CONCEPT OF OUTBREAK, EPIDEMIC & PANDEMIC WITH ITS PHASES
by-DR. RAJESH KUMAR SINGH, (LIVESTOCK & POULTRY CONSULTANT), JAMSHEDPUR, JHARKHAND,INDIA
9431309542, rajeshsinghvet@gmail.com
Three important words: outbreak, epidemic and pandemic are frequently coming in the social media aftermath of the COVID-19 spread. Here in this article I have tried to keep the actual meaning of theses 3 terms from the epidemiology point of views.Simply put, the difference between these three scenarios of disease spread is a matter of scale.
Outbreak———
Small, but unusual.
A disease outbreak happens when a disease occurs in greater numbers than expected in a community or region or during a season. An outbreak may occur in one community or even extend to several countries. It can last from days to years.
Sometimes a single case of a contagious disease is considered an outbreak. This may be true if it is an unknown disease, is new to a community, or has been absent from a population for a long time.
By tracking diseases over time and geography, epidemiologists learn to predict how many cases of an illness should normally happen within a defined period of time, place and population. An outbreak is a noticeable, often small, increase over the expected number of cases.
Imagine an unusual spike in the number of children with diarrhea at a daycare. One or two sick kids might be normal in a typical week, but if 15 children in a daycare come down with diarrhea all at once, that is an outbreak.
When a new disease emerges, outbreaks are more noticeable since the anticipated number of illnesses caused by that disease was zero. As soon as local health authorities detect an outbreak, they start an investigation to determine exactly who is affected and how many have the disease. They use that information to figure out how best to contain the outbreak and prevent additional illness.
Epidemic———
Bigger and spreading.
An epidemic is an outbreak over a larger geographic area. Epidemic is a term that is often broadly used to describe any problem that has grown out of control. An epidemic is defined as “an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population.
An epidemic is an event in which a disease is actively spreading. An epidemic occurs when an infectious disease spreads rapidly to many people. For example, in 2003, the severe acute respiratory syndrome (SARS) epidemic took the lives of nearly 800 people worldwide.
Pandemic———
International and out of control.
the term pandemic relates to geographic spread and is used to describe a disease that affects a whole country or the entire world.
In the most classical sense, once an epidemic spreads to multiple countries or regions of the world, it is considered a pandemic. However, some epidemiologists classify a situation as a pandemic only once the disease is sustained in some of the newly affected regions through local transmission.
To illustrate, a sick traveler with COVID-19 who returns to the India from China doesn’t make a pandemic, but once they infect a few family members or friends, there’s some debate. If new local outbreaks ensue, epidemiologists will agree that efforts to control global spread have failed and refer to the emerging situation as a pandemic.
Phases of a Pandemic—
What are the phases of pandemics and what do they mean?
The World Health Organization (WHO) provides an influenza pandemic alert system, with a scale ranging from Phase 1 (a low risk of a flu pandemic) to Phase 6 (a full-blown pandemic):
- Phase 1: A virus in animals has caused no known infections in humans.
- Phase 2: An animal flu virus has caused infection in humans.
- Phase 3: Sporadic cases or small clusters of disease occur in humans. Human-to-human transmission, if any, is insufficient to cause community-level outbreaks.
- Phase 4: The risk for a pandemic is greatly increased but not certain.
- Phase 5: Spread of disease between humans is occurring in more than one country of one WHO region.
- Phase 6: Community-level outbreaks are in at least one additional country in a different WHO region from phase 5. A global pandemic is under way.
