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In epidemiology
Epidemiology

Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine....
, an infection that is epidemic (from Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 epi- upon + demos people) appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected," based on recent experience (the number of new cases in the population during a specified period of time is called the "incidence rate"). (An epizootic
Epizootic

In epizoology, an epizootic is a disease that appears as new cases in a given animal population, during a given period, at a rate that substantially exceeds what is "expected" based on recent experience ....
 is the analogous circumstance within an animal population.) In recent usages, the disease is not required to be communicable.

Classification
Defining an epidemic can be subjective, depending in part on what is "expected".






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In epidemiology
Epidemiology

Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine....
, an infection that is epidemic (from Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 epi- upon + demos people) appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected," based on recent experience (the number of new cases in the population during a specified period of time is called the "incidence rate"). (An epizootic
Epizootic

In epizoology, an epizootic is a disease that appears as new cases in a given animal population, during a given period, at a rate that substantially exceeds what is "expected" based on recent experience ....
 is the analogous circumstance within an animal population.) In recent usages, the disease is not required to be communicable.

Classification


Defining an epidemic can be subjective, depending in part on what is "expected". An epidemic may be restricted to one local (an outbreak), more general (an "epidemic") or even global (pandemic
Pandemic

A pandemic is an epidemic of infectious disease that spreads through populations across a large region; for instance a continent, or even worldwide....
). Because it is based on what is "expected" or thought normal, a few cases of a very rare disease like rabies
Rabies

Rabies is a virus zoonotic neurotropic virus disease that causes acute encephalitis in mammals. It is most commonly caused by a bite from an infected animal, but occasionally by other forms of contact....
 may be classified as an "epidemic," while many cases of a common disease (like the common cold
Common cold

Acute viral rhinopharyngitis, or acute coryza, usually known as the common cold, is a highly contagious, virus infectious disease of the upper respiratory system, primarily caused by picornaviruses or coronaviruses....
) would not.

Endemic diseases


Common diseases that occur at a constant but relatively low rate in the population are said to be "endemic
Endemic (epidemiology)

In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs....
." An example of an endemic disease is malaria
Malaria

Malaria is a Vector -borne infectious disease caused by protozoan parasites. It is widespread in Tropics and subtropical regions, including parts of the Americas, Asia, and Africa....
 in some parts of Africa
Africa

Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km? including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area....
 (for example, Liberia
Liberia

Liberia , officially the Republic of Liberia, is a country on the west coast of Africa, bordered by Sierra Leone, Guinea, C?te d'Ivoire, and the Atlantic Ocean....
) in which a large portion of the population is expected to get malaria at some point in their lifetime.

Non-infectious disease usage


The term "epidemic" is often used in a sense to refer to widespread and growing societal
Society

A society is a group of humans characterized by patterns of relationships between individuals that share a distinctive culture and/or institutions....
 problems, for example, in discussions of obesity
Obesity

Obesity is a condition in which excess body fat has accumulated to an extent that health may be negatively affected. It is commonly defined as a body mass index of 30 kg/m2 or higher....
, mental illness
Mental illness

A mental disorder or mental illness is a psychological or behavioral pattern that occurs in an individual and is thought to cause distress or disability that is not expected as part of normal development or culture....
 or drug addiction
Drug addiction

Drug addiction is widely considered a Pathology. The disorder of addiction involves the progression of acute drug use to the development of drug-seeking behavior, the vulnerability to relapse, and the decreased, slowed ability to respond to naturally rewarding stimuli....
. It can also be used metaphorically to relate a type of problem like those mentioned above.

Notable epidemics through history


Famous examples of epidemics include HIV
AIDS

Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the HIV ....
 (present), the pandemic of the 14th century known as the Black Death
Black Death

The Black Death, was one of the deadliest pandemics in human history, widely thought to have been caused by a bacterium named Yersinia pestis , but recently attributed by some factors to other diseases....
, and the Great Influenza Pandemic which coincided with the end of World War I
World War I

World War I, or the First World War , was a global military conflict which involved the Great powers, organized into two opposing military alliances: the Allies of World War I and the Central Powers....
.

Factors stimulating new epidemics


Factors that have been described by Mark Woolhouse and Sonya Gowtage-Sequeria to stimulate the rise of new epidemics include:

  1. Alterations in agricultural practices and land use
  2. Changes in society and human demographics
    Overpopulation

    Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the world population and its environment , the Earth....
  3. Poor population health (e.g. malnutrition, HIV, ...)
  4. Hospitals and medical procedures
  5. Evolution of the pathogen (e.g. increased virulence
    Virulence

    Virulence refers to the degree of pathogenicity of an organism, or in other words the relative ability of a pathogen to cause disease.The word virulent, which is the adjective for virulence, derives from the Latin word virulentus, which means "full of poison." From an ecology point of view, virulence can be defined as the host's p...
    , drug resistance
    Drug resistance

    Drug resistance is the reduction in effectiveness of a drug in curing a disease or improving a patient's symptoms. When the drug is not intended to kill or inhibit a pathogen, then the term is equivalent to dosage failure or drug tolerance....
    ,)
  6. Contamination
    Contamination

    Contamination is the presence of a minor constituent in another chemical or mixture, often at the trace level. In chemistry, the term usually describes a single chemical, but in specialized fields the term can also mean chemical mixtures, even up to the level of cellular materials....
     of water supplies and food sources
  7. International travel
  8. Failure of public health programs
  9. International trade
  10. Climate change
    Climate change

    Climate change is any long-term significant change in the expected patterns of average weather of a specific region over an appropriately significant period of time....


Several other factors have also been mentioned in different reports, such as the report by professor Andy Dobson and the report by professor Akilesh Mishra .These include :

  1. Reduced levels of biodiversity
    Biodiversity

    Biodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems....
     (e.g. through environmental destruction)
  2. Bad urban planning
    Urban planning

    Urban, city, and town planning is the integration of the disciplines of land use planning and transport planning, to explore a very wide range of aspects of the built and social environments of urbanized municipalities and communities....


Pre-emptive measures


To protect us against the emergence of new epidemics, several preemptive measures have been proposed by the World Health Organisation .

Renewed concern


In August 2007, the World Health Organization
World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health....
 reported an unprecedented rate of propagation of infectious disease
Infectious disease

An infectious disease is a clinically evident disease resulting from the presence of pathogenic microbial agents, including pathogenic viruses, pathogenic bacteria, Mycosis, protozoa, multicellular parasites, and aberrant proteins known as prions....
s.

See also


  • List of epidemics
    List of epidemics

    This article is a list of major epidemics....
  • Population control
    Population control

    Population control is the practice of limiting population increase, usually by reducing the birth rate. The practice has sometimes been voluntary, as a response to poverty, carrying capacity, or out of religious ideology, but in some times and places it has been socially mandated....
  • Overpopulation
    Overpopulation

    Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the world population and its environment , the Earth....
  • Bugchasing and giftgiving
  • Pandemic
    Pandemic

    A pandemic is an epidemic of infectious disease that spreads through populations across a large region; for instance a continent, or even worldwide....
  • Biosecurity
    Biosecurity

    Biosecurity is a set of preventive measures designed to reduce the risk of intentional removal of a valuable biological material. These preventative measures are a combination of systems and practices usually put into place at a legitimate bioscience laboratory that could be sources of pathogens and toxins for malicious use....
  • OpenEpi
    OpenEpi

    OpenEpi is a free, web-based, open source, operating system-independent series of programs for use in epidemiology, biostatistics, public health, and medicine, providing a number of epidemiologic and statistical tools for summary data....
  • Epi Info
    Epi Info

    Epi Info is public domain List of statistical packages for epidemiology developed by Centers for Disease Control and Prevention.Developed by the Centers for Disease Control and Prevention in Atlanta, Georgia , Epi Info has been in existence for over 20 years and is currently available for Microsoft Windows....
  • European Centre for Disease Prevention and Control
    European Centre for Disease Prevention and Control

    Recently established as an independent agency of the European Union , the European Centre for Disease Prevention and Control is taking up growing responsibilities in strengthening Europe?s defences against infectious diseases....
  • Epidemic model


External links

  • - Simulations of epidemic spread across a landscape