Epidemiology

A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 16,000 of the millions of virus species have been described in detail. The study of viruses is

An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection.

Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population, and application of this knowledge to prevent diseases.

reduction of human social interaction in an effort to prevent the spread of infectious disease

measure of the number of deaths in a population from a given cause, scaled by population, in a set period of time

protection from infectious disease that occurs when a sufficient fraction of a population has become immune (through vaccination or previous infections)

time between an infection and the onset of disease symptoms

epidemiological term describing a disease which is constantly present in a specific area

thumb|upright=1.8|A depiction of prevalence In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number of people found to have the condition with the total number of people studied and is usually expressed as a fraction, a percentage, or the number of cases per 10,000 or 100,000 people. Prevalence is most often used in questionnaire studies.

four criteria showing a causal relationship between a causative microbe and a disease

agent that carries and transmits an infectious pathogen into another living organism

metric in epidemiology showing average measure of a pathogen’s infectiousness

Serology is the scientific study of antibodies in the serum and other body fluids. Such antibodies are typically formed in response to an infection (against a given microorganism), against other foreign proteins (in response, for example, to a mismatched blood transfusion), or to one's own proteins (in instances of autoimmune disease).

measure of the probability of occurrence of a given medical condition in a population within a specified period of time

In medicine, comorbidity refers to the simultaneous presence of two or more medical conditions in a person; often co-occurring (that is, concomitant or concurrent) with a primary condition. It originates from the Latin term (meaning "sickness") prefixed with ("together") and suffixed with -ity (to indicate a state or condition). Comorbidity includes all additional ailments a person may experience alongside a primary diagnosis, which can be either physiological or psychological in nature. In the context of mental health, comorbidity may refer to the concurrent existence of mental disorders, for

process of finding and identifying people in close contact with someone who is infected with a transmissible pathogen

the proportion of deaths from an infectious disease compared to the number of diagnosed cases

initial patient in the population of an epidemiological investigation

in statistics and epidemiology

form of longitudinal study

living host, such as an animal or a plant, inside of which an infectious pathogen naturally lives and reproduces

sudden increase in occurrences of a disease in a particular time and place

catchphrase for the apparent paradox that French people have a low incidence of heart disease while consuming many saturated fats

statistic quantifying the association between two events

specific disease or injury resulting in a human's death, which may be recorded on a death certificate

Lethality (also called deadliness or perniciousness) is how capable something is of causing death. Most often it is used when referring to diseases, chemical weapons, biological weapons, or their toxic chemical components. The use of this term denotes the ability of these weapons to kill, but also the possibility that they may not kill. Reasons for the lethality of a weapon to be inconsistent, or expressed by percentage, can be as varied as minimized exposure to the weapon, previous exposure to the weapon minimizing susceptibility, degradation of the weapon over time and/or distance, and incor

type of study based on universal sampling

health conditions thought to be a result of increasing wealth in society

reason or origination of some disease

amount of virus found in host tissue or a given volume of fluid

type of observational study comparing two existing groups differing in outcome

empirical study in which individuals/clusters exposed to the experimental and control conditions are determined by factors outside the control of the investigators (nature), but the process governing the exposures arguably resembles random assignment

subset category of transmissible diseases, which are transmitted to other persons

complete extermination of a disease-causing agent to reduce its incidence to zero

biological observation of cancer rate not correlating with number of cells in an organism

In epidemiology, infectivity is the ability of a pathogen to establish an infection. More specifically, infectivity is the extent to which the pathogen can enter, survive, and multiply in a host. It is measured by the ratio of the number of people who become infected to the total number exposed to the pathogen.

Database at Stanford University that tracks 93 common mutations of HIV

thumb|right|Detecting whether medics have inadvertently transferred fluids to their clothing during a training sequence using simulated bodily fluids carrying an ultraviolet dye A fomite () or fomes () is any inanimate object that, when contaminated with or exposed to infectious agents (such as pathogenic bacteria, viruses or fungi), can transfer disease to a new host.

Veterinary epidemiology (also known as epizootiology or epizoology) is the branch of epidemiology that studies the frequency, distribution, and determinants of health and disease in animal populations. While human epidemiology focuses on disease in human populations, veterinary epidemiology applies the same principles and methods to domestic animals, livestock, and wildlife, with the goal of preventing, mitigating, or eliminating the impact of disease in susceptible populations. In veterinary practice, epidemiological methods are used not only to enhance animal health but also to improve produ

hypothesis in medicine that early childhood exposure to certain microorganisms (e.g. gut flora, helminths) protects against allergies

percentage of people in a study or treatment group still alive for a given period of time after diagnosis

public health measurements

diagnostic test or benchmark that is the best available under reasonable conditions

virtual pandemic in World of Warcraft, which began on 13 Sept. 2005 and lasted for a month

medical field concerned with preventing healthcare-associated infection, a practical sub-discipline of epidemiology

public health strategy

Principles for establishing a causal relationship

ecological sampling method

average number of patients who need to be treated to prevent one additional bad outcome

low life expectancy and poor health of residents of Scotland, and Glasgow in particular, compared to the rest of Europe

Coinfection is the simultaneous infection of a host by multiple pathogen species. In virology, coinfection includes simultaneous infection of a single cell by two or more virus particles. An example is the coinfection of liver cells with hepatitis B virus and hepatitis D virus, which can arise incrementally by initial infection followed by superinfection.

Pharmacoepidemiology is the study of the uses and effects of drugs in well-defined populations.

type of survival rate

pandemic of Human Immunodeficiency Virus

percentage of the population that contracts the disease in an at risk population during a specified time interval

Enzootic describes the situation where a disease or pathogen is continuously present in at least one species of non-human animal in a particular region. It is the non-human equivalent of endemic.

medical facility

sexual behavior risking contracting sexually transmitted disease or pregnancy

diseases more prevalent in low-income populations

using a mathematical model to understand infectious disease transmission and predict the likely outcome of an epidemic