Spatial Analysis: Techniques which study entities using their topological, geometric, or geographic properties.Geographic Information Systems: Computer systems capable of assembling, storing, manipulating, and displaying geographically referenced information, i.e. data identified according to their locations.Space-Time Clustering: A statistically significant excess of cases of a disease, occurring within a limited space-time continuum.Geographic Mapping: Creating a representation of areas of the earth or other celestial bodies, for the purpose of visualizing spatial distributions of various information.Topography, Medical: The systematic surveying, mapping, charting, and description of specific geographical sites, with reference to the physical features that were presumed to influence health and disease. Medical topography should be differentiated from EPIDEMIOLOGY in that the former emphasizes geography whereas the latter emphasizes disease outbreaks.Geography: The science dealing with the earth and its life, especially the description of land, sea, and air and the distribution of plant and animal life, including humanity and human industries with reference to the mutual relations of these elements. (From Webster, 3d ed)Demography: Statistical interpretation and description of a population with reference to distribution, composition, or structure.Cluster Analysis: A set of statistical methods used to group variables or observations into strongly inter-related subgroups. In epidemiology, it may be used to analyze a closely grouped series of events or cases of disease or other health-related phenomenon with well-defined distribution patterns in relation to time or place or both.Maps as Topic: Representations, normally to scale and on a flat medium, of a selection of material or abstract features on the surface of the earth, the heavens, or celestial bodies.Satellite Communications: Communications using an active or passive satellite to extend the range of radio, television, or other electronic transmission by returning signals to earth from an orbiting satellite.Pygeum: A plant genus of the family ROSACEAE. Bark extract of P. africanum is an ingredient of folk remedies to treat PROSTATIC HYPERPLASIA.Spatio-Temporal Analysis: Techniques which study entities using their topological, geometric, or geographic properties and include the dimension of time in the analysis.BrazilGeography, Medical: The area of medicine concerned with the effects on health and disease due to geographic factors such as CLIMATE, environmental conditions, and geographic location.Population Density: Number of individuals in a population relative to space.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Urban Population: The inhabitants of a city or town, including metropolitan areas and suburban areas.Bayes Theorem: A theorem in probability theory named for Thomas Bayes (1702-1761). In epidemiology, it is used to obtain the probability of disease in a group of people with some characteristic on the basis of the overall rate of that disease and of the likelihood of that characteristic in healthy and diseased individuals. The most familiar application is in clinical decision analysis where it is used for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result.Remote Sensing Technology: Observation and acquisition of physical data from a distance by viewing and making measurements from a distance or receiving transmitted data from observations made at distant location.Small-Area Analysis: A method of analyzing the variation in utilization of health care in small geographic or demographic areas. It often studies, for example, the usage rates for a given service or procedure in several small areas, documenting the variation among the areas. By comparing high- and low-use areas, the analysis attempts to determine whether there is a pattern to such use and to identify variables that are associated with and contribute to the variation.Residence Characteristics: Elements of residence that characterize a population. They are applicable in determining need for and utilization of health services.Population Surveillance: Ongoing scrutiny of a population (general population, study population, target population, etc.), generally using methods distinguished by their practicability, uniformity, and frequently their rapidity, rather than by complete accuracy.Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Models, Statistical: Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.Endemic Diseases: The constant presence of diseases or infectious agents within a given geographic area or population group. It may also refer to the usual prevalence of a given disease with such area or group. It includes holoendemic and hyperendemic diseases. A holoendemic disease is one for which a high prevalent level of infection begins early in life and affects most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than do children (malaria in many communities is a holoendemic disease). A hyperendemic disease is one that is constantly present at a high incidence and/or prevalence rate and affects all groups equally. (Last, A Dictionary of Epidemiology, 3d ed, p53, 78, 80)Leprosy: A chronic granulomatous infection caused by MYCOBACTERIUM LEPRAE. The granulomatous lesions are manifested in the skin, the mucous membranes, and the peripheral nerves. Two polar or principal types are lepromatous and tuberculoid.Censuses: Enumerations of populations usually recording identities of all persons in every place of residence with age or date of birth, sex, occupation, national origin, language, marital status, income, relation to head of household, information on the dwelling place, education, literacy, health-related data (e.g., permanent disability), etc. The census or "numbering of the people" is mentioned several times in the Old Testament. Among the Romans, censuses were intimately connected with the enumeration of troops before and after battle and probably a military necessity. (From Last, A Dictionary of Epidemiology, 3d ed; Garrison, An Introduction to the History of Medicine, 4th ed, p66, p119)Cities: A large or important municipality of a country, usually a major metropolitan center.Water Supply: Means or process of supplying water (as for a community) usually including reservoirs, tunnels, and pipelines and often the watershed from which the water is ultimately drawn. (Webster, 3d ed)Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Poverty Areas: City, urban, rural, or suburban areas which are characterized by severe economic deprivation and by accompanying physical and social decay.Environment: The external elements and conditions which surround, influence, and affect the life and development of an organism or population.Conservation of Natural Resources: The protection, preservation, restoration, and rational use of all resources in the total environment.China: A country spanning from central Asia to the Pacific Ocean.Epidemiological Monitoring: Collection, analysis, and interpretation of data about the frequency, distribution, and consequences of disease or health conditions, for use in the planning, implementing, and evaluating public health programs.Disease Outbreaks: Sudden increase in the incidence of a disease. The concept includes EPIDEMICS and PANDEMICS.Urban Health: The status of health in urban populations.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Socioeconomic Factors: Social and economic factors that characterize the individual or group within the social structure.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Rural Population: The inhabitants of rural areas or of small towns classified as rural.Disease Reservoirs: Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (DISEASE VECTORS) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks.Malaria: A protozoan disease caused in humans by four species of the PLASMODIUM genus: PLASMODIUM FALCIPARUM; PLASMODIUM VIVAX; PLASMODIUM OVALE; and PLASMODIUM MALARIAE; and transmitted by the bite of an infected female mosquito of the genus ANOPHELES. Malaria is endemic in parts of Asia, Africa, Central and South America, Oceania, and certain Caribbean islands. It is characterized by extreme exhaustion associated with paroxysms of high FEVER; SWEATING; shaking CHILLS; and ANEMIA. Malaria in ANIMALS is caused by other species of plasmodia.Climate: The longterm manifestations of WEATHER. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Poisson Distribution: A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Agriculture: The science, art or practice of cultivating soil, producing crops, and raising livestock.Population Dynamics: The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.North CarolinaEnvironmental Exposure: The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Data Interpretation, Statistical: Application of statistical procedures to analyze specific observed or assumed facts from a particular study.Insect Vectors: Insects that transmit infective organisms from one host to another or from an inanimate reservoir to an animate host.Epidemiologic Methods: Research techniques that focus on study designs and data gathering methods in human and animal populations.Age Distribution: The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Ontario: A province of Canada lying between the provinces of Manitoba and Quebec. Its capital is Toronto. It takes its name from Lake Ontario which is said to represent the Iroquois oniatariio, beautiful lake. (From Webster's New Geographical Dictionary, 1988, p892 & Room, Brewer's Dictionary of Names, 1992, p391)Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Social Class: A stratum of people with similar position and prestige; includes social stratification. Social class is measured by criteria such as education, occupation, and income.Sex Distribution: The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Infant, Newborn: An infant during the first month after birth.Health Services Accessibility: The degree to which individuals are inhibited or facilitated in their ability to gain entry to and to receive care and services from the health care system. Factors influencing this ability include geographic, architectural, transportational, and financial considerations, among others.Models, Theoretical: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Risk: The probability that an event will occur. It encompasses a variety of measures of the probability of a generally unfavorable outcome.Genetic Variation: Genotypic differences observed among individuals in a population.Logistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.