun Li ◽  
Xiaofei Zhao ◽  
Xinhua Zhao
Keyword(s):  
Drinking Water ◽  
Community Structure ◽  
Microbial Community ◽  
Bacterial Community ◽  
Bacterial Diversity ◽  
Microbial Community Structure ◽  
Antibiotic Use ◽  
Community Diversity ◽  
Wide Range ◽  
Growth Of Bacteria

Abstract The abuse of antibiotics is becoming more serious as antibiotic use has increased. The sulfa antibiotics, sulfamerazine (SM1) and sulfamethoxazole (SMZ), are frequently detected in a wide range of environments. The interaction between SM1/SMZ and bacterial diversity in drinking water was investigated in this study. The results showed that after treatment with SM1 or SMZ at four different concentrations, the microbial community structure of the drinking water changed statistically significantly compared to the blank sample. At the genus level, the proportions of the different bacteria in drinking water may affect the degradation of the SM1/SMZ. The growth of bacteria in drinking water can be inhibited after the addition of SM1/SMZ, and bacterial community diversity in drinking water declined in this study. Furthermore, the resistance gene sul2 was induced by SM1 in the drinking water.

Heterotrophic Bacterial Community Structure of Multistage Biofilters in a Commercial Pufferfish Takifugu rubripes RAS

2013 ◽  
Vol 726-731 ◽  
pp. 1621-1627 ◽  
Author(s):  
Zhu Chen ◽  
Ying Liu ◽  
Liang Zi Liu ◽  
Xiao Jing Wang ◽  
Zhi Pei Liu ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Bacterial Community ◽  
Bacterial Community Structure ◽  
Heterotrophic Bacteria ◽  
Diversity Index ◽  
Community Diversity ◽  
Takifugu Rubripes ◽  
Recirculating Aquaculture ◽  
Microbial Resources

The success of a recirculating aquaculture system (RAS) greatly depends on the structure, dynamics and activities of microbial community. Heterotrophic bacteria as the major members play various roles. The heterotrophic bacterial community structure in threestaged biofilters was studied using four different media. 228 isolates belonging to 77species were obtained and affiliated toGammaproteobacteria,Alphaproteobacteria,Bacteroidetes,Firmicutes,ActinobacteriaandBetaproteobacteria.Gammaproteobacteriawas the predominant group. The concurrence was found between potential pathogens (VibrioandShewanella) and probiotics (BacillusandPseudomonas). On the basis of community diversity index, we could infer that differences existed between stages, and the diversity index increased along the biofilters. A comprehensive understanding of microbial community in RAS will be in favor of utilization of microbial resources and optimizing the culture systems' operation.

scholarly journals Habitat heterogeneity drives scale-dependent biodiversity loss in a temperate marine ecosystem

2018 ◽  
Author(s):  
Samuel Starko ◽  
Lauren Bailey ◽  
Elandra Creviston ◽  
Katelyn James ◽  
Alison Warren ◽  
...  
Keyword(s):  
Habitat Heterogeneity ◽  
Spatial Scales ◽  
Marine Ecosystem ◽  
Habitat Type ◽  
Extreme Temperature ◽  
Biodiversity Loss ◽  
Community Diversity ◽  
Diversity Loss ◽  
Biological Responses ◽  
Local Wave

AbstractBiodiversity loss is driven by interacting factors operating at different spatial scales. Yet, there remains uncertainty as to how fine-scale environmental conditions mediate biological responses to broad-scale stressors. We surveyed mid-latitude kelp bed habitats to determine whether local habitat heterogeneity has mediated changes in community diversity after more than two decades of extreme temperature events, most notably the 2013-2016 heat wave. Local wave exposure conditions were key in determining responses, with some habitats remaining stable and others experiencing near complete diversity loss, leading to local declines without regional extinctions. Wave-sheltered shores, which saw the largest declines, are a very common habitat type in the Northeast Pacific and may be especially sensitive to climate-related losses in kelp diversity and abundance. Our findings highlight how local gradients can interact with global drivers to facilitate diversity loss and demonstrate how incorporating differences between habitat patches can be essential to capturing scale-dependent biodiversity loss across the landscape.

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