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Disease Incidence (disease + incidence)

Distribution by Scientific Domains

Life Sciences	50%
Medical Sciences	35%
Chemistry	7%
2 Other Domains	8%

Distribution within Life Sciences

Plant Science	52%
Plant Pathology	14%

Selected Abstracts

Dementia and Alzheimer's Disease Incidence in Relationship to Cardiovascular Disease in the Cardiovascular Health Study Cohort

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2005
Anne B. Newman MD
Objectives: To determine whether coronary artery disease, peripheral arterial disease (PAD), or noninvasive markers of cardiovascular disease (CVD) predict the onset of dementia and Alzheimer's disease (AD). Design: Longitudinal cohort study. Setting: Four U.S. communities. Participants: Men and women (N=3,602) with a brain magnetic resonance imaging (MRI) scan but no dementia were followed for 5.4 years. Participants with stroke were excluded. Measurements: Neurologists and psychiatrists classified incident cases of dementia and subtype using neuropsychological tests, examination, medical records and informant interviews. CVD was defined at the time of the MRI scan. Noninvasive tests of CVD were assessed within 1 year of the MRI. Apolipoprotein E allele status, age, race, sex, education, Mini-Mental State Examination score, and income were assessed as potential confounders. Results: The incidence of dementia was higher in those with prevalent CVD, particularly in the subgroup with PAD. The rate of AD was 34.4 per 1,000 person-years for those with a history of CVD, versus 22.2 per 1,000 person-years without a history of CVD (adjusted hazard ratio (HR)=1.3, 95% confidence interval (CI)=1.0,1.7). Rates of AD were highest in those with PAD (57.4 vs 23.7 per 100 person-years, adjusted HR=2.4, 95% CI=1.4,4.2). Results were similar with further exclusion of those with vascular dementia from the AD group. A gradient of increasing risk was noted with the extent of vascular disease. Conclusion: Older adults with CVD other than stroke had a higher risk of dementia and AD than did those without CVD. The risk was highest in people with PAD, suggesting that extensive peripheral atherosclerosis is a risk factor for AD. [source]

Geographic Variation in End-Stage Renal Disease Incidence and Access to Deceased Donor Kidney Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4p2 2010
A. K. Mathur
The effect of demand for kidney transplantation, measured by end-stage renal disease (ESRD) incidence, on access to transplantation is unknown. Using data from the U.S. Census Bureau, Centers for Medicare & Medicaid Services (CMS) and the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients (OPTN/SRTR) from 2000 to 2008, we performed donation service area (DSA) and patient-level regression analyses to assess the effect of ESRD incidence on access to the kidney waiting list and deceased donor kidney transplantation. In DSAs, ESRD incidence increased with greater density of high ESRD incidence racial groups (African Americans and Native Americans). Wait-list and transplant rates were relatively lower in high ESRD incidence DSAs, but wait-list rates were not drastically affected by ESRD incidence at the patient level. Compared to low ESRD areas, high ESRD areas were associated with lower adjusted transplant rates among all ESRD patients (RR 0.68, 95% CI 0.66,0.70). Patients living in medium and high ESRD areas had lower transplant rates from the waiting list compared to those in low ESRD areas (medium: RR 0.68, 95% CI 0.66,0.69; high: RR 0.63, 95% CI 0.61,0.65). Geographic variation in access to kidney transplant is in part mediated by local ESRD incidence, which has implications for allocation policy development. [source]

EFFECT OF HOT WATER IMMERSION ON PEEL COLOR OF PEARS AND ON WHITE ROT CAUSED BY BOTRYOSPHAERIA BERENGERIANA

JOURNAL OF FOOD QUALITY, Issue 5 2003
MUHAMMAD IMRAN AL-HAQ
After HWI at 40, 45, 48, 50, 52 and 54C for varying immersion periods, the pears were held at 20C, , 90% RH (simulated retail conditions). The peel color (L*, a*, b*) was determined before and after HWI treatment. The dominant role of L* suggested that peel darkening was the major factor in color change of the HWI treated pears. The L* value of 54 was judged as the border line for acceptability and less than 51 resulted in browning. Similarly the critical points for a*, b*, chroma, hue and ,E* were found to be ,6, 34, 35, 100, and 8, respectively. Disease incidence recorded 7 days after treatment revealed that High Temperature Short Time (HTST) treatment of 54C for 3 min reduced incidence about 85% with good retention of color. Both temperature and immersion period are to be carefully selected to prolong shelf-life and retain the peel color quality of ,La-France'pears. [source]

Present and past old-growth forests of the Lake Tahoe Basin, Sierra Nevada, US

JOURNAL OF VEGETATION SCIENCE, Issue 4 2002
M. Barbour
Hickman (1993) for vascular plants; Furniss & Carolin (1977) for bark beetles; Hansen & Lewis (1997) for pathogens Abstract. We described 38 relictual old-growth stands , with data on the mortality, regeneration, floristic richness, fuel load and disease incidence in our study area in the Tahoe Basin of California and Nevada. The stands are within the lower and upper montane zones (1900,2400 m a.s.l.) and they are rare, occupying < 2% of the land in the Basin's watershed. Correlation matrices and ANOVAs of forest types and conifer species with environmental gradients revealed significant relationships with elevation, distance east of the Sierran crest, slope aspect, annual precipitation, date of complete snow melt, litter depth and degree of soil profile development. Pathogens, parasites and wood-boring insects were present on 23% of living trees; 16% of all trees were dead. We compared these stands to a reconstruction of pre-contact Basin forests and to ecologically analogous old-growth forests of Baja California that have never experienced fire suppression management. Currently, overstorey trees (> 180 yr old) in the Basin stands have ca. 33% cover, 54 m2.ha -1 basal area and 107 individuals.ha -1, values very similar to reconstructions of pre-contact Basin forests and to modern Baja California forests. Understorey trees (60,180 yr old), however, are several times more dense than historic levels and species composition is strongly dominated by A. concolor, regardless of the overstorey composition. The ratio of Pinus: Abies has increased , and the age structure of extant stands predicts that it will continue to increase , from approximately 1:1 in pre-contact time to 1:7 within the next century. Disease incidence and mortality in Baja forests were lower. Although we quantitatively defined current Basin old-growth forests , in terms of stand structure , we realize that our definition will differ from that of both past and future old-growth forests unless management protocols are changed. [source]

Allelochemical tricin in rice hull and its aurone isomer against rice seedling rot disease

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2010
Chui-Hua Kong
Abstract BACKGROUND: One promising area of rice disease management is the potential of exploiting biological control agents. Rice seedling rot disease caused by soil-borne pathogenic fungi has become a dominant disease problem because of greater use of direct seeding. Rice hull has been potentially used to control paddy weeds, but little information is available on rice disease. This study was conducted to investigate the relationships between disease incidence and soil amended with tricin-releasing rice hull, and to assess fungicidal activity of tricin and its synthesised aurone isomer, with an attempt to develop an allelochemical-based fungicide against rice seedling rot disease. RESULTS: Tricin was detected in all hulls of 12 rice cultivars tested, but its contents in rice hulls varied greatly with the cultivar and genotype. Tricin in rice hulls was released into the soil once amended. Disease incidence was significantly reduced by soil amended with rice hull. Tricin-rich rice hull amendment greatly suppressed soil-borne pathogenic fungi Fusarium oxysporum Schlecht. and Rhizoctonia solani Kühn which cause rice seedling rot disease. In attempting to obtain enough tricin for further experiments, the aurone isomer (5,7,4,-trihydroxy-3,,5,-dimethoxyaurone) of tricin rather than tricin itself was unexpectedly synthesised. This aurone isomer had much stronger fungicidal activity on both F. oxysporum and R. solani than tricin itself. CONCLUSION: Soil amended with tricin-rich rice hull was associated with reduced risk of developing seedling rot disease. The tricin isomer, aurone, is more effective against rice seedling rot disease than tricin itself, making it an ideal lead compound for new fungicide discovery. Copyright © 2010 Society of Chemical Industry [source]

Conidial dispersal by Alternaria brassicicola on Chinese cabbage (Brassica pekinensis) in the field and under simulated conditions

PLANT PATHOLOGY, Issue 5 2003
L. Y. Chen
This study investigated conidial dispersal in the field, and effects of simulated wind and rain on the dispersal of A. brassicicola on Chinese cabbage (Brassica pekinensis). Spores were sampled using a Burkard volumetric spore sampler and rotorod samplers in a Chinese cabbage crop. Disease incidence in the field was well fitted by a Gompertz curve with an adjusted r2 of >0·99. Conidia of A. brassicicola were trapped in the field throughout the growing season. Peaks of high spore concentrations were usually associated with dry days, shortly after rain, high temperature or high wind speed. Diurnal periodicity of spore dispersal showed a peak of conidia trapped around 10·00 h. The number of conidia trapped at a height of 25 cm above ground level was greater than that at 50, 75 and 100 cm. Conidial dispersal was also studied under simulated conditions in a wind tunnel and a rain simulator. Generalized linear models were used to model these data. The number of conidia caught increased significantly at higher wind speeds and at higher rain intensities. Under simulated wind conditions, the number of conidia dispersed from source plants with wet leaves was only 22% of that for plants with dry leaves. Linear relationships were found between the number of conidia caught and the degree of infection of trap plants. [source]

Variation in the response of melon genotypes to Fusarium oxysporum f.sp. melonis race 1 determined by inoculation tests and molecular markers

PLANT PATHOLOGY, Issue 2 2003
Y. Burger
Screening of genotypes of melon (Cucumis melo) for resistance to wilt caused by Fusarium oxysporum f.sp. melonis is often characterized by wide variability in their responses to inoculation, even under carefully controlled conditions. The variability at the seedling stage of 17 genotypes susceptible to race 1 was examined in growth-chamber experiments. Disease incidence varied from 0 to 100% in a genotype-dependent manner. Using four combinations of light (60 and 90 µE m,2 s,1) and temperatures of (27 and 31°C), only light intensity showed a statistically significant effect. Marker-assisted selection for fusarium resistance breeding using cleaved amplified polymorphic sequence (CAPS) and sequence-characterized amplified region (SCAR) markers were compared using a single set of genotypes that included 24 melon accessions and breeding lines whose genotype regarding the Fom-2 gene was well characterized. The practical value of the markers for discriminating a range of genotypes and clarifying the scoring of phenotypes was also tested using a segregating breeding population which showed codominant SCAR markers to be useful in marker-assisted selection. [source]

The chemokine receptor antagonist, TAK-779, decreased experimental autoimmune encephalomyelitis by reducing inflammatory cell migration into the central nervous system, without affecting T cell function

BRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2009
Jia Ni
Background and purpose:, The C,C chemokine receptor CCR5, and the C,X,C chemokine receptor CXCR3 are involved in the regulation of T cell-mediated immune responses, and in the migration and activation of these cells. To determine whether blockade of these chemokine receptors modulated inflammatory responses in the central nervous sytem (CNS), we investigated the effect of a non-peptide chemokine receptor antagonist, TAK-779, in mice with experimental autoimmune encephalomyelitis (EAE). Experimental approach:, EAE was induced by immunization of C57BL/6 mice with myelin oligodendrocyte glycoprotein (MOG) 35,55. TAK-779 was injected s.c. once a day after immunization. Disease incidence and severity (over 3 weeks) were monitored by histopathological evaluation and FACS assay of inflammatory cells infiltrating into the spinal cord, polymerase chain reaction quantification of mRNA expression, assay of T cell proliferation, by [3H]-thymidine incorporation and cytokine production by enzyme-linked immunosorbent assay. Key results:, Treatment with TAK-779 reduced incidence and severity of EAE. It strongly inhibited migration of CXCR3/CCR5 bearing CD4+, CD8+ and CD11b+ leukocytes to the CNS. TAK-779 did not reduce proliferation of anti-MOG T cells, the production of IFN-, by T cells or CXCR3 expression on T cells. In addition, TAK-779 did not affect production of IL-12 by antigen-presenting cells, CCR5 induction on T cells and the potential of MOG-specific T cells to transfer EAE. Conclusions and implications:, TAK-779 restricted the development of MOG-induced EAE. This effect involved reduced migration of inflammatory cells into the CNS without affecting responses of anti-MOG T cells or the ability of MOG-specific T cells to transfer EAE. [source]

Secular trends, disease maps and ecological analyses of the incidence of childhood onset Type 1 diabetes in Northern Ireland, 1989,2003

DIABETIC MEDICINE, Issue 3 2007
C. R. Cardwell
Abstract Aims To investigate secular trends in the incidence of Type 1 diabetes in Northern Ireland over the period 1989,2003. To highlight geographical variations in the incidence of Type 1 diabetes by producing disease maps and to compare incidence rates by relevant area characteristics. Methods New cases of Type 1 diabetes in children aged 0,14 years in Northern Ireland were prospectively registered from 1989 to 2003. Standardized incidence rates were calculated and secular trends investigated. Bayesian methodology was used to produce maps of disease incidence using small geographical areas (582 electoral wards). Ecological analyses were conducted using Poisson regression to investigate incidence rates by area characteristics at a finer geographical subdivision (5022 census output areas). Results In Northern Ireland during 1989,2003, there were 1433 new cases, giving a directly standardized incidence rate of 24.7 per 100 000 person-years. This incidence rate increased by a mean of 4.2% per annum. Disease maps highlighted higher incidence rates in the predominately rural north-east of the province and lower incidence rates in the urban areas around Belfast in the east and Derry in the north-west of the province. Ecological analysis identified higher incidence in rural areas (P < 0.001), areas with low migration rates (P = 0.002), affluent areas (P < 0.0001), sparsely populated areas (P = 0.0001) and remote areas (P = 0.005). Conclusions In Northern Ireland the incidence of Type 1 diabetes is increasing. The observed higher incidence in rural, affluent, sparsely populated and remote areas may reflect a reduced or delayed exposure to infections in these areas. [source]

Vector within-host feeding preference mediates transmission of a heterogeneously distributed pathogen

ECOLOGICAL ENTOMOLOGY, Issue 3 2010
MATTHEW P. DAUGHERTY
1. Ecological theory predicts that vector preference for certain host species or discrimination between infected versus uninfected hosts impacts disease incidence. However, little information exists on the extent to which vector within-host feeding preference mediates transmission. This may be particularly important for plant pathogens, such as sharpshooter transmission of the bacterium Xylella fastidiosa, which are distributed irregularly throughout hosts. 2. We documented the within-host distribution of two vector species that differ in transmission efficiency, the leafhoppers Draeculacephala minerva and Graphocephala atropunctata, and which are free to move throughout entirely caged alfalfa plants. The more efficient vector D. minerva fed preferentially at the base of the plant near the soil surface, whereas the less efficient G. atropunctata preferred overwhelming the top of the plant. 3. Next we documented X. fastidiosa heterogeneity in mechanically inoculated plants. Infection rates were up to 50% higher and mean bacterial population densities were 100-fold higher near the plant base than at the top or in the taproot. 4. Finally, we estimated transmission efficiency of the two leafhoppers when they were confined at either the base or top of inoculated alfalfa plants. Both vectors were inefficient when confined at the top of infected plants and were 20,60% more efficient when confined at the plant base. 5. These results show that vector transmission efficiency is determined by the interaction between leafhopper within-plant feeding behaviour and pathogen within-plant distribution. Fine-scale vector and pathogen overlap is likely to be a requirement generally for efficient transmission of vector-borne pathogens. [source]

Interference of quorum sensing in Pseudomonas syringae by bacterial epiphytes that limit iron availability

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2010
Glenn F. J. Dulla
Summary Leaf surfaces harbour bacterial epiphytes that are capable of influencing the quorum sensing (QS) system, density determination through detection of diffusible signal molecules, of the plant-pathogen Pseudomonas syringae pv. syringae (Pss) which controls expression of extracellular polysaccharide production, motility and other factors contributing to virulence to plants. Approximately 11% of the bacterial epiphytes recovered from a variety of plants produced a diffusible factor capable of inhibiting the QS system of Pss as indicated by suppression of ahlI. Blockage of QS by these interfering strains correlated strongly with their ability to limit iron availability to Pss. A direct relationship between the ability of isogenic Escherichia coli strains to sequester iron via their production of different siderophores and their ability to suppress QS in Pss was also observed. Quorum sensing induction was inversely related to iron availability in culture media supplemented with iron chelators or with FeCl3. Co-inoculation of interfering strains with Pss onto leaves increased the number of resultant disease lesions over twofold compared with that on plants inoculated with Pss alone. Transposon-generated mutants of interfering strains in which QS inhibition was blocked did not increase disease when co-inoculated with Pss. Increased disease incidence was also not observed when a non-motile mutant of Pss was co-inoculated onto plants with QS interfering bacteria suggesting that these strains enhanced the motility of Pss in an iron-dependent manner, leading to an apparent increase in virulence of this pathogen. Considerable cross-talk mediated by iron scavenging apparently occurs on plants, thereby altering the behaviour of bacteria such as Pss that exhibit important QS-dependent traits in this habitat. [source]

Resistance of potato cultivars to Synchytrium endobioticum in field and laboratory tests, risk of secondary infection, and implications for phytosanitary regulations

EPPO BULLETIN, Issue 1 2005
R. P. Baayen
Laboratory (Spieckermann) tests, pot tests and field tests provided concordant evidence for the partial nature of resistance of potatoes to pathotypes 1 (D1) and 6 (O1) of Synchytrium endobioticum. Susceptible potato cultivars produced large warts (> 16 mm in diameter) in Spieckermann tests and had low field resistance levels (1,6). Field-resistant cultivars (levels 7,9) produced small warts or no warts at all in Spieckermann and field tests. In pot tests, at low inoculum levels (1 sporangium per 25 g soil) susceptible cultivars still developed warts, whereas field-resistant ones did not develop any warts below 25 sporangia per g soil. Above 35 sporangia per g soil, 100% disease incidence was observed in susceptible cultivars but only minimal wart development in field-resistant ones. Tests with continuous cultivation of potato cultivars in infected soil during three consecutive years showed that field-resistant cultivars will not support build-up of inoculum in soil. It is concluded that field-resistant cultivars do not create a risk of secondary infection, the criterion given for resistance in EU Directive 69/464/EC. [source]

Evaluation of an action threshold-based IPM wheat model in Rheinland (Germany) in 1999/2001,

EPPO BULLETIN, Issue 3 2003
M. Heger
Under the specific agricultural and climatic conditions of Rheinland (DE), 48 field trials in three years demonstrated the practicability of the action threshold-based fungicide strategy of the IPM wheat model. The underlying data for action thresholds and dosage of fungicides applied are outlined. The cereal pathogens concerned, predominantly Mycosphaerella graminicola and Puccinia recondita, were controlled in the early stages of epidemic development using reduced rates of fungicides. The IPM wheat model gave a high efficacy of control, in terms of disease incidence and disease severity, under both low and high disease pressure conditions. The yield levels resulting from this effective reduction in diseases were nearly the same as those of the disease-free variant. Total yield increase varied between 15% and 30% with an overall average of around 20%, and resulted in monetary benefits of 50,100 EUR ha,1 in the years considered. [source]

Drinking pattern and risk of non-fatal myocardial infarction: a population-based case,control study

ADDICTION, Issue 3 2004
Maurizio Trevisan
ABSTRACT Aims Alcohol consumption has been associated with a reduced risk of heart disease incidence and mortality. However, most studies have focused on an average volume per specific time period and have paid little attention to the pattern of drinking. The aim of this study was to examine the association between various drinking patterns and myocardial infarction (MI). Design A population-based case,control study. Methods Participants were 427 white males with incident MI and 905 healthy white male controls (age 35,69 years) selected randomly from two Western New York counties. During computer-assisted interviews detailed information was collected regarding patterns of alcohol consumption during the 12,24 months prior to interview (controls) or MI (cases). Findings Compared to life-time abstainers, adjusted odds ratios (ORs) and 95% confidence interval (CI) for non-current and current drinkers were 0.66 (0.31,1.39) and 0.50 (0.24,1.02), respectively. Daily drinkers exhibited a significantly lower OR (0.41) compared to life-time abstainers. Participants who drank mainly without food had an OR of 1.49 (0.96,2.31) compared to those who drank mainly with food and 0.62 (0.28,1.37) compared to life-time abstainers. Men who reported drinking only at weekends had a significantly greater MI risk [1.91; (1.21,3.01)] compared to men who drank less than once/week, but not compared to life-time abstainers [0.91 (0.40,2.07)]. Conclusions Our results indicate that patterns of alcohol use have important cardiovascular health implications. [source]

Association of Sphaeropsis sapinea with insect-damaged red pine shoots and cones

FOREST PATHOLOGY, Issue 1 2003
E. Feci
Summary The association of the shoot blight and canker pathogen Sphaeropsis sapinea with red pine (Pinus resinosa) shoots and cones damaged by insects (especially Dioryctria sp.) was investigated. Samples from a single plantation approximately 35 years old, in Sauk Co., Wisconsin and also from three plantations, between approximately 40 and 50 years old, located in an area of pine shoot moth activity in the preceding year in Adams Co., Wisconsin were visually examined. Samples were arbitrarily collected from trees felled in the first plantation in May. Pycnidia of S. sapinea and insect damage were observed on 56 of 91 (62%) of closed cones and 17 of 165 (7%) of previous year's shoots. In the absence of insect damage, pycnidia of the pathogen were identified only on eight of 91 (9%) closed cones and never on previous year's shoots. In each of the other three plantations, 10 trees were located at intervals along transects in mid-June; one branch from the lower half of the crown per tree was pruned off, and both current and previous year's shoots were examined. Insect damage and S. sapinea pycnidia were too rare on current year's shoots to draw any conclusions. Insect damage occurred on 20,40% of over 2000 previous year's shoots that were examined, but pycnidia of the pathogen were identified on only about 5%. Although infrequent, S. sapinea was identified in association with insect-damaged previous year's shoots from these three plantations three times more frequently than those without insect damage. Random amplified polymorphic DNA (RAPD) markers from eight randomly selected isolates were consistent with the A group of S. sapinea, which can be aggressive on red pine. This ability to exploit insect-damaged shoots may facilitate long-term persistence of S. sapinea at low disease incidence and severity. The potential role of insect wounds as infection courts and insects as vectors of this important pathogen of pines deserves further study. Résumé L'étude a porté sur l'association entre le parasite de pousses et agent de chancre Sphaeropsis sapinea, et les pousses et cônes de Pinus resinosa endommagés par des insectes (surtout Dioryctria sp.). Des échantillons ont été examinés visuellement; ils provenaient d'une plantation d'environ 35 ans à Sauk Co., Wisconsin, et de trois plantations âgées d'environ 40 et 50 ans situées dans une zone où les insectes des pousses avaient été actifs l'année précédente à Adams Co., Wisconsin. Dans la première plantation, les échantillons ont été prélevés arbitrairement sur des arbres abattus en mai. Des pycnides de S. sapinea et des dégâts d'insectes ont été observés sur 56/91 (62%) des cônes fermés et sur 17/165 (7%) des pousses de l'année précédente. En l'absence de dégâts d'insectes, les pycnides n'ont été trouvées que sur 8/91 (9%) des cônes fermés, et jamais sur les pousses de l'année précédente. Dans chacune des trois autres plantations, 10 arbres ont été choisis à la mi-juin le long de transects ; sur chaque arbre une branche a été coupée dans la moitié inférieure de la couronne, et les pousses de l'année en cours et de l'année précédente ont été examinées. Sur les pousses de l'année, les dégâts d'insectes et les pycnides de S. sapineaétaient trop rares pour pouvoir en tirer des conclusions. Parmi plus de 2000 pousses de l'année précédente examinées, les dégâts d'insectes étaient présents sur 20,40% des pousses, mais les pycnides n'ont été trouvées que sur environ 5% d'entre elles. Bien que peu fréquent chez ces trois plantations, S. sapinea a été trouvé associé aux pousses de l'année précédente, 3 fois plus fréquemment chez celles endommagées par les insectes que chez les non endommagées. Pour huit isolats pris au hasard, les marqueurs RAPD ont indiqué leur appartenance au groupe A de S. sapinea qui peut être agressif sur P. resinosa. Cette aptitude de S. sapineaà utiliser les pousses endommagées par les insects peut faciliter sa persistance à long terme à des niveaux bas d'abondance et de dégâts. Le rôle potentiel des blessures d'insectes comme voies d'infection, et des insectes comme vecteurs du champignon parasite mérite d'être étudié. Zusammenfassung Es wurde die Assoziation zwischen Sphaeropsis sapinea (Erreger von Triebsterben und Rindennekrosen) und Schädigung an Trieben und Zapfen von Pinus resinosa untersucht, durch Insekten (vorwiegend Dioryctria sp.) untersucht. Proben von einer ca. 35 Jahre alten Plantage in Sauk Co., Wisconsin und von drei 40-50jährigen Plantagen mit Dioryctria -Befall im Vorjahr in Adams Co., Wisconsin wurden makroskopisch untersucht. Die Proben am ersten Standort wurden von Bäumen entnommen, die im Mai gefällt wurden (willkürliche Auswahl). Pyknidien und Schädigung durch Insekten wurden an 56/91 (62%) der geschlossenen Zapfen und an 17/165 (7%) der vorjährigen Triebe beobachtet. An Organen ohne Schädigung durch Insekten wurden die Pyknidien des Pathogens nur bei 8/91 (9%) der geschlossenen Zapfen und in keinem Fall an den vorjährigen Trieben nachgewiesen. In den anderen drei Plantagen wurden Mitte Juni je 10 Bäume entlang von Transekten untersucht; pro Baum wurde aus dem unteren Kronenbereich ein Ast abgeschnitten und sowohl die diesjährigen als auch die vorjährigen Triebe wurden untersucht. An den diesjährigen Triebabschnitten waren sowohl Schädigungen durch Insekten als auch Pyknidien von S. sapinea zu selten, um daraus Schlüsse zu ziehen. An den vorjährigen Triebabschnitten kamen Insektenschäden an 20,40% von über 2,000 untersuchten Objekten vor, aber Pyknidien des Pathogens wurden nur in 5% der Fälle nachgewiesen. Trotz des geringen Vorkommens wurde S. sapinea auf den vorjährigen und von Insekten beschädigten Trieben dreimal häufiger nachgewiesen als an Trieben ohne Beschädigung. Acht zufällig ausgewählte Isolate wurden anhand von RAPD Markern der Gruppe A von S. sapinea zugeordnet, die auf P. resinosa agressiv sein kann. Die Fähigkeit von S. sapinea, durch Insekten beschädigte Triebe zu nutzen, kann das Überdauern des Pilzes auf einem niedrigen Befallsniveau erleichtern. Die Bedeutung von Wunden, die durch Insekten verursacht werden, als Infektionspforten und die mögliche Rolle von Insekten als Vektoren dieses wichigen Pathogens sollte in weiteren Untersuchungen geklärt werden. [source]

Effects of heat treatment on the quality of fresh-cut Chinese water chestnut

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2004
Litao Peng
Summary A heat treatment to inhibit browning and maintain the quality of fresh-cut Chinese water chestnut was developed. Slices of Chinese water chestnut, cv. Guilin, were immersed in boiling water for 30 s, placed into film-wrapped trays and then stored at 4 °C for up to 12 days. Changes in browning, eating quality and disease incidence were measured. The effect of heat treatment on the content of total phenolics and activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was also evaluated. The heat treatment effectively prevented browning associated with PAL, PPO and POD activities and total phenolic content and delayed the decrease in eating quality, which is associated with reduced total soluble solids, titratable acidity and ascorbic acid, compared with fresh-cut Chinese water chestnut. Inhibition of browning by heat treatment without microbial growth was achieved for 12 days of storage at 4 °C. These results showed that heat treatment effectively maintained the quality of fresh-cut Chinese water chestnut. [source]

Role of lipopeptides produced by Bacillus subtilis GA1 in the reduction of grey mould disease caused by Botrytis cinerea on apple

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2004
Y. Touré
Abstract Aim:, Test of Bacillus subtilis strain GA1 for its potential to control grey mould disease of apple caused by Botrytis cinerea. Methods and Results:, GA1 was first tested for its ability to antagonize in vitro the growth of a wide variety of plant pathogenic fungi responsible for diseases of economical importance. The potential of strain GA1 to reduce post-harvest infection caused by B. cinerea was tested on apples by treating artificially wounded fruits with endospore suspensions. Strain GA1 was very effective at reducing disease incidence during the first 5 days following pathogen inoculation and a 80% protection level was maintained over the next 10 days. Treatment of fruits with an extract of GA1 culture supernatant also exerted a strong preventive effect on the development of grey mould. Further analysis of this extract revealed that strain GA1 produces a wide variety of antifungal lipopeptide isomers from the iturin, fengycin and surfactin families. A strong evidence for the involvement of such compounds in disease reduction arose from the recovery of fengycins from protected fruit sites colonized by bacterial cells. Conclusions:, The results presented here demonstrate that, despite unfavourable pH, B. subtilis endospores inoculated on apple pulp can readily germinate allowing significant cell populations to establish and efficient in vivo synthesis of lipopeptides which could be related to grey mould reduction. Significance and Impact of the Study:, This work enables for the first time to correlate the strong protective effect of a particular B. subtilis strain against grey mould with in situ production of fengycins in infected sites of apple fruits. [source]

A nurse-led cardiac rehabilitation programme improves health behaviours and cardiac physiological risk parameters: evidence from Chengdu, China

JOURNAL OF CLINICAL NURSING, Issue 10 2007
Xiaolian Jiang MSc
Aim., The aim of this study was to examine the effect of a cardiac rehabilitation programme on health behaviours and physiological risk parameters in patients with coronary heart disease in Chengdu, China. Background., Epidemiological studies indicate a dose-, level- and duration-dependent relationship exists between cardiac behavioural and physiological risks and coronary heart disease incidence as well as subsequent cardiac morbidity and mortality. Cardiac risk factor modification has become the very primary goal of modern cardiac rehabilitation programmes. Design methods., A randomized controlled trial was conducted. Coronary heart disease patients (n = 167) who met the sampling criteria in two tertiary medical centres in Chengdu, south-west China, were randomly assigned to either an intervention group (the cardiac rehabilitation programme) or control group (the routine care). The change of health behaviours (walking performance, step II diet adherence, medication adherence, smoking cessation) and physiological risk parameters (serum lipids, blood pressure, body weight) were assessed to evaluate the programme effect. Results., Patients in the intervention group demonstrated a significantly better performance in walking, step II diet adherence, medication adherence; a significantly greater reduction in serum lipids including triglyceride, total cholesterol, low-density lipoprotein; and significantly better control of systolic and diastolic blood pressure at three months. The majority of these positive impacts were maintained at six months. The effect of the programme on smoking cessation, body weight, serum high-density lipoprotein, was not confirmed. Conclusions., A cardiac rehabilitation programme led by a nurse can significantly improve the health behaviours and cardiac physiological risk parameters in coronary heart disease patients. Nurses can fill significant treatment gaps in the risk factor management of patients with coronary heart disease. Relevance to clinical practice., This study raises attention regarding the important roles nurses can play in cardiac rehabilitation and the unique way for nurses to meet the rehabilitative care needs of coronary heart disease patients. Furthermore, the hospital,home bridging nature of the programme also created a model for interfacing the acute care and community rehabilitative care. [source]

Short-term epidemic dynamics in the Cakile maritima,Alternaria brassicicola host,pathogen association

JOURNAL OF ECOLOGY, Issue 5 2001
Peter H. Thrall
Summary 1Studies combining within- and among-population processes are crucial for understanding ecological and co-evolutionary dynamics in host,pathogen interactions. We report on work over an 18-month period involving multiple beach populations of the plant Cakile maritima and its fungal pathogen Alternaria brassicicola along the south-east coast of Australia. 2Results from permanent transects replicated on several beaches show that disease incidence and prevalence vary significantly with plant age, class and distance from the sea, as well as time during the season. Plant density is also positively related to disease levels. 3Results from three subregions indicate that disease persistence depends on survival of infected plants behind the foredunes of protected beaches. Population extinction was more likely on beaches with greater wind exposure and sea access, with the latter also related to colonization consistent with the dispersal of Cakile seeds via ocean currents. 4Although disease dynamics during the epidemic were similar across subregions, the severity of the epidemic varied significantly among these areas, suggesting that large-scale environmental factors may influence the timing and development of the epidemic. 5Estimates of synchrony in disease dynamics indicated that populations within a subregion were significantly correlated with respect to epidemic development. There was, however, no evidence for spatial synchrony in disease dynamics based on among-population covariances in disease prevalence and interbeach distances. Populations within a subregion were thus often at quite different phases of the epidemic at any given time. [source]

Male and female Silene latifolia plants differ in per-contact risk of infection by a sexually transmitted disease

JOURNAL OF ECOLOGY, Issue 1 2001
Oliver Kaltz
Summary 1,Behavioural, physiological or immunological constraints often render one sex more susceptible to parasites, thereby potentially generating sex-specific trade-offs between traits associated with infection risk and other life-history characters. 2,The fungal pathogen Microbotryum violaceum systemically infects the dioecious plant Silene latifolia when pollinators deposit fungal spores on the flowers of healthy plants. Male plants produce many short-lived flowers, whereas females produce few flowers that remain connected with the plant after fertilization. We investigated how variation in flower production and flower longevity affects the infection risk for males and females. 3,In glasshouse experiments, we varied the number of flowers inoculated (4 vs. 16 per plant) with spores and the time until these flowers were removed (1 or 2 days for both sexes, 14 days for females only). We also measured the longevity of male flowers receiving simulated visits, with or without spores, to test for an abscission response to visitation and/or contamination. In a field survey, we measured male and female disease prevalence in 17 natural populations. 4,Varying the number of inoculated flowers did not affect infection probability, but females retaining inoculated flowers for 14 days became diseased more often (20.0%) than did plants with flowers removed within 2 days (7.3%). 5,Males that had dropped more inoculated flowers prematurely were more likely to remain uninfected. Spore-bearing visits shortened male flower longevity (38.4 ± 2.8 h) relative to non-spore visits (47.9 ± 5.2 h). 6,Female field disease prevalence (19.7 ± 3.5%) was higher than that of males (14.3 ± 2.6%), especially in populations with a high disease incidence. 7,Continuing physical connection during fruit ripening appears to increase invasion time and thus the per-contact infection risk in females. This is consistent with higher female field prevalences, although other explanations, unrelated to disease transmission, are possible. These results illustrate how interactions between plant reproductive behaviour and pollinator activity may affect disease spread. Female mating behaviour may evolve towards lower attractiveness to pollinators to minimize infectious contacts, while males can afford to be more promiscuous with an attractive, but disposable, floral display. [source]

A 5-year follow-up study of disease incidence in men with an abnormal hormone pattern

JOURNAL OF INTERNAL MEDICINE, Issue 4 2003
R. Rosmond
Abstract Rosmond R, Wallerius S, Wanger P, Martin L, Holm G, Björntorp P (The Cardiovascular Institute, Sahlgrenska University Hospital, Göteborg; and Huddinge University Hospital, Huddinge; Sweden). A 5-year follow-up study of disease incidence in men with an abnormal hormone pattern. J Intern Med 2003; 254: 386,390. Objectives. Previous studies have suggested that abnormal levels of cortisol and testosterone might increase the risk of serious somatic diseases. To test this hypothesis, we conducted a 5-year follow-up study in middle-aged men. Methods. A population-based cohort study conducted in 1995 amongst 141 Swedish men born in 1944, in whom a clinical examination supplemented by medical history aimed to disclose the presence of cardiovascular disease (CVD) (myocardial infarction, angina pectoris, stroke), type 2 diabetes and hypertension were performed at baseline and at follow-up in the year 2000. In addition, salivary cortisol levels were measured repeatedly over the day. Serum testosterone concentrations were also determined. Using the baseline data, an algorithm was constructed, which classified the secretion pattern of cortisol and testosterone from each individual as being normal or abnormal. Results. By the end of follow-up, men with an abnormal hormone secretion pattern (n = 73) had elevated mean arterial pressure (P = 0.003), fasting insulin (P = 0.009) and insulin : glucose ratio (P = 0.005) compared with men with a normal secretion pattern (n = 68). Body mass index, waist circumference, and waist : hip ratio were significantly elevated in both groups. However, the 5-year incidence of CVD, type 2 diabetes, and hypertension were significantly higher (P < 0.001) in men with an abnormal neuroendocrine secretory pattern compared to men with a normal pattern. Conclusions. These data suggest that an abnormal neuroendocrine secretory pattern is prospectively associated with an increased incidence of cardiovascular-related events and type 2 diabetes. [source]

Association of boiled and filtered coffee with incidence of first nonfatal myocardial infarction: the SHEEP and the VHEEP study

JOURNAL OF INTERNAL MEDICINE, Issue 6 2003
N. Hammar
Abstract., Hammar N, Andersson T, Alfredsson L, Reuterwall C, Nilsson T, Hallqvist J, Knutsson A, Ahlbom A (Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Stockholm Center of Public Health, Stockholm, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Västernorrland County Council, Sundsvall, Division of Social Medicine, Karolinska Institutet, Stockholm, Norrland University Hospital, Umeå, Sweden) Association of boiled and filtered coffee with incidence of first nonfatal myocardial infarction: the SHEEP and the VHEEP study. J Intern Med 2003; 253: 653,659. Objectives., To evaluate the influence of consumption of filtered and boiled coffee, on the incidence of first nonfatal myocardial infarction. Design., Population-based case,control study. Setting and subjects., The study base consisted of the population 45,65/70 years-old in two Swedish counties, Stockholm and Västernorrland, 1992/93,94. In all, 1943 cases of first nonfatal myocardial infarction were identified. For each case one control was selected from the study base concurrently with disease incidence by matching the sex, age and place of residence of the case. Information about coffee consumption and other factors was obtained by mailed questionnaire and a medical examination. The participation rate was 85% amongst cases and 74% amongst controls. Results., Men with a reported consumption of 7,9 dL filtered coffee per day showed an increased incidence of first myocardial infarction compared with consumers of 3 dL day,1 or less (RR: 1.32; 95% CI: 1.03,1.70). A consumption of at least 10 dL day,1 was associated with an RR of 1.93 (95% CI: 1.42,2.63) for filtered and 2.20 (95% CI: 1.17,4.15) for boiled coffee. Amongst women, no clear association was seen between consumption of filtered coffee and myocardial infarction but consumption of boiled coffee tended to be related to an increased incidence. Comparing subjects drinking boiled coffee with those drinking filtered coffee and adjusting for the amount consumed gave an increased incidence for boiled coffee amongst both men (RR: 1.41; 95% CI: 1.07,1.80) and women (RR: 1.63; 95% CI: 1.04,2.56). Conclusions., Consumption of boiled coffee appears to increase the incidence of first nonfatal myocardial infarction. This increased incidence is consistent with randomized trials showing an adverse impact of boiled coffee on blood lipids. [source]

Variety-specific Epidemiology of Cercospora beticola Sacc. and Consequences for Threshold-based Timing of Fungicide Application in Sugar Beet

JOURNAL OF PHYTOPATHOLOGY, Issue 4 2010
Ulrike Kaiser
Abstract In Central Europe, fungicides to control leaf spot disease in sugar beet caused by Cercospora beticola are applied based on thresholds of disease incidence (DI, per cent of infected plants). As variety-specific fungicide application was not analyzed to date, the epidemiology of C. beticola and its effect on white sugar yield (WSY) in varieties with different susceptibility were investigated at seven sites in Germany and Austria in 2004 and 2005. All varieties reached the summary thresholds 5 / 15 / 45% DI in all environments. Fitting a logistic growth curve to DI revealed significant differences among varieties. At high disease pressure, susceptible varieties reached a considerably higher disease severity (DS, per cent of infected leaf area) at harvest and a larger area under disease progress curve (AUDPC) than resistant varieties. Fitting a logistic growth curve to DS showed an increasing differentiation among varieties with time. The growth rate estimated based on the logistic growth curve was the only variable that performed equally well in differentiating varieties under low and high disease pressure. With increasing disease pressure, varieties differed considerably in WSY, but differences between susceptible and resistant varieties were significant only in some environments. The disease-loss relation between AUDPC and relative WSY was variety-specific. Resistant varieties had an approximately identical WSY with and without infection and compensated for negative infection effects even at higher AUDPC. Therefore, at high disease pressure, resistant varieties had a higher relative yield compared to susceptible ones. However, our results indicate that there is no need to develop variety-specific thresholds, but resistant varieties reach the established thresholds later than susceptible ones. Consequently, the time of fungicide application can be delayed in resistant varieties. This will help to reduce the use of fungicides to the bare essentials as requested for the integrated crop protection management. [source]

Variation in Resistance of Camelina (Camelina sativa [L.] Crtz.) to Downy Mildew (Peronospora camelinae Gäum.)

JOURNAL OF PHYTOPATHOLOGY, Issue 3-4 2001
Vollmann
Camelina (Camelina sativa) is a potential oilseed crop for both food and non-food utilization cultivated on a limited acreage in Europe and North America. An important low-input feature of camelina is its high level of resistance against plant diseases, which may partly be due to the production of antimicrobially efficient phytoalexins. In Central European countries such as Austria, downy mildew (Peronospora camelinae) is the only disease of camelina which has been found repeatedly, whereas other diseases and pests have been observed only occasionally. Therefore, the genotypic variation of downy mildew incidence was evaluated in two camelina field experiments carried out within a breeding programme. In both experiments, totally resistant breeding lines were identified and a continuous pattern of variation in disease incidence was observed, suggesting a horizontal type of resistance. In bi-parental populations, disease incidence of progeny appeared to be associated with disease scores of the parent genotypes, and transgressive segregation in disease incidence was also found. In 1998, the rate of downy mildew in camelina was lower than in 1999; in the latter growing season, grain yield was significantly affected by the disease, whereas other agronomic characters remained unaffected. Variation der Resistenz von Leindotter (Camelina sativa[L.] Crtz.) gegen Falschen Mehltau (Peronospora camelinae Gäum.) Leindotter (Camelina sativa) ist eine Ölpflanze, die zur Nahrungsmittelherstellung und für andere Zwecke genutzt werden kann und in Europa und Nordamerika auf relativ kleiner Fläche angebaut wird. Ein wichtiges Low-Input-Merkmal des Leindotters ist seine hohe Krankheitsresistenz, die vermutlich teilweise auf die Bildung antimikrobiell wirksamer Phytoalexine zurückgeht. In Österreich und anderen Ländern Mitteleuropas ist Falscher Mehltau (Peronospora camelinae) die einzige regelmäßig anzutreffende Krankheit des Leindotters, andere Krankheiten und Schädlinge werden nur gelegentlich beobachtet. Daher wurde die genotypische Variation der Inzidenz des Falschen Mehltaus im Rahmen eines Leindotter-Züchtungsprogramms in zwei Feldversuchen geprüft. In beiden Versuchen wurden vollständig resistente Zuchtlinien identifiziert, und ein kontinuierliches Variationsmuster der Krankheitsresistenz wurde beobachtet, was auf horizontale Resistenz schließen läßt. In biparentalen Populationen war die Befallshänfigkeit bei den Nachkommen offenbar mit den Boniturwerten der elterlichen Genotypen assoziiert, und bei der Befallshänfigkeit wurde auch eine transgressive Aufspaltung beobachtet. 1998 war der Befall des Leindotters mit Falschem Mehltau geringer als 1999; im letztgenannten Jahr war der Kornertrag infolge der Krankheit deutlich verringert, während andere agronomische Merkmale unbeeinflußt blieben. [source]

Present and past old-growth forests of the Lake Tahoe Basin, Sierra Nevada, US

The incidence of Crohn's disease in Cardiff over the last 75 years: an update for 1996,2005

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2008
S. GUNESH
Summary Background The incidence of Crohn's disease rose rapidly in industralized countries over the past 50 years, but it is unclear whether the incidence is still rising or has reached a plateau. Aims, To update the long-term incidence study of Crohn's disease in Cardiff for 1996,2005, to investigate whether incidence is still rising and to study changes in disease characteristics over time. Method, Crohn's cases identified by retrospective analysis of hospital records as in previous studies in Cardiff. Results, Two hundred and twelve cases were identified. Corrected incidence for this decade was 66 × 106 per year (95% confidence interval: 58,76), showing a continuing rise compared to previous decades. The proportion with colonic disease at presentation continues to rise (43%) with a corresponding fall in those with terminal ileal disease. There remains a strong female preponderance (F:M 1.6:1) as in previous studies. The incidence in children under age 16 continues to rise, and the median age at diagnosis has fallen slightly. Conclusion, Crohn's disease incidence continues to rise slowly in Cardiff with a continuing increase in those presenting with colonic disease, which is now the commonest disease pattern. [source]

Allelochemical tricin in rice hull and its aurone isomer against rice seedling rot disease

A method for selecting and monitoring medication sales for surveillance of gastroenteritis,

PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 10 2010
Camille Pelat
Abstract Purpose Monitoring appropriate categories of medication sales can provide early warning of certain disease outbreaks. This paper presents a methodology for choosing and monitoring medication sales relevant for the surveillance of gastroenteritis and assesses the operational characteristics of the selected medications for early warning. Methods Acute diarrhoea incidences in mainland France were obtained from the Sentinelles network surveillance system for the period 2000,2009. Medication sales grouped by therapeutic classes were obtained on the same period. Hierarchical clustering was used to select therapeutic classes correlating with disease incidence over the period. Alert thresholds were defined for the selected therapeutic classes. Single and multiple voter algorithms were investigated for outbreak detection based on sales crossing the thresholds. Sensitivity and specificity were calculated respective to known outbreaks periods. Results Four therapeutic classes were found to cluster with acute diarrhoea incidence. The therapeutic class other antiemetic and antinauseants had the best sensitivity (100%) and timeliness (1.625 weeks before official alerts), for a false alarm rate of 5%. Multiple voter algorithm was the most efficient with the rule: ,Emit an outbreak alert when at least three therapeutic classes are over their threshold' (sensitivity 100%, specificity 95%, timeliness 1.750 weeks before official alerts). Conclusions The presented method allowed selection of relevant therapeutic classes for surveillance of a specific condition. Multiple voter algorithm based on several therapeutic classes performed slightly better than the best therapeutic class alone, while improving robustness against abrupt changes occurring in a single therapeutic class. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Studies on the epidemiology and yield losses from rice black-streaked dwarf disease in a recent epidemic in Zhejiang province, China

PLANT PATHOLOGY, Issue 5 2009
H.-D. Wang
The spread of rice black-streaked dwarf disease, which has emerged as a major problem on winter wheat and the two summer rice crops (early indica and late japonica) grown in central and southern Zhejiang province, China, is documented from 1995 to 2007. The late japonica crop suffered the most: up to 64 640 ha were affected with estimated losses of c. 120 000 t grain per year. Peak adult numbers of the small brown planthopper vector, Laodelphax striatellus, coincided with the seedling stages of both rice crops and the proportion of the insect population carrying virus increased during 1998,2005. Seedlings with three to four leaves were the most susceptible, whereas plants inoculated after the end of tillering developed few or no symptoms. Disease levels were strongly correlated with numbers of viruliferous vectors. In sowing-date experiments with both rice crops, the earliest sowings had the most disease and suffered the greatest yield losses. With the last sowing date (25 days after the first), there were almost no losses. There were yield losses of 0·80% for every 1% increase in disease incidence in early indica rice and rather more (0·92%) in the late japonica crop. There were large differences in susceptibility between cultivars, indicating the possibility, within currently available germplasm, of using more resistant cultivars to help contain the disease. Changes in cropping practice and in recent winter weather conditions have probably contributed to the emergence of the virus as a major pathogen in eastern China. [source]

Size, shape and intensity of aggregation of take-all disease during natural epidemics in second wheat crops

PLANT PATHOLOGY, Issue 1 2007
M. Gosme
Point pattern analysis (fitting of the beta-binomial distribution and binary form of power law) was used to describe the spatial pattern of natural take-all epidemics (caused by Gaeumannomyces graminis var. tritici) on a second consecutive crop of winter wheat in plots under different cropping practices that could have an impact on the quantity and spatial distribution of primary inoculum, and on the spread of the disease. The spatial pattern of take-all was aggregated in 48% of the datasets when disease incidence was assessed at the plant level and in 83% when it was assessed at the root level. Clusters of diseased roots were in general less than 1 m in diameter for crown roots and 1,1·5 m for seminal roots; when present, clusters of diseased plants were 2,2·5 m in diameter. Anisotropy of the spatial pattern was detected and could be linked to soil cultivation. Clusters did not increase in size over the cropping season, but increased spatial heterogeneity of the disease level was observed, corresponding to local disease amplification within clusters. The relative influences of autonomous spread and inoculum dispersal on the size and shape of clusters are discussed. [source]