Outbreak is a term used in
epidemiologyEpidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
to describe an occurrence of
diseaseA disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
greater than would otherwise be expected at a particular time and place. It may affect a small and localized group or impact upon thousands of people across an entire continent. Two linked cases of a rare
infectious diseaseInfectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
may be sufficient to constitute an outbreak. Outbreaks may also refer to
epidemicIn epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
s, which affect a region in a country or a group of countries, or
pandemicA pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...
s, which describe global disease outbreaks.
This animal carries a deadly virus… and the greatest medical crisis in the world is about to happen.
Try to remain calm.
Outbreak is a term used in
epidemiologyEpidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
to describe an occurrence of
diseaseA disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
greater than would otherwise be expected at a particular time and place. It may affect a small and localized group or impact upon thousands of people across an entire continent. Two linked cases of a rare
infectious diseaseInfectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
may be sufficient to constitute an outbreak. Outbreaks may also refer to
epidemicIn epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
s, which affect a region in a country or a group of countries, or
pandemicA pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...
s, which describe global disease outbreaks.
Outbreak investigation
When investigating disease outbreaks, the epidemiology profession has developed a number of widely accepted steps. As described by the
Centers for Disease Control and PreventionThe Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
, these include the following:
- Verify the diagnosis related to the outbreak
- Identify the existence of the outbreak (Is the group of ill persons normal for the time of year, geographic area, etc.?)
- Create a case definition
A case definition from a broader sense encompassing its use in more than just medical terms. A case is a request for a service for a subject - customer, employee, or citizen. The case has supporting information - documents, data, forms, etc. - as part of the request for service...
to define who/what is included as a case
- Map the spread of the outbreak using Information technology
Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...
as diagnosis is reported to insurance
- Develop a hypothesis (What appears to be causing the outbreak?)
- Study hypothesis (collect data and perform analysis)
- Refine hypothesis and carry out further study
- Develop and implement control and prevention systems
- Release findings to greater communities
Types
There are several outbreak patterns, which can be useful in identifying the transmission method or source, and predicting the future rate of infection. Each has a distinctive
epidemic curve, or
histogramIn statistics, a histogram is a graphical representation showing a visual impression of the distribution of data. It is an estimate of the probability distribution of a continuous variable and was first introduced by Karl Pearson...
of case infections and deaths.
- Common source – All victims acquire the infection from the same source (e.g. a contaminated water supply).
- Continuous source – Common source outbreak where the exposure occurs over multiple incubation periods
- Point source – Common source outbreak where the exposure occurs in less than one incubation period
- Propagated – Transmission occurs from person to person.
Outbreaks can also be:
- Behavioral risk related (e.g., sexually transmitted disease
Sexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...
s, increased risk due to malnutritionMalnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
)
- Zoonotic – The infectious agent is endemic to an animal population.
Patterns of occurrence are:
- Endemic
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. For example, chickenpox is endemic in the UK, but malaria is not...
– a communicable disease, such as influenza, measles, mumps, pneumonia, colds, small pox, which is characteristic of a particular place, or among a particular group, or area of interest or activity
- Epidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
– when this disease is found to infect a significantly larger number of people at the same time than is common at that time, and among that population, and may spread through one or several communities.
- Pandemic
A pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...
– occurs when an epidemic spreads worldwide.
Outbreak legislation
Outbreak legislation is still in its infancy and not many countries have had a direct and complete set of the provisions.
However, some countries do manage the outbreaks using relevant acts, such as
public health lawLaw is an important public health tool that plays a critical role in reducing illness and premature death. Public health law examines the authority of the government at various jurisdictional levels to improve the health of the general population within societal limits and norms.Public health law...
.