Disease outbreak

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Difference between outbreak, endemic, epidemic and pandemic Difference between outbreak, endemic, epidemic and pandemic-en.png
Difference between outbreak, endemic, epidemic and pandemic

In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire continent. The number of cases varies according to the disease-causing agent, and the size and type of previous and existing exposure to the agent. Outbreaks include many epidemics, which term is normally only for infectious diseases, as well as diseases with an environmental origin, such as a water or foodborne disease. They may affect a region in a country or a group of countries. Pandemics are near-global disease outbreaks when multiple and various countries around the Earth are soon infected.

Contents

Definition

The terms "outbreak" and "epidemic" have often been used interchangeably. Researchers Manfred S. Green and colleagues propose that the latter term be restricted to larger events, pointing out that Chambers Concise Dictionary and Stedman's Medical Dictionary acknowledge this distinction. [1]

Outbreak investigation

Epidemic curves Epidemic curves.jpg
Epidemic curves

When investigating disease outbreaks, the epidemiology profession has developed a number of widely accepted steps. As described by the United States Centers for Disease Control and Prevention, these include the following: [2]

The order of the above steps and relative amount of effort and resources used in each varies from outbreak to outbreak. [3] For example, prevention and control measures are usually implemented very early in the investigation, often before the causative agent is known. In many situations, promoting good hygiene and hand-washing is one of the first things recommended. Other interventions may be added as the investigation moves forward and more information is obtained. Waiting until the end of an investigation to implement prevention and control measures is a sure way to lose ones job. In outbreaks identified through notifiable disease surveillance, reports are often linked to laboratory results and verifying the diagnosis is straight forward. In outbreaks of unknown etiology, determining and verifying the diagnosis can be a significant part of the investigation with respect to time and resources. Several steps are usually going on at any point in time during the investigation. Steps may be repeated. For example, initial case definitions are often established to be intentionally broad but later refined as more is learned about the outbreak. The above list has 9 steps, others have more. Implementing active surveillance to identify additional cases is often added. [4]

Outbreak debriefing and review has also been recognized as an additional final step and iterative process by the Public Health Agency of Canada. [5]

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 histogram of case infections and deaths. [6]

Outbreaks can also be:

Patterns of occurrence are:

Condition for Declaring an Outbreak Over

By convention, a communicable disease outbreak is declared over when a period of twice the incubation period of the infectious disease has elapsed without identification of any new case, however, for organisms with a short incubation period (e.g. fewer than ten days), a period of three times the incubation period is preferred. [11]

Outbreak legislation

Outbreak legislation is still in its infancy and not many countries have had a direct and complete set of the provisions. [12] [13] However, some countries do manage the outbreaks using relevant acts, such as public health law. [14] World Health Organization member states are obligated by International Health Regulations to report outbreaks. WHO member states are holding a special session in November 2021 to consider the International Treaty for Pandemic Preparedness and Response to establish further legal obligations in managing disease outbreaks. [15]

See also

Related Research Articles

<span class="mw-page-title-main">Quarantine</span> Epidemiological intervention to prevent disease transmission

A quarantine is a restriction on the movement of people, animals, and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been exposed to a communicable disease, yet do not have a confirmed medical diagnosis. It is distinct from medical isolation, in which those confirmed to be infected with a communicable disease are isolated from the healthy population.

<span class="mw-page-title-main">Q fever</span> Coxiella burnetii infection

Q fever or query fever is a disease caused by infection with Coxiella burnetii, a bacterium that affects humans and other animals. This organism is uncommon, but may be found in cattle, sheep, goats, and other domestic mammals, including cats and dogs. The infection results from inhalation of a spore-like small-cell variant, and from contact with the milk, urine, feces, vaginal mucus, or semen of infected animals. Rarely, the disease is tick-borne. The incubation period can range from 9 to 40 days. Humans are vulnerable to Q fever, and infection can result from even a few organisms. The bacterium is an obligate intracellular pathogenic parasite.

<span class="mw-page-title-main">Epidemic</span> Rapid spread of disease affecting a large number of people in a short time

An epidemic is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infections, an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered an epidemic.

<span class="mw-page-title-main">Incubation period</span> Time between infection and the onset of disease symptoms

Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, the incubation period signifies the period taken by the multiplying organism to reach a threshold necessary to produce symptoms in the host.

<span class="mw-page-title-main">Mpox</span> Viral disease of humans and animals

Mpox is an infectious viral disease that can occur in humans and other animals. Symptoms include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes. The illness is usually mild and most of those infected will recover within a few weeks without treatment. The time from exposure to onset of symptoms ranges from five to twenty-one days and symptoms typically last from two to four weeks. Cases may be severe, especially in children, pregnant women or people with suppressed immune systems.

<span class="mw-page-title-main">Contact tracing</span> Finding and identifying people in contact with someone with an infectious disease

In public health, contact tracing is the process of identifying people who may have been exposed to an infected person ("contacts") and subsequent collection of further data to assess transmission. By tracing the contacts of infected individuals, testing them for infection, and isolating or treating the infected, this public health tool aims to reduce infections in the population. In addition to infection control, contact tracing serves as a means to identify high-risk and medically vulnerable populations who might be exposed to infection and facilitate appropriate medical care. In doing so, public health officials utilize contact tracing to conduct disease surveillance and prevent outbreaks. In cases of diseases of uncertain infectious potential, contact tracing is also sometimes performed to learn about disease characteristics, including infectiousness. Contact tracing is not always the most efficient method of addressing infectious disease. In areas of high disease prevalence, screening or focused testing may be more cost-effective.

Infection prevention and control is the discipline concerned with preventing healthcare-associated infections; a practical rather than academic sub-discipline of epidemiology. In Northern Europe, infection prevention and control is expanded from healthcare into a component in public health, known as "infection protection". It is an essential part of the infrastructure of health care. Infection control and hospital epidemiology are akin to public health practice, practiced within the confines of a particular health-care delivery system rather than directed at society as a whole.

<span class="mw-page-title-main">Disease surveillance</span> Monitoring spread of disease to establish patterns of progression

Disease surveillance is an epidemiological practice by which the spread of disease is monitored in order to establish patterns of progression. The main role of disease surveillance is to predict, observe, and minimize the harm caused by outbreak, epidemic, and pandemic situations, as well as increase knowledge about which factors contribute to such circumstances. A key part of modern disease surveillance is the practice of disease case reporting.

Globalization, the flow of information, goods, capital, and people across political and geographic boundaries, allows infectious diseases to rapidly spread around the world, while also allowing the alleviation of factors such as hunger and poverty, which are key determinants of global health. The spread of diseases across wide geographic scales has increased through history. Early diseases that spread from Asia to Europe were bubonic plague, influenza of various types, and similar infectious diseases.

The Centers for Disease Control and Prevention, formed in 1946, is the leading national public health institute of the United States. It is a United States federal agency, under the United States Department of Health and Human Services. Its main goal is to protect public health and safety through the control and prevention of disease, injury, and disability in the US and internationally.

<span class="mw-page-title-main">Field epidemiology</span>

Field Epidemiology is the application of epidemiologic methods to unexpected health problems when a rapid on-site investigation is necessary for timely intervention. A more expansive definition is: The practice of Epidemiology in the field. Work is done in communities often as a public health service and as part of government or a closely allied institution. Field epidemiology is how epidemics and outbreaks are investigated, and is used to implement measures to protect and improve the health of the public. Field epidemiologists must deal with unexpected, sometimes urgent problems that demand immediate solution. Its methods are designed to answer specific epidemiologic questions in order to plan, implement, and/or evaluate public health interventions. These studies consider the needs of those who will use the results. The task of a field epidemiologist is not complete until the results of a study have been clearly communicated in a timely manner to those who need to know, and an intervention made to improve the health of the people.

An epidemic curve, also known as an epi curve or epidemiological curve, is a statistical chart used in epidemiology to visualise the onset of a disease outbreak. It can help with the identification of the mode of transmission of the disease. It can also show the disease's magnitude, whether cases are clustered or if there are individual case outliers, its trend over time, and its incubation period. It can give outbreak investigators an idea as to whether an outbreak is likely to be from a point source, a continuous common source, or a propagated source.

Transmission-based precautions are infection-control precautions in health care, in addition to the so-called "standard precautions". They are the latest routine infection prevention and control practices applied for patients who are known or suspected to be infected or colonized with infectious agents, including certain epidemiologically important pathogens, which require additional control measures to effectively prevent transmission. Universal precautions are also important to address as far as transmission-based precautions. Universal precautions is the practice of treating all bodily fluids as if it is infected with HIV, HBV, or other blood borne pathogens.

<span class="mw-page-title-main">Legionnaires' disease</span> Form of atypical pneumonia

Legionnaires' disease is a form of atypical pneumonia caused by any species of Legionella bacteria, quite often Legionella pneumophila. Signs and symptoms include cough, shortness of breath, high fever, muscle pains, and headaches. Nausea, vomiting, and diarrhea may also occur. This often begins 2–10 days after exposure.

<span class="mw-page-title-main">Outbreak response</span> Measures to reduce the spread of an infectious disease

Outbreak response or outbreak control measures are acts which attempt to minimize the spread of or effects of a disease outbreak. Outbreak response includes aspects of general disease control such as maintaining adequate hygiene, but may also include responses that extend beyond traditional healthcare settings and are unique to an outbreak, such as physical distancing, contact tracing, mapping of disease clusters, or quarantine. Some measures such as isolation are also useful in preventing an outbreak from occurring in the first place.

In epidemiology, a non-pharmaceutical intervention (NPI) is any method used to reduce the spread of an epidemic disease without requiring pharmaceutical drug treatments. Examples of non-pharmaceutical interventions that reduce the spread of infectious diseases include wearing a face mask and staying away from sick people.

<span class="mw-page-title-main">Latent period (epidemiology)</span> Time interval between infection by a pathogen and the individual becoming infectious

In epidemiology, particularly in the discussion of infectious disease dynamics (modeling), the latent period is the time interval between when an individual or host is infected by a pathogen and when that individual becomes infectious, i.e. capable of transmitting pathogens to other susceptible individuals.

<span class="mw-page-title-main">Infectious period</span>

In epidemiology, particularly in the discussion of infectious disease dynamics, the infectious period is the time interval during which a host is infectious, i.e. capable of directly or indirectly transmitting pathogenic infectious agents or pathogens to another susceptible host. The infectious period can start before, during or after the onset of symptoms, and it may stop before or after the symptoms stop showing. It is also known in the literature by a variety of synonymous terms such as the infective period, the period of infectiousness, communicability period, the period of communicability, contagious period, the period of contagiousness, transmission period or transmissibility period. The degree of infectiousness is not constant but varies through the infectious period.

In infectious disease epidemiology, a sporadic disease is an infectious disease which occurs only infrequently, haphazardly, irregularly, or occasionally, from time to time in a few isolated places, with no discernible temporal or spatial pattern, as opposed to a recognizable epidemic outbreak or endemic pattern. The cases are so few and separated so widely in time and place that there exists little or no discernable connection within them. They also do not show a recognizable common source of infection.

The following outline is provided as an overview of and topical guide to concepts related to infectious diseases in humans.

References

  1. ↑ Green MS, Swartz T, Mayshar E, Lev B, Leventhal A, Slater PE, Shemer J (2002). "When is an epidemic an epidemic?" (PDF). Israel Medical Association Journal. 4 (1): 3–6. PMID   11802306.
  2. ↑ Steps of an Outbreak Investigation, EXCITE | Epidemiology in the Classroom | Outbreak Steps
  3. ↑ Perrocheau A, Jephcott F, Asgari-Jirhanden N, Greig J, Peyraud N, Tempowski J (2023). "Investigating outbreaks of initially unknown aetiology in complex settings: findings and recommendations from 10 case studies". International Health. 5 (15): 537–546. doi:10.1093/inthealth/ihac088. PMC   10472873 . PMID   36630891.
  4. ↑ "Principles of Epidemiology in Public Health Practice" (PDF). Centers for Disease Control and Prevention. CDC. Retrieved 6 August 2016.
  5. ↑ Public Health Agency of Canada. "Canada's Food-borne Illness Outbreak Response Protocol (FIORP) 2010: To guide a multi-jurisdictional response" . Retrieved 22 March 2013.
  6. ↑ "SARS Outbreak Study 2". epiville.ccnmtl.columbia.edu. Center for New Media Teaching and Learning at Columbia University. Archived from the original on March 19, 2009.
  7. ↑ Glossary of Epidemiology Terms, Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  8. ↑ Glossary of Epidemiology Terms. Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  9. ↑ Glossary of Epidemiology Terms. Cdc.gov (2007-04-25). Retrieved on 2010-11-25.
  10. ↑ "Health Topic: Behavioral Risk Factors". Center for Disease Control. Archived from the original on September 28, 2008. Retrieved 30 March 2020.
  11. ↑ Ghebrehewet S, Stewart AG, Baxter D, Shears P, Conrad D, Kliner M, eds. (October 2016). Health Protection. Vol. 1. Oxford University Press. p. 210. doi:10.1093/med/9780198745471.001.0001. ISBN   978-0-19-874547-1.
  12. ↑ "Bioterrorism Training and Curriculum Development Program". Archived from the original on 3 March 2016. Retrieved 2 August 2008.
  13. ↑ Star Publications. "Outbreak actions protected by law" . Retrieved 2 August 2008.
  14. ↑ The State of Queensland Government. "Legislation and Powers of Entry" . Retrieved 2 August 2008.
  15. ↑ "WHA to hold pandemic treaty talks in November". 25 May 2021.
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