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At least 199 records · Page 11Linked to original sources
PubMed2006

Contact rates and exposure to inter-species disease transmission in mountain ungulates.

The risk for a pathogen to cross the species barrier depends on the rate of efficient contacts between the species. However, contact rates between species have rarely been estimated from observations. Here we estimate contact rates and exposure of chamois Rupicapra rupicapra and Alpine ibex Capra ibex exposed to domestic pasteurellosis and brucellosis carried by sheep or cattle herds summering in mountain pastures. We use field observation data on animal positions treated in a geographic information system (GIS). Comparing 10 pastures, we show that the management of domestic herds influences the risk of inter-species transmission. Exposure to direct transmission of pasteurellosis is high when herds are not guarded nor enclosed, whereas exposure to indirect transmission of brucellosis is increased on epidemiological dangerous points such as salt deposits. Our preliminary results need further investigation, but they underline the importance of both herd management and pathogen transmission mode when the aim is to reduce the risk of contamination of wild populations by a pathogen associated with domestic pathogens.

Altitude↗
PubMed2003

A climate-based model predicts the spatial distribution of the Lyme disease vector Ixodes scapularis in the United States.

An understanding of the spatial distribution of the black-legged tick, Ixodes scapularis, is a fundamental component in assessing human risk for Lyme disease in much of the United States. Although a county-level vector distribution map exists for the United States, its accuracy is limited by arbitrary categories of its reported presence. It is unknown whether reported positive areas can support established populations and whether negative areas are suitable for established populations. The steadily increasing range of I. scapularis in the United States suggests that all suitable habitats are not currently occupied. Therefore, we developed a spatially predictive logistic model for I. scapularis in the 48 conterminous states to improve the previous vector distribution map. We used ground-observed environmental data to predict the probability of established I. scapularis populations. The autologistic analysis showed that maximum, minimum, and mean temperatures as well as vapor pressure significantly contribute to population maintenance with an accuracy of 95% (p < 0.0001). A cutoff probability for habitat suitability was assessed by sensitivity analysis and was used to reclassify the previous distribution map. The spatially modeled relationship between I. scapularis presence and large-scale environmental data provides a robust suitability model that reveals essential environmental determinants of habitat suitability, predicts emerging areas of Lyme disease risk, and generates the future pattern of I. scapularis across the United States.

Animals↗
PubMed2001

Pollution-induced community tolerance (PICT) and seasonal variations in the sensitivity of phytoplankton to atrazine in nanocosms.

Algae communities exposed to a herbicide like atrazine (PS II inhibitor) are expected to be selected and to be more tolerant to the herbicide than unexposed communities (pollution-induced community tolerance, PICT). The PICT may be an ecotoxicological tool for detecting this selective action of chronic pollution, and this method has been applied to several toxicants in experimental systems and in field studies. But the detection of PICT with PS II inhibitors has sometimes been variable. This work was done to study the long-term effects of exposure to atrazine (10 microg/l) and the PICT responses of phytoplankton communities in repeated outdoor nanocosms. Phytoplankton communities were sampled in Lake Geneva at different periods of the year and the effects of atrazine were analysed by studying community structure, biomass and primary production, and by measuring tolerance to atrazine in a short-term physiological test based on 14C incorporation. We find that PICT is a sensitive method for measuring effects. Even atrazine concentrations causing little restructuring induced tolerance in most of our experiments. But the short- and long-term responses of phytoplankton to atrazine varied between experiments, probably due to the initial compositions of the communities and environmental factors associated with seasonal parameters. The selection and detection steps of PICT to atrazine thus vary greatly with environmental conditions and the physiological adaptations of algae to the herbicide. To monitor risk assessment in aquatic systems, PICT studies applied to algae, must be investigated in the light of seasonal contaminations and seasonal events and successions.

Adaptation, Physiological↗
PubMed1993

Reduced abundance of Ixodes scapularis (Acari: Ixodidae) and Lyme disease risk by deer exclusion.

The effect of deer exclosures upon the numbers of immature Ixodes scapularis Say, the vector of Lyme disease in the eastern United States, was examined at five sites in Westchester County, NY. Study areas ranged in size from 6 to 101 ha where deer had been excluded for a period of 25 yr by > 2.4-m-high fencing that surrounded each site. A total area of 40,506 m2 was drag-sampled during the study to measure tick abundance. Nymphal densities (ticks per 1,000 m2) averaged 4.6 (range, 1.3-9.6) inside exclosures and 27.7 (range, 7.3-79.4) outside. Larval densities averaged 36.7 (range, 1.2-132.1) inside exclosures and 354.4 (range, 7.5-914.5) outside. Comparisons between exclosure sites and outside areas immediately adjacent to the exclosure fence, where deer had unrestricted access, revealed that exclosures had 83% fewer host-seeking nymphs and 90% fewer host-seeking larvae. Tick numbers inside exclosures did not always decline with increasing distance from the fence. There was no significant difference in the rate of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner infection for host-seeking ticks collected inside (20%, n = 50) exclosures compared with ticks collected outside (26%, n = 50) exclosures. Deer fencing may provide a means of significantly reducing the abundance of I. scapularis and the risk of Lyme disease in relatively large areas without the need to reduce or eliminate the deer population.

Animals↗
PubMed2002

Ecological effects of an anionic C12-15 AE-3S alkylethoxysulfate surfactant in outdoor stream mesocosms.

The ecological assessment of a C12-15 AE-3S linear alkylethoxysulfate (AES) anionic surfactant to invertebrates, fish, periphyton, and an aquatic macrophyte was conducted in a 30-d outdoor stream mesocosm study with five replicated concentrations and controls. Alkylethoxysulfate structural integrity and exposure concentrations were maintained during the 30-d treatment period, with average measured concentrations of 0.7, 1.27, 2.2, 4.31, and 10.18 mg/L. No effects were observed on the aquatic macrophyte Myriophyllum aquaticum at the highest concentration tested. A sevenfold increase in periphyton biomass at 10.18 mg/L was observed relative to controls primarily because of increases in density of the filamentous alga Mougeotia sp. Densities of the invertebrates Annelida (Stylaria), Amphipoda, Copepoda, Trichoptera (Hydropsychidae), Cladocera, and Diptera (Chironomidae) significantly decreased in streams treated with AES at 10.18 mg/L. Densities of drifting invertebrates were not observed to be affected at any concentration tested. Reproduction of Pimephales promelas significantly decreased at 1.27 mg/L and growth of juvenile Lepomis macrochirus was significantly affected at 4.31 mg/L. Multivariate cluster analysis and nonmetric multidimensional scaling ordination showed distinct structural effects on the invertebrate communities in the streams treated with AES at 10.18 mg/ L compared to the control and streams treated at < 10.18 mg/L through the 30-d treatment. Convergence of the communities treated at 10.18 mg/L toward control communities in the ordination suggests recovery in these communities after termination of surfactant treatment. The results from this study support an ecosystem value of > 2.0 mg/L, and indicate that the conservative Dutch risk assessment for AESs has at least a fivefold margin of safety.

Animals↗
PubMed2003

The fate, distribution, and toxicity of lindane in tests with Chironomus riparius: effects of bioturbation and sediment organic matter content.

In this laboratory study, we address the effect of Chironomus bioturbation (0, 2,000, 6,000, and 18,000 ind/m2) and sediment organic matter content (10, 20, and 40%) on the fate, distribution, and bioavailability of 14C-lindane under standardized conditions in toxicity tests with artificial sediment. The results show that both Chironomus burrowing activity and sediment organic matter strongly modify test conditions. Larval mortality and development were inversely related with Chironomus densities and lindane concentration. Sediment organic matter content affected larval development rates but not mortality. Partitioning of lindane between the sediment, overlying water, and interstitial water was affected negatively by Chironomus larval densities: however, sediment partitioning was positively affected by sediment organic matter content. Bioturbation by Chironomus resulted in a remobilization of particle-associated lindane to the interstitial and overlying water, implying an increase in the bioavailability of the test compound. Strong positive relationships were found between Chironomus densities and lindane concentrations in interstitial water. The presence of Chironomus also resulted in lower label recovery. Label recovery on sediment particles ranged from 49 to 61% of initially added label in microcosms without Chironomus, from 41 to 56% at low larval densities, and from 15 to 50% at high larval densities. These results show that large discrepancies may exist between nominal test concentrations (from test compound additions) and true exposure concentrations even under standardized test conditions, which can introduce a relatively large error term in risk assessments. Calculations show that volatilization may be a quantitatively important sink for test compounds.

Animals↗
PubMedDate not supplied

Social variables and suicide in the population of Genoa, Italy.

A study of the relationship between sociodemographic conditions and suicidal risk was conducted on 377 cases of suicide committed in Genoa between 1985 and 1988. We used random subjects among Genoa residents as a control group. Data obtained were analyzed by means of an unconditional logistic regression model. The most interesting result of the study is the considerable suicide risk found among unmarried people.

Adult↗
PubMed2005

Extensive immigration from compensatory hatchery releases into wild Atlantic salmon population in the Baltic sea: spatio-temporal analysis over 18 years.

Genetic homogenization has been recognized as a serious threat in an increasing number of species, including many salmonid fishes. We assessed the rate and impact of immigration from the main hatchery stocks of Atlantic salmon in the Gulf of Bothnia into one of the largest wild salmon populations in the Baltic Sea, the River Vindelälven, within a temporal framework of 18 years (from 1985-2003). We provide genetic evidence based on mtDNA and microsatellite markers, using mixed-stock analysis, that a large proportion (66%) of fin-damaged spawners (n=181) caught in the Ume/Vindelälven during 1997-2003 originated from the hatcheries in the Rivers Angermanälven, Luleälven and Ljusnan. The maximum-likelihood estimate of immigration rate from these hatcheries into the wild Vindelälven population was 0.068 (95% CI 0.021-0.128) over the studied time period (1985-2003) and reached up to a quarter (m=0.249, 95% CI 0.106-0.419) of the total population during 1993-2000. This resulted in significant (P<0.01) genetic homogenization trend between the wild Vindelälven population and hatchery stocks of the Angermanälven and Luleälven. Our results demonstrate extensive straying from geographically distant hatchery releases into wild salmon population and emphasize the genetic risks associated with current large-scale stocking practices in the Baltic Sea.

Animals↗
PubMed2006

Biological control agents elevate hantavirus by subsidizing deer mouse populations.

Biological control of exotic invasive plants using exotic insects is practiced under the assumption that biological control agents are safe if they do not directly attack non-target species. We tested this assumption by evaluating the potential for two host-specific biological control agents (Urophora spp.), widely established in North America for spotted knapweed (Centaurea maculosa) control, to indirectly elevate Sin Nombre hantavirus by providing food subsidies to populations of deer mice (Peromyscus maniculatus), the primary reservoir for the virus. We show that seropositive deer mice (mice testing positive for hantavirus) were over three times more abundant in the presence of the biocontrol food subsidy. Elevating densities of seropositive mice may increase risk of hantavirus infection in humans and significantly alter hantavirus ecology. Host specificity alone does not ensure safe biological control. To minimize indirect risks to non-target species, biological control agents must suppress pest populations enough to reduce their own numbers.

Animals↗
PubMed2006

Field evaluation of an avian risk assessment model.

We conducted two laboratory subacute dietary toxicity tests and one outdoor subacute dietary toxicity test to determine the effectiveness of the U.S. Environmental Protection Agency's deterministic risk assessment model for evaluating the potential of adverse effects to birds in the field. We tested technical-grade diazinon and its D.Z.N 50W (50% diazinon active ingredient wettable powder) formulation on Canada goose (Branta canadensis) goslings. Brain acetylcholinesterase activity was measured, and the feathers and skin, feet, and gastrointestinal contents were analyzed for diazinon residues. The dose-response curves showed that diazinon was significantly more toxic to goslings in the outdoor test than in the laboratory tests. The deterministic risk assessment method identified the potential for risk to birds in general, but the factors associated with extrapolating from the laboratory to the field, and from the laboratory test species to other species, resulted in the underestimation of risk to the goslings. The present study indicates that laboratory-based risk quotients should be interpreted with caution.

Acetylesterase↗
PubMed2001

Comparison of different life-cycle impact assessment methods for aquatic ecotoxicity.

Human and ecotoxicity impact categories are problematic to quantify within life-cycle impact assessment (LCIA) because their local scope makes them difficult to aggregate with the traditional global-impact categories used in life-cycle assessment (LCA). For being able to assess local impacts such as toxicity, LCIA developers increasingly include fate modeling into LCA. This article follows this development by comparing different LCIA methods for aquatic ecotoxicology and by investigating the importance of fate within LCIA, the necessity of considering freshwater and seawater compartments separately, and the key degradation and intermedia transfer processes involved. The methods are compared by assessing an example study of domestic clothes washing in former West Germany. Four LCIA methods are selected and applied to four substances emitted during the washing process. The conclusion is that the consideration of environmental fate does matter and that aquatic ecotoxic impacts can differ significantly for the same substance in freshwater and in marine ecosystems. The way (bio)degradation, photolysis, volatilization, and transfer from agricultural soils are considered plays an important role as do the system boundaries chosen. This means that the LCIA methodology should remain flexible so that appropriate methods can be chosen for different applications. Fate models being developed in the environmental risk assessment of chemicals can contribute to the further improvement of LCIA methods.

Agriculture↗
PubMed2026

Dual &#x3b2;-lactam therapy against high-risk Pseudomonas aeruginosa isolates: a dynamic in-vitro infection model study integrating population genomics with quantitative systems pharmacology modelling and simulations.

BACKGROUND: Pseudomonas aeruginosa has an extraordinary capacity for resistance emergence during treatment, even with newer antipseudomonals. There is a gap in understanding how resistance mechanisms affect the time-course of bacterial response to these newer agents. Traditional approaches for predicting pathogen response to an antibiotic do not apply to combination therapy. We aimed to develop a modelling framework to predict treatment response based on resistome information, using isolates of the worldwide-disseminated high-risk clone sequence type (ST) 235 and &#x3b2;-lactam antibiotics as the example. METHODS: In this hollow-fibre in-vitro infection study, we used three extensively drug-resistant ST235 clinical isolates from the national collection of the Clinical Microbiology Department of the Hospital Son Espases (Palma de Mallorca, Spain) that were hospital-acquired, were isolated following routine microbiological procedures from different patients between 2017 and 2022, were susceptible to ceftolozane-tazobactam, and had different levels of meropenem resistance. The selected isolates (ST235-05, ST235-09, and ST235-10) showed classical &#x3b2;-lactam resistance mechanisms pre-treatment. The isolates were investigated in 240-h dynamic hollow-fibre in-vitro infection models (HFIMs). The studies exposed the isolates to pharmacokinetic profiles of ceftolozane-tazobactam (simulating 1 g of ceftolozane and 0&#xb7;5 g of tazobactam as a 3-h infusion every 8 h) and meropenem (simulating 6 g per day continuous infusion) as observed in hospitalised patients, as monotherapy and in combination. Treatment response was assessed through the quantification of the time-courses of viable total and resistant bacteria. Whole-genome sequencing identified the mechanisms of emerging resistance. A quantitative systems pharmacology (QSP) approach was used to model total and resistant bacterial counts and corresponding pharmacokinetic data from the HFIM. Monte Carlo simulations were used to predict treatment responses in 1000 virtual infected patients treated with ceftolozane-tazobactam and meropenem as monotherapies or in combination over 10 days. FINDINGS: In the HFIMs, each antibiotic alone amplified resistance by approximately 48 h for all isolates; that is, monotherapies resulted in a higher concentration of resistant bacteria compared with the control treatment at the respective time, except ceftolozane-tazobactam against ST235-10. Combination of ceftolozane-tazobactam and meropenem was synergistic (bacterial counts &#x2265;2 log10 colony forming units [CFU] per mL lower than the best performing monotherapy and initial inoculum) against all isolates and suppressed resistance. Against ST235-10, ceftolozane-tazobactam monotherapy reduced counts to less than 1 log10 CFU per mL from 192 h onwards, whereas the combination reached less than 1 log10 CFU per mL by 24 h. Across strains, population genomics confirmed monotherapy failures were associated with emerging resistance mechanisms (ceftolozane-tazobactam: ampC &#x3a9;-loop mutations; meropenem: ftsl mutation). The developed QSP model incorporated baseline resistance mechanisms and those emerging in resistant mutant subpopulations. The model explained and predicted the monotherapy failures involving amplification of these subpopulations, and synergistic killing and resistance suppression by the combination. Simulations using the model predicted bacterial regrowth above the initial inoculum for more than 90% of patients after 0 to approximately 3 days for meropenem monotherapy across all strains and for ceftolozane-tazobactam monotherapy against ST235-05 and ST235-09. For ceftolozane-tazobactam monotherapy against ST235-10, regrowth was predicted for approximately 30% of patients. In contrast, the simulations predicted sustained bacterial killing of at least 2 log10 CFU per mL compared with the initial inoculum by the combination for more than 89% of patients across all strains. INTERPRETATION: To our knowledge, this model is the first to characterise and predict the time-course of responses of clinical isolates to antibiotics only by the resistance mechanisms present and their complex interplay, representing a step towards pathogen-specific, personalised medicine. FUNDING: Australian National Health and Medical Research Council.

Pseudomonas aeruginosa↗
PubMed1993

[Determinants of mortality].

"In this article determinants of mortality [in the Netherlands] are studied.... The main results are the following: For all ages women have lower mortality risks than men.... Married people live longer than those who are not. However, the cause is not certain.... In large cities mortality rates are higher than in small towns (especially due to diseases of the lungs and to narcotics, alcohol and violent causes of death). People with a high socio-economic status have lower mortality risks than those with a low status." (SUMMARY IN ENG)

Alcohol Drinking↗
PubMed2005

[Epidemiology of Alzheimer's disease].

Because of global ageing of the population, the occurrence of Alzheimer's disease (AD) cases is increasing dramatically and AD is becoming a major public health preoccupation. By the year 2020, the World Health Organisation predicts that there will be almost 29 millions demented people throughout the world, two third of them being AD cases. This dramatic perspective could only be modified with new curative treatments or prevention. These last years, there is increasing evidence from epidemiological studies for the role of vascular risk factors in the aetiology of AD among which hypertension, type 2 diabetes, or high cholesterol. These potentially modifiable risk factors raise hope for prevention of Alzheimer's disease.

Aged↗
PubMed2006

Risk factors for childhood diarrhea incidence: dynamic analysis of a longitudinal study.

BACKGROUND: Several longitudinal studies have investigated factors associated with childhood diarrhea in developing countries. However, most studies have neglected important dynamic features of the longitudinal design and hierarchical interrelationships among the potential risk factors. METHODS: We conducted a longitudinal study of 902 children, age 0 to 36 months at baseline, in a large urban center in northeastern Brazil. Diarrhea data were collected by following children from October 2000 until January 2002 with biweekly home visits. We used a dynamic time-to-event analysis to account for several longitudinal features. We applied an effect-decomposition strategy to quantify direct and indirect effects of risk factors grouped in different blocks. RESULTS: Child's age and an autoregressive effect of past diarrhea episodes explained some of the decline of diarrhea incidence observed throughout the study (from more than 14 episodes to 2 episodes per child-year), a phenomenon already observed but not explained in other longitudinal diarrhea studies. We identified the following major diarrhea determinants: low socioeconomic status, poor sanitation conditions, presence of intestinal parasites, and absence of prenatal examination. The effect of socioeconomic status was mediated mostly by living and sanitation conditions. CONCLUSION: Our study shows important advantages of applying a dynamic analysis approach to longitudinal observational studies of diarrhea or other acute diseases and highlights the complex interrelationships of diarrhea determinants. Our results confirm the importance of sanitation as a major determinant of child health in urban settings of developing countries.

Brazil↗
PubMed2002

Fate and effects of the triazinone herbicide metribuzin in experimental pond mesocosms.

Metribuzin is a triazinone herbicide that is widely used for the control of grasses and broad-leaved weeds in soybeans, sugarcane, and numerous other crops. Metribuzin is highly toxic to freshwater macrophytes and algae under laboratory conditions (median plant EC(50) = 31 microg/L; n = 11 species) but has not been studied under controlled outdoor conditions. We conducted a 6-week study to examine the aquatic fate and effects of metribuzin in 0.1-ha outdoor aquatic mesocosms. Mesocosms (n = 2 per treatment) were treated with metribuzin at one of five concentrations: 0, 9, 19, 38, or 75 microg/L. Concentrations were selected to bracket known laboratory effect concentrations and to reflect calculated edge-of-field concentrations. The dissipation half-life of metribuzin in water was 5 days. Metribuzin had no statistically significant effects on water quality, periphyton biomass, macrophyte biomass, macrophyte species composition, fish survival, or fish growth at treatment levels ranging up to and including 75 microg/L. Although metribuzin is highly toxic to freshwater macrophytes and algae under laboratory conditions, it poses little risk to nontarget aquatic plants due to the short aqueous dissipation half-life. The findings also demonstrate that current herbicide risk assessment procedures used in the registration process could benefit from empirical assessments of the fate of chemicals under realistic environmental conditions.

Animals↗
PubMed1996

Sex and time trends in cardiovascular disease incidence and mortality: the Framingham Heart Study, 1950-1989.

Variations in cardiovascular disease mortality between sexes, over time, and across regions point to population differences in the biologic, behavioral, and environmental factors influencing cardiovascular health. The authors examined 20-year trends in risk factors, incidence, and mortality among women and men in Framingham, Massachusetts, who were members of the Framingham Heart Study and aged 50-59 years in 1950, 1960, and 1970. The incidence declined 21% between the female cohorts (p < 0.01 for trend) with the greatest decline occurring between the 1950 and 1960 cohorts. The 20-year incidence declined only 6% between the male cohorts despite an 18% decline (p < 0.05 for trend) during the first 10 years of follow-up. Cardiovascular disease mortality declined 59% between the female cohorts and 53% between the male cohorts (both p < 0.001 for trend). The largest mortality declines occurred between the 1950 and 1960 female cohorts during the second 10 years of follow-up and between the 1960 and 1970 male cohorts during both follow-up periods. Obesity, hypercholesterolemia, and high blood pressure were significantly lower at baseline and 10 years later in the 1970 female cohort compared with the 1950 cohort (all p < 0.001). Smoking and high blood pressure were significantly lower at baseline and 10 years later in the 1970 male cohort compared with the 1950 cohort (both p < 0.001). More than half of the 51% decline in coronary heart disease mortality observed in women between 1950 and 1989 and one third to one half of the 44% decline observed in men could be attributed to improvements in risk factors in the 1970 cohorts.

Adult↗